From Virus to Vaccination: Bridging Gaps Materials

FROM VIRUS TO VACCINATION: BRIDGING GAPS IN INFLUENZA PREVENTION AND PRACTICE

Faculty:

Steven Malen, PharmD, MBA

Steven Malen graduated with a dual degree in Doctor of Pharmacy (PharmD) and Master of Business Administration (MBA) from the University of Rhode Island. Steven Malen has worked as a clinical pharmacist in the retail, specialty, and compounding sectors.

Pamela Sardo, PharmD, BS

Pamela Sardo, PharmD, BS, is a freelance medical writer and licensed pharmacist. She is the founder and principal at Sardo Solutions in Texas. Pam received her BS from the University of Connecticut and her PharmD from the University of Rhode Island. Pam’s career spans many years in retail, clinics, hospitals, long-term care, Veterans Affairs, and managed health care responsibilities across a broad range of therapeutic classes and disease states.

Abstract

Influenza vaccines can be effective in preventing influenza illness. Vaccine efficacy varies based on the influenza variant, the severity of a particular flu season, and differences in the flu vaccines prepared for that season. The Centers for Disease Control and Prevention recommends that everyone six months of age and older receive an annual influenza vaccination. The best way to protect against influenza includes recognizing symptoms, preventing the spread, and receiving annual vaccination. This activity discusses the epidemiology, symptoms, and potential complications of influenza, as well as trivalent vaccine formulations. Trivalent vaccine formulations are available in injectable and nasal spray forms. Antiviral medications, which are available for treating influenza in patients at higher risk of serious complications, will also be covered.

Accreditation Statements

In support of improving patient care, RxCe.com LLC is jointly accredited by the Accreditation Council^TM for Continuing Medical Education (ACCME^®), the Accreditation Council for Pharmacy Education (ACPE^®), and the American Nurses Credentialing Center (ANCC^®), to provide continuing education for the healthcare team.

Joint Universal Activity Number: The Joint Accreditation Universal Activity Numbers assigned to this activity are as follows:

Pharmacy Technicians: JA4008424-0000-26-081-H06-T

Credits: 2 contact hour(s) (0.2 CEU(s)) of continuing education credit.

Credit Types:

Pharmacy - 2 Credits

Type of Activity: Knowledge

Media: Computer-Based Training (i.e., online courses)

Estimated time to complete activity: 2 contact hour(s) (0.2 CEU(s)), including Activity Pre-Test, Post-Test, and Activity Evaluation.

Release Date: June 1, 2026 Expiration Date: September 26, 2028

Target Audience: This educational activity is for Pharmacy Technicians.

How to Earn Credit: From June 1, 2026, through September 26, 2028, participants must:

Read the “learning objectives” and “author and planning team disclosures;”

Take the “Educational Activity Pre-Test;”

Study the section entitled “Educational Activity;” and

Complete the Educational Activity Post-Test and Activity Evaluation. The Educational Activity Post-Test will be graded automatically. Following successful completion of the Educational Activity Post-Test with a score of 70% or higher, a statement of participation will be made available immediately. (No partial credit will be given.)

CE and CME Credits: Credits for this course will be uploaded to CPE Monitor® for pharmacists and pharmacy technicians. Physicians may receive AMA PRA Category 1 Credits™ and apply them toward Maintenance of Certification (MOC) requirements. Physician Assistants may earn AAPA Category 1 CME credits, reportable through PA Portfolio. All learners must verify their individual licensing board’s specific requirements and eligibility criteria.

Statement of Need

Major public health organizations, including the Centers for Disease Control and Prevention and the American Academy of Pediatrics, recommend routine annual influenza vaccination for everyone aged 6 months and older. Pharmacy technicians play a vital, expanding role in influenza vaccination, including managing vaccine inventory and preparing doses. In some states, properly trained or certified pharmacy technicians can administer immunizations under direct pharmacist supervision. Training in vaccine administration and in understanding their potential side effects is needed for pharmacy technicians to fulfill their role in an annual influenza vaccination program.

Learning Objectives: Upon completion of this educational activity, participants should be able to:

Identify the types of influenza virus

Discuss prevention strategies to reduce the spread of influenza infection

Identify approaches to influenza vaccine adverse reactions

Describe influenza treatment options

Disclosures

The following individuals were involved in planning, developing, and/or authoring this activity: L. Austin Fredrickson, MD, FACP; Kristina (Tia) Neu, RN; and Pamela Sardo, PharmD, BS. None of the individuals involved in developing this activity has a conflict of interest or financial relationships related to the subject matter. There are no financial relationships or commercial or financial support relevant to this activity to report or disclose by RxCe.com or any of the individuals involved in the development of this activity.

