Helen L. Regnery,

Helen L. Regnery,

A weeklong electronic journal.
Feb. 3 1998 3:30 AM

Helen L. Regnery,

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       The big news of the day: Everyone is back from the FDA advisory meeting in Washington and all is well. The strains of influenza that make up the vaccine each year must be decided upon before March so that the vaccine manufacturers have sufficient time to prepare the vaccine plus distribute it by early fall. The vaccine is made up of three separate viruses to cover the three viruses that have been circulating in the human population since 1968. These viruses are called influenza A(H3N2), A(H1N1), and B and could be considered analogous to three families. Because flu viruses continue to try to outsmart us, there are different strains (new children, if you like) continuously being born within each family. It is these strains (children) that we need to identify quickly and use to prepare the vaccine before they spread throughout the population.
       There are actually two meetings before the final selection of strains is made. At the FDA advisory panel meeting, usually, the first strain is chosen. Then, about two weeks later, a second meeting occurs in Geneva. The Geneva meeting is a World Health Organization meeting and is composed of four major laboratories with sites around the globe, so that information can be presented from most areas of the world. Of course, our own Influenza Branch of the CDC is one of the four. So although there is a short breather, it is not over until the final decision is made in Geneva.
       Back to the big news of the day. The FDA advisory panel selected the same strain for influenza B as was in the vaccine last year. This happened simply because there were not sufficient data to warrant changing the strain. The panel seldom elects to choose another component, since it is usually best to consider the additional data that can be collected during the next two weeks and important to know how the global data may affect the United States. After all, influenza is a global disease. However, this year the FDA advisory panel felt there was enough evidence to support the selection of a second strain. This newly chosen strain belongs to the A(H3N2) family. This influenza season in the United States, there appeared a new member of the family, called A/Sydney/05/97. This virus was first identified in Australia and New Zealand in June. Too late to include it in this year's vaccine, but it will be in next year's. However, since Sydney is a close cousin of the A(H3N2) virus in our vaccine, it is not as though the vaccine is bad or doesn't cover this new virus. It means that there may be less than optimal coverage, but there will be partial coverage. Besides, both the virus in the vaccine (Wuhan) and the Sydney virus have been circulating in our population this year. So even if Sydney could have been in the vaccine this year, the other circulating strain would not have been. Sometimes you cannot make a home run and must be satisfied with third base.
       A review of the outbreak of influenza A(H5N1) in Hong Kong was also presented to the panel. There have been no new cases with onset since Dec. 28. Only time will tell us whether or not this will be a repeat event or whether the virus will adapt itself to humans and become a serious global threat. If there is anything good about the outbreak of the H5 virus, it is that we now know the gaps in our system that slow down the response process. It is the hope that the "powers that be" now realize that our organization has to be strengthened if we are going to be able to respond to such a public-health threat in the future. Good day.

Helen L. Regnery is a flu specialist at the Centers for Disease Control and Prevention.