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Flu Vaccine: How it finds its way into the needle

This week is National Medical Laboratory Professionals Week and National Environmental Laboratory Professionals Week.  APHL is honoring the many individuals working public health and environmental laboratories around the world.  Stay tuned for blog posts this week featuring the work of many of those unsung heroes working to protect the public’s health.

By Stephanie Chester, MS, Senior Specialist, Influenza Programs, APHL

When you get your annual flu vaccine, chances are you roll up your sleeve, feel a small prick and go on about your day without thinking any more about the shot. Yet there is a lot of work that takes place behind the scenes to determine what’s in that injection.

Fortunately for you, the US has a system for national influenza surveillance. Data from across the US is collected to identify which flu viruses are circulating, if the current season’s vaccine is a good match, and which viruses should be included in the next year’s vaccine.

This is CDC Clinic Chief Nurse Lee Ann Jean-Louis extracting Influenza Virus Vaccine, Fluzone® from a 5 ml. vial.According to the product text, the intramuscular route of administration is recommended, vaccinating adults and older children in the deltoid muscle using a needle ? 1 inch in length in order to penetrate the muscle tissue.

Did you know that preparations for next season’s flu vaccine start at the beginning of each flu season? In fact, it is the specimens collected at the beginning of each new flu season that help inform vaccine virus selection for the next year. So how does this work exactly? Well, it is a complicated process but one in which public health laboratories play a critical role.

Let’s say you come down with a fever, cough, sore throat and other generally crummy symptoms. You decide to give in and go to the doctor who will likely test you for influenza. Some doctors act as sentinel providers which means they regularly submit specimens collected from patients with flu-like symptoms to public health laboratories for influenza surveillance. Public health labs can also receive specimens from a variety of other submitters including hospital/clinical laboratories, university student health centers, long-term care facilities, commercial laboratories and many more.

Now here’s the part that APHL staff really like to talk about: the public health lab role! The public health lab will test the submitted specimens for influenza.  They will then characterize the influenza virus down to the specific flu subtype using a real-time reverse transcriptase PCR (RT-PCR). These test results are reported to CDC and help inform what specific types and subtypes of influenza are currently circulating in the country and locally. This helps CDC and state/local public health officials determine if this year’s vaccine is effective at protecting us from what is actually circulating.

The public health lab then selects a subset of specimens to submit for national surveillance.  This subset is grown up in virus culture and further characterized to determine exactly which influenza viruses are predominant and thus should be included in next season’s vaccine. Each February, CDC, in collaboration with the World Health Organization and other countries, uses real-time RT-PCR data, sequencing analysis and viral isolate characterization results to determine which viruses to include in the Northern Hemisphere’s vaccine for the next season.

As you can see, a lot of effort goes into national influenza surveillance and vaccine virus selection, and public health labs are integral in this process. The diligent work of public health labs and their health departments ensure that specimens arrive at CDC consistently and on time to help inform vaccine virus selection.

As we celebrate Lab Week, I for one am very grateful for the hard work and dedication of all the public health lab personnel and public health officials who consistently perform exemplary work to support our national influenza surveillance system. Their work on influenza alone impacts all our lives, from informing our communities and physicians about circulating flu viruses to helping to determine what goes into that annual prick in our arm. They deserve to be celebrated! Happy Lab Week!


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