© RxCe.com LLC 2026: All rights reserved. No reproduction of all or part of any content herein is allowed without the prior, written permission of RxCe.com LLC.

Educational Activity

From Virus to Vaccination: Bridging Gaps in Influenza Prevention and Practice

Introduction

Influenza is a highly contagious viral illness of the respiratory tract that typically occurs in late fall, winter, and early spring. It affects millions of people in the United States and millions more worldwide every year. Influenza vaccines can be effective at preventing influenza, decreasing the severity of illness, and may reduce the need for hospitalization. Vaccine efficacy varies based on the influenza variant, the severity of a particular flu season, and differences in the vaccines prepared for that season. Trivalent vaccine formulations are available, including both injectable and nasal spray forms.

Influenza Virus

Influenza is a common and highly infectious RNA virus that causes respiratory illness. There are four types of the virus: types A, B, C, and D.¹ Types A and B are the more common causes of the yearly, seasonal epidemics that are informally referred to as the flu season. Influenza A is the type most responsible for causing pandemics because of its high susceptibility to antigenic variation.² Type C is not thought to cause human epidemics and can cause very mild respiratory illness or possibly no symptoms at all.^1,2 Type D is found in animals, such as cattle.¹

The influenza virus is transmitted in two ways: 1) infected droplets that become airborne when someone coughs, sneezes, spits, or talks may enter the respiratory tract through the mucosal surfaces of the trachea and the bronchi; and, 2) direct contact with infected objects, i.e., touching a telephone handset or shaking hands with someone whose hands are contaminated with the virus.³ A person with influenza may be contagious for days and may be able to pass the virus to someone else before they know they are sick.^4-6 The first 3 to 4 days after the illness begins are the most contagious. From 1 day before symptoms develop to 5-7 days after feeling sick, most healthy individuals may be able to infect others. Children and individuals with weakened immune systems may be contagious for a longer period.⁵

Infected Droplets

The influenza virus spreads quite easily via respiratory droplets, but certain circumstances limit this mode of transmission. The infected droplets usually do not travel very far (usually < 6 feet).^3,7 They do not remain in the air for a long time, and environmental conditions affect how long they are viable. For example, if the air humidity is low and the air temperature is cold, the survival time of infected airborne droplets will increase.⁸ If someone has influenza, all respiratory secretions and bodily fluids are potentially contaminated.⁹

Contact Transmission

Contact transmission occurs when an uninfected person comes into contact with a surface that is contaminated with the influenza virus.^9,10 Once the virus is on the skin of an uninfected person, it can then enter the body by contact with the mucosal surfaces of the conjunctiva, the mouth, or the nose. In all healthcare settings, including inpatient and outpatient pharmacies, it is important to clean surfaces regularly to prevent the spread of communicable diseases (including influenza). Surfaces, such as credit card readers and signature pads, as well as any other frequently touched surfaces, should be cleaned regularly.

According to a 2017 study, a viable influenza virus has been found to persist on environmental surfaces for up to two weeks.¹⁰ Surface contamination with the influenza virus during the influenza season appears to be a common occurrence. Large respiratory droplets can contaminate fomites (i.e., objects that can carry infections, such as doorknobs, keyboards, and phones).⁸ This may play a significant role in transmission.⁸

Epidemiology of Influenza

Influenza is highly contagious and a common cause of epidemics.⁶ Each year, 10%-20% of the world’s population develops an influenza infection, and every year in the United States, millions of people get the flu. There are thousands of deaths from influenza, and hundreds of thousands of people are hospitalized due to complications of influenza infection.⁶ The most recent preliminary estimates from the U.S. Centers for Disease Control and Prevention (CDC) for the 2023-2024 flu season estimate that 40 million individuals experienced flu illnesses, approximately 18 million required medical visits related to the flu, and 470,000 individuals were hospitalized due to influenza.¹¹ This reflects a moderate season, with vaccination preventing an estimated 9.8 million additional illnesses.¹¹ Influenza epidemics are noteworthy for several reasons: they occur every year, but the severity and outcomes of these outbreaks can differ.¹²

Annual Epidemics

For most people, flu season has become a predictable and unremarkable event each winter. The human immune system develops antibodies after viral exposure, and vaccines are widely used to combat the flu.¹²

With the availability of antibodies and vaccines, one might wonder why influenza epidemics occur annually. The answer is that the influenza virus adapts.^6,13,14 Influenza viruses can periodically change their hemagglutinin (H) and neuraminidase (N) glycoproteins on the surface of the virus, which the pathogen needs to initiate and spread infection and enter cells. These glycoproteins also act as antigens and form the basis of variant names (e.g., H1N1, H3N2).

