Flu Vaccine Particulars for Advanced Practice Clinicians

As the flu season ramps up and influenza vaccine administrations ensue, clinicians may be hearing an assortment of comments from patients.

As the flu season ramps up and influenza vaccine administrations ensue, clinicians may be hearing an assortment of comments from patients. “So, do you think they got it right this year?” asks a patient while you prepare the injection; or you hear, “I never get the flu shot before November because I don’t want it to wear off.”

Maybe during a sick visit you recommend the vaccine to a patient and get the response, “I never get the flu shot anymore. I got it once and became so sick I will never get it again!”

Perhaps while performing a Department of Transportation (DOT) or sports physical, you recommend the vaccine and hear the comment, “I never get sick. I don’t need to get vaccinated.”

Talk about teachable moments. How a provider responds and the information they share can affect not only your patients, but also their families and communities. Do you have the knowledge to answer patients’ questions during conversations to promote health and wellness among your patients and community?

Influenza Pathogenesis

Influenza is a highly contagious disease that attacks the respiratory system in mammals of the air, sea, and land, including humans. Its pathogenic etiology is caused by a virus that is easily spread not only through respiratory droplets from host to host, but also from contact with surfaces on which the virus is still alive. The sole purpose of the virus’s existence is to infect host cells, overtake their DNA reproduction, and replicate the virus. This hostile takeover results in cell death and release of the virus by the thousands into the host’s system and the environment through coughing and sneezing. The mission of the virus is to repeat this over and over again.1,9

Through transcription and replication, the characteristics of the virus protein surface may mutate, resulting in variations from the original RNA strands. The changes may produce shifts (marked variation) and drifts (mild variation) from the original surface protein codes.2Sounds like a science fiction thriller, doesn’t it?

These properties of the influenza virus make it challenging to formulate flu vaccinations every year. Without precise antibodies to fight influenza, the body’s response to this pathogenic hijacking is inflammation, which can weaken the respiratory system and make it vulnerable to complications.2

Influenza Types

The 3 types of influenza are A, B, and C. Type C is thought to be less virulent and to manifest much milder symptoms than types A and B. Type C does not usually cause epidemics. Type B appears to be infectious mainly to humans but possesses the characteristics essential for causing epidemics due to its infectious nature and easy transmission through droplets.5

Types A and B are seasonal viruses that spread annually and can be the origin of epidemics. Their protein surface characteristics of these types constantly evolve through transcription and replication.2

Type A virus can pass between birds, animals, and humans, creating a large reservoir for disease. Type A virus is categorized into subtypes named for their surface proteins. They can be transmitted to humans by direct, adaptive, or genetic reassortment. An example of direct contact is transmission to a person from an infected bird. An adaptive transmission may start with infection of a bird that transmits the virus to a pig; during replication, changes in the virus may enable transmission to and infection of humans. In genetic reassortment, a person is simultaneously infected with 2 subtypes of A, resulting in combining of their DNA, which produces new surface characteristics. This is why last year’s vaccine might not be effective this year, and this year’s vaccine might not be effective next year.1-3

Monitoring Influenza

The 1918 influenza pandemic killed 100 million individuals and is characterized as the worst pandemic in human history. This global disease called for a global approach, so world health leaders and scientists took everything they learned from the pandemic to form the World Health Organization (WHO) Influenza Program.4

WHO orchestrates the surveillance and monitoring of influenza activity throughout the entire world. One hundred fifteen laboratories worldwide collect influenza samples for the WHO Influenza Program. The samples are sent to 1 of 6 WHO collaborating centers in Japan, Australia, England, China, or the United States.1,6,7

In the United States, the Centers for Disease Control and Prevention (CDC) has 2 WHO collaborating centers: one in Atlanta, Georgia, and one in Memphis, Tennessee. The centers identify and classify the viruses, tracking any changes (shifts and drifts). Then, through a formal collaborative process, scientists meet twice yearly to compare strains that are on the rise or are dominating flu activity. That information is passed from the US centers to manufacturers. After the strains are identified, the information is sent to licensed flu vaccine manufacturers in order to produce influenza vaccines for millions of individuals.2,6

