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Would old vaccine work if needed during a pandemic?

Author: Ruben Donis, Deputy Director, BARDA Influenza Division
Published Date: 3/17/2016 1:24:00 PM
Category: Public Health Preparedness; Medical Countermeasures;

One of ASPR’s goals is to protect our nation against future flu pandemics. Even before ASPR was created in 2006, our nation started stockpiling millions of doses of flu vaccine to protect Americans against the H5N1 avian flu that spread in Asia beginning in 2004.

But, would the vaccine that was stockpiled more than a decade ago still be safe and effective to use if this pandemic flu strain spread in the U.S. today?

We believe so, but this aged vaccine has not been tested in humans, so we’re going to find out.

Unknown Shelf Lives

Most seasonal flu vaccine is stored for less than one year, so we lack data on how well flu vaccines hold up over time – basically, how long their shelf lives are. We know the potency of most vaccines diminishes over time. A recent study found that the active ingredient (antigen) of one of the stockpiled flu vaccines stored for five years remained safe and elicited an immune response in people, but was only about half as potent as it was when it was produced. In the world of vaccines, the difference between five and ten years is significant.

The active ingredients (in bulk) for strains of H5N1 flu vaccines maintained in the National Prepandemic Influenza Vaccine Stockpile undergo laboratory testing several times a year since they have been produced, and have been found to be within 60 to 90 percent of their original potency from when they were first stockpiled seven to nine years before. While this monitoring by testing in the laboratory has suggested they should still be effective, what we don’t know is whether they would still elicit a comparable immune response if they were to be used today.

Finding the answer to this question will help inform us about the national prepandemic influenza vaccine stockpiling strategy, including how long some antigens might be stored and still be usable.

BARDA Paving a Path to Find the Answers

BRITE is important in that it will answer this vital question. It is also a historic study in that it represents the first clinical trial that BARDA has sponsored and supported completely on its own.

The clinical study will seek to determine not only whether the stockpiled A/Vietnam/2004 (H5N1) lots of vaccine antigen produced in 2004 and 2005 still elicit immunity, but also whether the adjuvant produced in 2009 and 2013 has maintained its safety and potency. An adjuvant is an ingredient of a vaccine that helps create a stronger immune response in the patient’s body.

The study is expected to include more than 400 participants at six locations across the U.S., and the first 65 participants enrolled on March 15. After following the participants for a year, BARDA will know whether this vaccine passes the real world performance test by Fall 2017.

Additional Post-Study Benefits

BARDA could see benefits from managing this clinical trial beyond simply providing the answers it is designed to yield.

Clinical trials are required to assess the safety and efficacy of new medical countermeasures. By expanding our in-house expertise within BARDA to manage clinical trials, then this increased capacity could be tapped during an emergency to help develop new countermeasures when a third party might not be available to respond to those immediate needs.

Having this high level of proficiency within BARDA will help us more effectively engage with partners to conduct clinical studies, improving our ability to respond quickly to emergencies and better protect our nation.


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