Major changes are referred to as antigenic shifts.¹³ Minor changes are referred to as antigenic drifts.¹³ Antigenic drifts occur almost annually, while antigenic shifts may be spaced out by years or decades.¹³ Moreover, antigenic shifts are more likely to be the cause of pandemics or epidemics, whereas antigenic drifts are usually associated with regional epidemics.¹³ Prior exposure to influenza and vaccination can provide immunity to influenza, but because of antigenic drift, which occurs almost annually, this protection may only last for several years.^13,14 Additionally, these seasonal changes make it challenging to determine the timing and formulation of the annual flu vaccine. The timing of vaccinations, particularly vaccine efficacy, is crucial, as even with an effective flu vaccine formulation, the vaccine is more effective when administered in the months preceding the peak of an influenza epidemic.¹⁵

Seasonal Variations

Influenza and influenza infections are endemic. The virus is always present, and people can contract influenza infections throughout the year. The flu season varies from year to year and across geographical regions and climates. In the U.S., influenza activity often begins to increase in October. “Most of the time, flu activity peaks between December and February, although significant activity can last as late as May.”¹² In areas with a temperate climate (like the U.S.), variation in influenza activity may be due to low humidity/dry air, more time spent indoors (thus closer and more frequent interpersonal contacts), a seasonal decrease in immune system functioning, and decreased mucociliary clearance of the virus, which can be exacerbated by the dry air in an area with low humidity.^16-17

Clinical Features and Diagnosis

Influenza is contagious 1-2 days before an infected person becomes symptomatic and is contagious for approximately 5-7 days after symptoms begin.⁵ Viral shedding of influenza may begin 24 hours before the infected person becomes symptomatic, and the greater the degree of shedding, the more contagious the source will be.¹⁸ Studies show that the average duration of shedding is reported to be 4.8 days, with shedding most often ending by day 7.¹⁸ However, it is not uncommon for shedding to occur after day 7 up to day 10, especially in children, adults with comorbid and/or chronic medical conditions, immunocompromised individuals, and hospitalized patients.^18,19 Children <5 years tend to shed more virus for longer periods than older age groups.¹⁹

In adults, influenza infection is typically characterized by fatigue, fever, headache, malaise, and muscle aches (myalgia).^20,21 The fever is typically 100-104°F, but it can be higher. It is important to note that not everyone with the flu will have a fever.^21,22 Respiratory signs and symptoms include a nonproductive cough, nasal congestion, runny nose, and sore throat.^20,21 The onset is generally abrupt. The worst effects usually last several days, but many people are fatigued and weak for weeks after an influenza infection has effectively ended. Influenza infection in a child is similar, but the fever may be higher, and respiratory signs can be less pronounced. A child with influenza is more likely to have gastrointestinal (GI) problems, such as anorexia, diarrhea, and vomiting, than adults.^19-21

In most cases, influenza is diagnosed using clinical criteria. In 2018, the Infectious Diseases Society of America updated its guidelines on the diagnosis and treatment of seasonal influenza.²³ A patient is diagnosed with influenza if they exhibit typical flu signs and symptoms and the illness occurs during flu season.^22,23 “Cough and fever provide the most predictive signs and symptoms when influenza viruses are circulating in the community.”²³ Laboratory confirmation of the presence of the virus is not necessary or recommended unless certain criteria are present. In outpatient cases, laboratory confirmation is crucial for patients who are immunocompromised or at high risk of influenza-related complications. This would include immunocompromised patients with flu-like symptoms during the non-flu season, pneumonia, or a nonspecific respiratory illness (e.g., cough without fever).²³

In patients who need hospitalization, laboratory confirmation should be used in the following patients: patients with pneumonia or other acute respiratory illness, regardless of the presence or absence of fever; patients with an acute and deteriorating cardiopulmonary disease (e.g., asthma or congestive heart failure) to help prevent these conditions from being worsened by the flu; and patients at risk for developing respiratory distress syndrome.^22,23 Laboratory confirmation helps clinicians make treatment and management decisions, such as prescribing antivirals.²³

Influenza tests can be performed on essentially any respiratory tract secretion. The rapid diagnostic test will usually be performed on a nasopharyngeal swab, and the results are typically ready (depending on the specific test) in 15 minutes.²⁴

Severity, Outcomes, and High-Risk Groups

Influenza outbreaks vary in severity. This is likely due to the number of susceptible individuals, the vaccination rate, and the intrinsic virulence of a particular strain of the virus. Clinicians should monitor local surveillance data to determine the types and subtypes of influenza viruses circulating in communities.²⁵

