Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: FRIDAY, March 20, 1992 TAG: 9203200144
SECTION: NATIONAL/INTERNATIONAL PAGE: A-1 EDITION: METRO
SOURCE: The Washington Post
DATELINE: WASHINGTON LENGTH: Medium
Scientists at the Food and Drug Administration choose the final formula for next season's influenza vaccine well in advance. If they choose well, a $15 flu shot will offer substantial protection. It will even save lives. But if they choose poorly, the flu shot will be little better than a sharp stick in the arm.
The formula amounts to a gamble because nobody really knows what "strains" of influenza virus will make people sick eight months from now. That uncertainty, however, will not keep FDA scientists from making their best bets, and drug companies from taking those bets and turning them into $100 million worth of influenza vaccine.
The demand for flu shots rises each year, as public health officials and many physicians urge their use by persons over 65 and those with chronic illnesses. This winter's experience is expected to drive demand even higher.
Influenza arrived in most of the country at the end of November, about a month earlier than usual. The illness was harsher, and its mortality higher, than in most years. Many clinics and physicians' offices ran out of flu shots.
Last year, about 38 million doses were made, up from 23 million in 1985. The four U.S. manufacturers - Connaught Laboratories, Parke-Davis Sterile Products, Wyeth-Ayerst Laboratories and Lederle Laboratories - are markedly boosting production for next season.
Though influenza rarely is fatal itself, it contributes substantially to the mortality of the elderly and people with chronic illnesses, who often die of complications such as pneumonia. Influenza and pneumonia - the two are listed together in death statistics gathered by the government - are the sixth-leading cause of death in the country.
A typical example of influenza's danger was recently described in a report from the Centers for Disease Control. Sixty-five residents of a New York nursing home came down with flu. Half developed pneumonia. Nineteen had to be admitted to the hospital, and two died.
Unlike the agents of most infectious diseases, the virus that causes influenza evolves in important ways every year. A shot designed to protect against this winter's flu is not likely to help against next winter's.
But because it takes six months to make the vaccine, by the time flu season arrives, it's too late to make a shot that works. Consequently, the only option is to predict long in advance of the flu season what strains of virus will cause illness.
This is the season of prediction.
Since January, scientists from the FDA and CDC have been studying virus samples from around the world, looking for strains that have just evolved and for those previously encountered but now spreading widely. With advice from a panel of academic scientists, the government officials make three selections from this long and varied "menu" of viruses. That number is needed because three general types of influenza virus can cause human illness. Two are in the family designated influenza A, and the third is the family designated influenza B.
Once chosen, samples of the viruses are sent to the drug companies, which grow them on an industrial scale. Measured amounts of the three strains - after being purified and chemically inactivated so they cannot cause illness - are combined. The resulting mixture is the vaccine.
In practice, the FDA picks the three components over a period of about six weeks.
Staggering the decisions allows manufacturers to begin production on one component while the formulators wait for more information on the others.
"It would be nice if we could wait until April, until the influenza season is over, to come up with the formula," said Roland Levandowski, an FDA scientist. "But it's just not practical."
A case in point occurred in 1986.
In April that year, a strain of virus was isolated in Taiwan that looked "new" and virulent, a good candidate for vaccine. But the formula already had been decided. So the FDA recommended that manufacturers produce a small batch of supplement, to be given to especially high-risk people.
The choice was both right and irrelevant. The Taiwan strain caused 99 percent of flu in the United States the next year. But by the time the supplemental vaccine was ready, the season was nearly over. Most of the shots were returned to the manufacturers unused.
Simultaneous with the American deliberations are similar ones in Geneva, headquarters of the World Health Organization. The latter's vaccine formula is usually the same as the FDA's, and is followed by European manufacturers.
Epidemiologists estimate that in a normal year, about 500 million people, or 10 percent of the world's population, contract influenza. In years of pandemic, the number is in the billions.
by CNB