Letter from the Commissioner to Nation's Doctors on H1N1 Vaccine

[indigo girl]

First, scientists at laboratories in the United States and elsewhere modified the 2009 H1N1 virus into a version suitable to be used as the “seed” for the development of vaccines. The process that was followed is similar in every respect to that which is employed every year for the preparation of seasonal influenza vaccines, as slightly different strains appear regularly each year. For the 2009 H1N1 virus, modified strains suitable for vaccine manufacturing were created and provided to influenza vaccine manufacturers by late May.

Next, companies began manufacturing the 2009 H1N1 vaccines in the same factories where they are licensed to manufacture seasonal influenza vaccines – using the same equipment and the same testing procedures. FDA inspects these plants at least once a year to assure that quality controls are followed at every step in the production process. FDA’s oversight covers both those facilities that make the inactivated vaccines (the “flu shot”) and those that make live attenuated viral vaccine (the “nasal spray”).

A critical part of influenza vaccine production is the growth of the vaccine strain in specially produced eggs. After inoculation of the eggs, the virus replicates, creating hundreds of thousands of copies of itself. It is the efficiency of this growth that determines how much vaccine can be produced and how quickly. The material harvested from these eggs is then further processed into the vaccines that you administer to your patients.

The agency found that all of the appropriate documentation had been submitted, and all of the standards had been met. In fact, had this new virus emerged a few months earlier, it could have been included as one of the three strains in the 2009 seasonal vaccine. In this key respect, although the strain of the 2009 H1N1 virus is new, the 2009 H1N1 influenza vaccines are not.

Over the summer, the National Institutes of Health and vaccine manufacturers initiated clinical trials to determine the dose and number of doses needed to induce an optimal immune response. The good news is that just as for seasonal vaccine, one dose of H1N1 vaccine will likely be protective for healthy adults, the elderly, and older children. For children ages nine and younger, two doses of the H1N1 vaccine will likely be optimal, also similar to seasonal vaccine. No serious adverse events attributable to the vaccine have emerged during the clinical trials, which have so far included over 3600 patients at NIH-supported institutions alone.

We are not cutting any corners. Just as for seasonal influenza vaccine, no lot of the 2009 H1N1 vaccine can be used until it has been carefully evaluated and released as sterile and potent by both the manufacturer and by the FDA.

(hat tip Avian Flu Diary)

Please read the whole letter at: http://www.fda.gov/NewsEvents/PublicHealthFocus/ucm189691.htm