Influenza can affect virtually every organ system of the body. The CDC has reported that influenza complications “can vary by age, immune status, and underlying medical conditions.”²⁴ Examples of complications include “worsening of underlying chronic medical conditions (e.g., worsening of congestive cardiac failure; asthma exacerbation; exacerbation of chronic obstructive pulmonary disease); lower respiratory tract disease (e.g., pneumonia, bronchiolitis, croup, respiratory failure); invasive bacterial co-infection; cardiac (e.g., myocarditis); musculoskeletal (e.g., myositis, rhabdomyolysis); neurologic (e.g., encephalopathy, encephalitis); multi-organ failure (e.g., septic shock, renal failure, respiratory failure).”²⁴

Bacterial or viral pneumonia is the most common complication of influenza.²⁶ The combination of influenza and pneumonia is a leading cause of mortality in the United States.²⁷ Asthma has been reported to be the most common pre-existing condition among patients hospitalized for influenza; however, the relationship between influenza and asthma remains unclear.^28,29

Children

Children are often affected first and are at greater risk of severe influenza or complications by virtue of their age.²⁵ The flu is more dangerous than the common cold for children.²⁵ Children younger than 5 years of age, especially those younger than 2 years old, are at higher risk of serious flu-related complications than older children. Children with underlying medical conditions are also at greater risk.²⁵ Within the pediatric population, certain groups, such as American Indian and Alaskan Native children, also present with greater risks. American Indian and Alaskan Native children are more likely to have severe flu illness that results in hospitalization or death.³⁰

Advisory Committee on Immunization Practices and Pregnancy

Pregnant women have a higher risk of serious influenza complications than women who are not pregnant.³¹ This risk is present up to 2 weeks postpartum.^32,33 The signs and symptoms of an influenza infection are the same as for other populations, and the testing and treatment are the same as well.

The Advisory Committee on Immunization Practices (ACIP) recommends that all women who are or may become pregnant during the influenza season receive an influenza vaccination.³² Inactivated influenza vaccines are recommended in each pregnancy and may be given in any trimester.³³ Vaccination of the pregnant mother has been associated with a reduced risk of influenza illness in their infants during the first months after birth, when they are too young to receive the influenza vaccine.³² The live, attenuated vaccine should be avoided in pregnant women.³²

Pregnant women and women who are two weeks postpartum or those who have lost a pregnancy in the preceding two weeks and who have or are suspected of having an influenza infection should be promptly treated with an antiviral medication.³³ These same groups should be given prophylactic antivirals if, in the opinion of a clinician, they have had significant exposure to influenza.³³ Oseltamivir and zanamivir are generally considered safe for pregnant women and fetuses.³³

Older Adults and People with Comorbidities

Older adults and people who have certain medical conditions are at a higher risk for complications, hospitalization, and death.¹¹ The death rate from influenza has been estimated to be 6.3–52 per 100,000 annually across seasons, with the 2023-2024 season resulting in approximately 21,000–44,000 deaths.¹¹ Outbreaks typically last for two to three months. Older adults and people who have certain medical conditions are at a higher risk for complications, hospitalization, and death, particularly due to antigenic shifts in A(H3N2) and B/Victoria lineages.¹¹

Preventing the Spread of Influenza Infection

Preventing the spread of influenza involves vaccination and the isolation of infected patients. Additionally, when treating flu patients, healthcare professionals must adhere to proper infection control techniques and precautions.^9,34-36

Infection Control Techniques and Precautions

When caring for a patient with influenza, healthcare clinicians must always follow Standard Precautions, Droplet Precautions, and Respiratory Hygiene and Cough Etiquette.^34-36 Patient areas should consistently be cleaned to help prevent the spread of influenza.

Standard Precautions

Standard Precautions include hand hygiene, appropriate use of personal protective equipment (PPE), Respiratory Hygiene and Cough Etiquette, safe injection practices, and safe handling of potentially contaminated equipment or surfaces in the patient environment.^34-36

Droplet Precautions

If a patient has confirmed or suspected influenza, healthcare providers should follow droplet precautions for 7 days after the onset of the illness or until 24 hours after the fever and respiratory symptoms have resolved, whichever is longer. Droplet precautions include the following:^34-36

The patient should be in a single room.

Clinicians may choose to wear a mask when providing patient care or when within 3 feet of an infected individual.³⁷ Additionally, clinicians should perform hand hygiene before entering the room and after removing their mask.

Clinicians should wear appropriate PPE when contact with secretions is expected or possible, including eye protection (goggles or a face shield) and a gown.