Influenza Vaccine Production

In the United States, only licensed private manufacturers are allowed to produce the influenza vaccine. The process is highly complex and highly regulated. This year, 6 manufacturers are producing several flu products for distribution, including live attenuated virus in a nasal spray vaccine, a highdose vaccine for individuals 65 years or older, an intradermal vaccine, and an intramuscular injection vaccine, which is most common.8

In 2005, President Bush enacted the National Strategy for Pandemic Influenza by the Homeland Security Council. This enabled research and development of new processes for producing flu vaccine in mass quantities. In 2013, the FDA approved 2 new processes to increase the supply and availability of flu vaccine.3

For almost 80 years, flu vaccine has been produced through egg incubation— growing viruses inside eggs. Millions of eggs are needed for this process. After a virus is allowed to grow in an egg, the virus is collected, isolated, refined, inactivated, tested, and retested. After approval from the FDA, the vaccine is placed in vials and syringes for distribution. The process is effective but time-consuming.3

A new technology for vaccine production is cell-based technology. It purportedly shortens production time, with pros and cons, compared with traditional egg vaccine production. Cellbased technology uses mammal cells to incubate and grow the virus, which is then harvested and purified before distribution. The cells may be frozen for storage, and this method does not depend on the sometimes unreliable egg industry.3

Another vaccine production method uses recombinant technology. Patients with true egg allergies seek this vaccine because it is made without eggs. To drastically simplify the process, the proteins of influenza viruses are combined with the proteins of insect viruses and allowed to reproduce in insect cells. The virus undergoes extraction, purification, and distribution after FDA approval.3,6


A little history can enrich our lives. Knowledge of influenza history can help health care providers and their patients understand the importance of flu prevention programs. The CDC identifies a few best practices: vaccinate high-risk individuals, vaccinate patients during routine office visits, make vaccination an annual friend or family event, share what you know, and dispel myths.5,8,9

Robin Hudson, DNP, FNP-BC, has been a health care provider for more than 20 years. She graduated from Lakeview College of Nursing with a BSN, Indiana State University in the FNP track in 2008, and also received her doctorate of nursing practice there in 2015. She has worked 3 years in family rural practice and more than 2 years in the convenient care clinic setting, increasing access and delivering high-quality care at MinuteClinic.


  1. WHO: Influenza, an unpredictable threat. https://www.youtube.com/watch?v=yhhJfT86Bgg. August 10, 2015. Accessed November 19, 2015.
  2. Hannoun C. The evolving history of influenza viruses and influenza vaccines.Expert Rev Vaccines. 12(9):1085-1094. http://www.medscape.com/viewarticle/812621. Accessed November 19, 2015.
  3. Milián E, Kamen AA. Current and emerging cell culture manufacturing technologies for influenza vaccines.Biomed Res Int.2015. http://www.hindawi.com/journals/bmri/2015/504831/. Accessed November 19, 2015.
  4. Barry JM.The Great Influenza: The Story of the Deadliest Pandemic in History. NewYork, NY: Penguin Books; 2005.
  5. Grohskopf LA, Sokolow LZ, Olsen SJ, Bresee JS, Broder KR, Karron RA. (2015). Prevention and control of influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices, United States, 2015—16 influenza season.Morbidity and Mortality Weekly Report. 64(30):818-25. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6430a3.htm. Accessed November 15, 2015.
  6. How influenza (flu) vaccines are made. CDC website. http://www.cdc.gov/flu/protect/vaccine/how-fluvaccine-made.htm. Updated January 6, 2015. Accessed November 19, 2015.
  7. Global Influenza Programme. WHO website. http://www.who.int/influenza/en/. Accessed November 15, 2015.
  8. Influenza (flu): information for health professionals. CDC website. http://www.cdc.gov/flu/professionals/index.htm. Updated October 27, 2015. Accessed November 19, 2015.
  9. Clinical signs and symptoms of influenza. CDC website. http://www.cdc.gov/flu/professionals/acip/clinical.htm. Updated January 26, 2015. Accessed November 19, 2015.

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