What Happens Behind the Scenes before You Receive Your Flu Vaccine

By: Maureen Hess, MPH, RD

You probably think about influenza once a year — during the winter months when flu season rolls in as it does every year. But, for FDA, it’s a year-round initiative; we are on the front lines of making sure there is an adequate supply of safe and effective vaccine every year. And even though the current flu season is just getting started, we are already making preparations for next year.

Woman getting flu shotVaccination is the single best way to prevent influenza. Influenza is a contagious respiratory disease caused by a number of different influenza viruses, infecting the nose, throat and lungs. Even if you are healthy, you can pass the influenza virus to someone else one day before symptoms begin, and, you can continue to infect others up to five days after getting sick. Therefore, it’s possible for a healthy person to unknowingly spread the virus.

Preparing for influenza season each year is a time-critical, highly orchestrated, collaborative effort by FDA, the Centers for Disease Control and Prevention (CDC), the World Health Organization (WHO), vaccine manufacturers, and the public health community.

FDA is at the center of the process. Working with the WHO and CDC to review disease surveillance and laboratory data, and with the input of our advisory committee, we select the three influenza strains for the vaccine that will be made available in the United States. Once the strains have been selected, work continues to get vaccine manufactured and distributed well before influenza season starts. We inspect the manufacturing facilities and we prepare and provide the reagents used by vaccine manufacturers to verify the vaccine’s identity and strength.

FDA also evaluates each manufacturer’s vaccine each year for approval and conducts lot release, that is, we perform certain tests and review the results of the manufacturers’ tests on the vaccines prior to vaccine distribution. And, we continue to monitor the safety of the vaccines once they are distributed and used to vaccinate the public. The manufacturing demands are tremendous, especially since a new vaccine must be  manufactured each year. And, this new vaccine contains not just one but three new vaccine components each year, specifically, the three strains of influenza virus within the seasonal vaccine: one influenza A (H3N2) virus, one influenza A (H1N1) virus, and one influenza B virus.

Why is FDA focused on influenza? Influenza seasons are unpredictable and present a serious public health issue. Vaccination is one of the most important ways to prevent influenza. Influenza can cause various symptoms, which may include fever, cough, sore throat, headache, body aches and chills and tiredness. And the disease can range from mild to serious: over a 30 year period between 1976 and 2006, estimates of seasonal influenza-associated deaths range from a low of about 3,000 to a high of about 49,000 people.

Vaccines to prevent seasonal influenza have a long and successful track record of safety and effectiveness in the United States. The vaccine won’t give you the flu, and not only should it protect you from getting sick, it can also make your illness milder if you are exposed to a different influenza virus strain that’s not included in the vaccine.

Have you gotten your flu vaccine? It’s not too late!

Maureen Hess, MPH, RD, is Health Science Advisor, Office of Vaccines Research and Review, in FDA’s Center for Biologics Evaluation and & Research

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