Respiratory Hygiene/Cough Etiquette

Covering the mouth and nose with a tissue should be done when someone is coughing or sneezing.^33-35 The used tissue should be placed in the nearest waste receptacle. Hand hygiene should be performed using soap and water or an alcohol-based hand sanitizer after contact with respiratory secretions or contaminated objects.^33-35

Infected Individuals Should Avoid Contact with Others

The recommendation that infected persons isolate or stay home is a prevention strategy to reduce transmission of influenza from symptomatic individuals. The CDC recommends that symptomatic individuals stay home and avoid contact with others until 24 hours after their fever resolves and symptoms improve, or for 5 days after symptom onset if they do not have a fever.¹⁹

Influenza Vaccines for the Prevention of Influenza Infection

A 2024 study in California estimated an overall vaccine effectiveness of 41% against lab-confirmed flu during the 2023-24 season, with 26% in older adults and 68% against hospitalization (CIDRAP, 2024), highlighting the need for annual updates due to antigenic drift.³⁸ Conversely, a 2024 case study from a European network (PMC, 2024) examined influenza A outbreaks in primary care, finding 32–53% vaccine effectiveness in preventing medically attended illness, with higher rates (59%) in older adults using adjuvanted vaccines.³⁹

CDC Annual Vaccination Recommendation

The CDC recommends annual influenza vaccination for everyone 6 months of age and older. It is also crucial for healthcare workers to be vaccinated, as they work closely with vulnerable populations.⁴⁰

Available vaccines are evaluated for each flu season. Vaccine formulations and types may vary by subtype or lineage, as well as by the vaccine's efficacy against a specific strain. Timing of vaccinations is also important (i.e., vaccination early in the flu season versus late in the season).⁴¹

Vaccines Available for the 2025-2026 Flu Season: Trivalent Preparations

Trivalent vaccines contain three components, as the name suggests.^42,43 The trivalent preparations protect against two types of influenza A viruses and one type of influenza B virus. In the past flu seasons, quadrivalent preparations were used to protect against two types of influenza A viruses and two types of influenza B viruses; however, the B/Yamagata lineage virus has not circulated globally since early 2020.^42,43 Therefore, for the 2025-2026 flu season, only trivalent flu vaccines will be used in the U.S. These vaccines protect against an A(H1N1) virus, an A(H3N2) virus, and a B/Victoria lineage virus.⁴²

Trivalent vaccine formulations for the 2025-2026 flu season include injectable vaccines (e.g., Flublok^®)^32,44 and nasal spray flu vaccines (e.g., FluMist^®).^45,46 The recombinant influenza vaccine Flublok, previously approved for individuals 18 years and older, is now approved for individuals aged 9 and older.^32,44 FluMist, a nasal spray flu vaccine, is now approved for self-administration by adults under 50 and children aged two and older. It can be ordered online and delivered to homes.⁴⁶

Thimerosal-Free Formulations

For the 2025-2026 flu season, the CDC recommends that children aged 18 and younger, pregnant women, and all adults receive flu vaccines in single-dose, thimerosal-free formulations.⁴⁷ Flublok and FluMist are thimerosal-free.

People Who Should Not Get a Flu Vaccine

People who should not be vaccinated for influenza are as follows:^32,48,49

Children < 6 months old

Anyone who has had a severe reaction to influenza vaccinations

Precaution for anyone who develops Guillain-Barré syndrome (GBS) within six weeks after any influenza vaccine.

Egg allergies: Most flu vaccines contain a small amount of egg proteins because they are manufactured using egg-based technology. Studies have shown that reactions to these proteins in vaccines are unlikely to cause severe allergic reactions.⁴⁸ Based on these studies, the professional medical organizations have made the following recommendations:

As of the 2022-23 influenza season, the ACIP has recommended annual influenza vaccination for all persons aged 6 months and older with any licensed influenza vaccine appropriate for the recipient's age and health status, even if they have an egg allergy.⁴⁸ A severe previous allergic reaction from an egg allergy does not change the recommendation.⁴⁹ However, such individuals should be vaccinated in a medical setting, supervised by a provider who can recognize and manage a severe allergic reaction.⁴⁸

The American Academy of Pediatrics recommends that all children with an egg allergy of any severity receive an influenza vaccine without any additional precautions beyond those recommended for any vaccine.⁵⁰

The Joint Task Force of the American Academy of Allergy, Asthma and Immunology (AAAAI) and the American College of Allergy, Asthma and Immunology (ACAAI) concur with the CDC’s and AAP’s recommendations.⁵¹

When Should a Person Get Vaccinated?

The best time for a person to get vaccinated is before the flu season begins in their community. Generally, September and October each year are good times to get vaccinated against the flu.³² Vaccination after this time is still recommended, as flu activity can continue into May. The CDC currently recommends that adults 65 and older not receive the vaccine early (in July or August), as protection may decrease over time. Children can get vaccinated as soon as the vaccine becomes available, even if that means they are vaccinated in July or August. Early vaccination can also be considered in the third trimester of pregnancy, as it may help protect the infant during the first months of life before they are eligible to receive an influenza vaccine.^32,52

Routes of Administration

Depending on the formulation, influenza vaccines can be given intradermally, intramuscularly, or nasally. The choice of vaccine preparation depends on the year, the patient’s age and comorbidities, and the risk of adverse reactions.⁵³ Intramuscular injections of inactivated influenza vaccines should be administered with a needle long enough to reach deep into the muscle. A 5/8-inch needle is suitable for children and thin adults, while a 1-inch needle is standard for most adults when administering injections into the deltoid. When administering into the thigh, the appropriate needle sizes are as follows: 6 to 11 months, 1 inch; 1 to 10 years, 1 to 1¼ inches; and for children and adults 11 years and older, 1 to 1½ inches.⁵⁴ A 22–25-gauge needle should be used. The needle should be inserted into the muscle at a 90-degree angle to the skin, or subcutaneously at a 45-degree angle, with a quick, thrusting motion.⁵⁴ The entire contents of the syringe should be injected. All used needles and syringes should be disposed of in a sharps container. Appropriate injection sites include the deltoid muscle of the arm or the anterolateral thigh muscle.⁵³

Intranasal administration of live attenuated influenza vaccine should be performed with the patient upright.⁵⁵ The rubber tip protector should be removed, and the tip should be placed just inside the nostril to ensure the vaccine is delivered into the nose.⁵⁵ During vaccine administration, the patient should breathe normally. With a single motion, the administrator should depress the plunger as rapidly as possible until the dose-divider clip prevents further advancement. After administration in the first nostril, the dose-divider clip should be removed by pinching it away from the plunger.⁵⁵ Then, the tip of the applicator should be inserted into the other nostril, using the same technique, and the second half of the vaccine should be administered.⁵⁵ The applicator should be disposed of in the sharps container after use.^45,46,55

Pharmacy Staff and Vaccination Rates

Pharmacists and pharmacy technicians can play a significant role in influenza vaccination rates.⁵⁶ A large portion of retail pharmacies offer flu vaccines, and many insurance companies cover them at no copay.⁴² During peak vaccination periods, it is crucial to maintain a properly staffed pharmacy to administer vaccines and maintain normal workflow. It may also be helpful to have a chart or list of NDC numbers, indicating which vaccinations are in stock and which age groups they are suitable for. This will help ease order entry. Some pharmacists are also involved in alternative vaccination clinics, such as long-term care facilities, schools, and disaster relief areas. Staying up to date on current recommendations is necessary as questions about COVID, pneumococcal, and other vaccines may be addressed at the time of influenza vaccine administration.

Treating Influenza Infection

A patient diagnosed with the flu receives standard supportive care. Patients with influenza complications receive ongoing monitoring and care.

Treatment with Antiviral Medications

Treatment with antiviral medication can shorten the duration of influenza symptoms by approximately one to two days.⁵⁷ Additionally, antivirals may reduce the risk of complications and lower viral shedding and titers. Antiviral drugs are particularly beneficial for individuals in high-risk groups, and their efficacy is less affected by antigenic drift compared to vaccines.⁵⁸

The antivirals used to treat and prevent influenza are neuraminidase inhibitors.⁵⁹ These drugs work by hindering the activity of the enzyme neuraminidase and preventing virions from being spread to uninfected cells. The neuraminidase inhibitors approved by the Food and Drug Administration (FDA) for treating influenza are oseltamivir (oral), peramivir (infusion), and zanamivir (nasal inhaler).⁵⁸ All three antivirals are effective against influenza A and B.⁶⁰ Oseltamivir and zanamivir are the most commonly used antivirals. Peramivir is given to patients who cannot tolerate oral medications and/or cannot use an inhaled medication.⁵⁸

Baloxavir marboxil (Xofluza^®) is an influenza virus polymerase acidic (PA) endonuclease inhibitor indicated for the treatment of acute uncomplicated influenza in patients 5 years of age and older who have been symptomatic for no more than 48 hours and who are otherwise healthy or at high risk of developing influenza-related complications.⁶¹ It is also approved for post-exposure prophylaxis of influenza in patients 5 years of age and older who have been exposed to an individual with influenza.⁶¹

Antiviral treatment is not recommended for people who are < 65 years of age, do not have risk factors, and have a mild case of the flu; however, a clinician may decide that a patient in one of these categories may be helped by an antiviral and decide to initiate treatment.⁵⁸

Antiviral therapy should be initiated as soon as possible, preferably within 48 hours of the onset of influenza symptoms. The earlier treatment is initiated, the more likely it is to be successful; antiviral treatment should not be withheld while awaiting laboratory confirmation of influenza infection.^58,62 In patients hospitalized or with a severe case of flu, initiating antiviral treatment after 48 hours may provide some benefit.⁵⁸

The duration of antiviral therapy for treating influenza is 5 days for oseltamivir and zanamivir, and a single dose for peramivir and baloxavir marboxil. Treatment dosing typically varies, and this should always be confirmed with the patient or their provider before dispensing the treatment to ensure the appropriate instructions are followed.

Antiviral Medication Adverse Effects

The adverse effects of neuraminidase inhibitors are generally mild and seldom severe. Nausea, vomiting, headache, and pain are common adverse effects of oseltamivir.⁶³ Diarrhea is a common adverse effect of peramivir. Zanamivir (aerosol inhaler) is not recommended for patients who have pre-existing airway disease, such as asthma and/or chronic obstructive pulmonary disease (COPD), as there have been reports of bronchospasm when the drug is given to this patient population.⁶³ The most common adverse reactions in patients taking baloxavir marboxil include diarrhea, bronchitis, nausea, sinusitis, and headache.⁶¹

The CDC does not endorse widespread prophylactic use of antiviral medication; however, antiviral medication should be considered for high-risk individuals who have been exposed to influenza, people who are immunocompromised and might not respond to vaccination, people for whom the influenza vaccination is contraindicated, and those who have been exposure to influenza, and when treating residents of institutions (i.e., long-term care facilities) during an outbreak.⁶⁴

Role of Pharmacists, Pharmacy Technicians, and Interns

The CDC provides pharmacists, pharmacy technicians, and other health clinicians with ongoing information and updates on influenza outbreaks, treatments, and recommendations for seasonal influenza immunization and prevention. Pharmacists and technicians should stay informed about current guidelines to effectively answer patients' questions about vaccination and ensure that vaccinations are appropriate for everyone.

Federal law allows state-qualified pharmacists to administer vaccines;⁶⁵ however, several states have restrictions on which vaccines pharmacists can administer and/or on the age limits for individuals a pharmacist can vaccinate. Some states also differ on the pharmacist’s authority to prescribe and/or administer a vaccine without a patient-specific prescription from another healthcare clinician. Pharmacists and technicians should familiarize themselves with their state's vaccination regulations. If a state does not have specific training requirements for pharmacists to order and administer vaccines, they must complete a vaccination training program of at least 20 hours, approved by the ACPE, to do so. This training must include hands-on injection techniques, clinical evaluation of vaccine indications and contraindications, and recognition and treatment of emergency vaccine reactions.⁶⁵

Qualified technicians and pharmacy interns may also administer seasonal influenza vaccinations to adults aged 19 or older via ACIP’s standard immunization schedule under the Public Readiness and Emergency Preparedness Act (PREP Act). Technicians and interns administering vaccinations must be supervised by a readily available licensed pharmacist qualified to administer vaccinations. All individuals administering vaccinations must hold a current certificate in Basic Cardiopulmonary Resuscitation (BLS).⁶⁵

Pharmacists must also comply with record-keeping and reporting requirements in the jurisdiction where they administer vaccines, which may include informing the patient’s primary care provider when available, submitting information to the state or local vaccine registry, reporting adverse events, and, if available, reviewing the vaccine registry to ensure appropriate administration. These tasks may be done with the assistance of a pharmacy technician.

Travelers and Influenza Vaccination

Influenza variants occur in different geographic areas.³⁷ People who travel may become exposed to influenza while visiting regions where the virus is actively circulating or when traveling in large groups, such as on a plane or cruise ship. Influenza vaccination before travel may reduce the risk of influenza; vaccination is recommended at least 2 weeks before travel. Unvaccinated residents of the U.S., are at higher risk for influenza complications during the previous Northern Hemisphere fall or winter and should consider influenza vaccine administration before traveling to the tropics, the Southern Hemisphere, or on cruise ships or with large groups traveling to any location.³⁷ Healthcare providers and pharmacists may discuss influenza risk with a person before they travel.

Special Considerations of Influenza Vaccination

Federal law requires health care providers who administer vaccines to maintain the patient’s permanent medical records of any vaccine injury listed in the Vaccine Injury Table and to make the record available to the patient’s legal representative.^66,67 Individuals with vaccine injuries described in the Vaccine Injury Table are eligible to receive compensation under the National Vaccine Injury Compensation Program (VICP). In case of death, the appropriate person may receive compensation on behalf of the decedent.⁶⁸

The Vaccine Adverse Event Reporting System (VAERS) requires mandatory reporting in certain circumstances (such as by the manufacturer) and, in other cases, encourages healthcare professionals to report any clinically significant adverse event related to immunization to VAERS.^68,69 Regarding adverse events following influenza vaccination, reportable events required to be submitted to VAERS include anaphylactic shock, shoulder injury related to vaccine administration, vasovagal syncope, Guillain-Barré, acute complications (including death), and contraindication-associated events described in the package insert.⁶⁹

Vaccination Adverse Reactions

The incidence of adverse events of interest varies by vaccine type.⁶⁸ One study reported that trivalent vaccines were associated with fewer adverse events of interest than quadrivalent influenza vaccines, but more adverse events of interest than the quadrivalent live attenuated influenza vaccine for children.⁷⁰

Pain and other injection-site reactions, such as redness and swelling, may occur after receiving the influenza vaccine.^71,72 These typically resolve within a few days but may temporarily affect the ability to do daily activities. Some individuals may get a fever, malaise, myalgia, and other systemic symptoms.^71,72 Allergic reactions, ranging from mild to severe, including anaphylaxis, have also occurred. When administered with the 13-valent pneumococcal conjugate vaccine and the diphtheria, tetanus, and pertussis vaccines, egg-based inactivated influenza vaccines have historically been associated with febrile seizures in young children.⁷¹ Syncope has also been reported with injected vaccines, and providers should encourage patients to stay seated and to be observed for 15 minutes post-vaccination to decrease the risk of injury should they faint.⁷²

Anaphylaxis Preparedness and Response

The CDC states: “All vaccines should be administered in settings in which personnel and equipment for rapid recognition and treatment of anaphylaxis are available. ACIP recommends that all vaccination providers be certified in cardiopulmonary resuscitation (CPR), have an office emergency plan, and ensure that all staff are familiar with the plan.”⁶⁸

If vaccinations are administered and an allergic reaction occurs, it is essential to either call 911 and have an ambulance ready or send the patient directly to the emergency room. Epinephrine should be administered; however, further monitoring is beyond the scope of this course. Ensure that you communicate any relevant information to the emergency medical technicians or emergency department staff, including the vaccine the patient received and any treatment you provided.⁶⁸

Vaccine Resources Influenza surveillance, prevention, and control information is available on the CDC website: Influenza (Flu). CDC https://www.cdc.gov/flu.73 Surveillance data is updated weekly on FluView at https://www.cdc.gov/fluview/index.html74 National, regional, and state-level outpatient illness and viral surveillance may be found at FluView Interactive ILI and Viral Surveillance https://www.cdc.gov/fluview/overview/fluview-interactive.html?CDC_AAref_Val=https://www.cdc.gov/flu/weekly/fluviewinteractive.htm75 CDC-INFO is available at 1-800-232-4636 for health professionals and pharmacists to provide additional information

Emerging Vaccine Strategies

Research is ongoing for new influenza vaccines that offer broader and longer-lasting protection. These include mRNA vaccines, which have shown promise in clinical trials.⁷⁶ The U.S. Department of Health and Human Services (HHS) and the National Institutes of Health (NIH) have launched the "Generation Gold Standard" initiative, a groundbreaking next-generation universal vaccine platform utilizing beta-propiolactone (BPL)-inactivated whole-virus technology to deliver broad-spectrum, long-lasting protection against pandemic-prone viruses, including H5N1 avian influenza and coronaviruses like SARS-CoV-2, SARS-CoV-1, and MERS-CoV.⁷⁷

Summary

Influenza is a common contagious respiratory illness that affects millions of people every year. Influenza is caused by the influenza virus, which is transmitted through contact and/or inhalation of infected droplets. The virus is spread through coughing, sneezing, spitting, or touching contaminated environmental objects or surfaces with hands.

Outbreaks of influenza occur every year, typically during the winter months in the Northern Hemisphere. Environmental and social factors are the primary causes of seasonal outbreaks. Changes in the antigenic profile of the influenza virus are responsible for the annual occurrence of outbreaks. Most cases of influenza are mild and self-limiting. People who contract influenza typically have a cough, fever, and malaise for a few days, then recover completely. However, serious complications and death are possible, particularly in high-risk populations, such as the very young, the very old, and people who have coexisting medical comorbidities.

The CDC website is an invaluable source of information about seasonal influenza. The CDC publishes up-to-date information about influenza, including the strains affecting the population, recommended vaccines, and proper storage and handling procedures. Vaccination is recommended for everyone at 6 months of age or older. Vaccination is particularly important for individuals and/or cultural groups at risk of severe influenza or its complications, as well as for those who work with vulnerable populations. Pharmacists and pharmacy technicians play a crucial role in the fight against influenza by providing vaccinations and educating the community about the disease.

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