The trials are being conducted “in a compressed time frame in a race against the possible autumn resurgence” of the swine flu, possibly at the same time as the regular seasonal flu, said Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, which will oversee the trials.
Only after the trials are done, which is estimated to take about two months, can health officials recommend a vaccination program. It would be voluntary and would have to be rolled out in stages because not nearly enough doses for all Americans will be ready in the fall even if there are no testing or production problems.For the trial, healthy adult volunteers will be recruited at eight sites and given one or two shots, each containing 15 or 30 micrograms of vaccines made by two different companies. Some will get the injections concurrently with seasonal flu vaccines.
If the shots seem safe in adults and the elderly, trials in teenagers and children as young as 6 months will be added.
About 2,400 volunteers will be tested in this round, Dr. Fauci said. All will be monitored for bad reactions, and, about three weeks after each shot, their blood will be tested to see how many antibodies to the swine flu were made. A high antibody level means the volunteer would not get the flu or would get only a mild case.
In such a small trial, researchers will be able to pick up only obvious problems, Dr. Fauci said. Typical side effects of seasonal flu shots include sore arms, fever and aches. (These symptoms, echoing those of mild flu, lead to the persistent but false rumor that flu shots cause flu, experts say.) Rarer but more serious side effects like hives, dizziness and breathing problems usually stem from allergies to the chicken eggs that vaccines are grown in.Researchers will also look out for Guillain-Barré syndrome, which can cause fever and serious nerve damage and muscle weakness.
The 1976 vaccination of 40 million people after a swine flu outbreak in Fort Dix, N. J., was stopped after some people developed the syndrome. But shots were never proved to have been the cause, and the syndrome may be an extremely rare reaction to any vaccination.
According to the federal Centers for Disease Control and Prevention, about one person in 100,000 develops Guillain-Barré syndrome for unknown reasons. These trials are very unlikely to pick up a side effect that rare. “You’d have to vaccinate several hundred thousand or millions of people to do that,” Dr. Fauci said.
The trials will be conducted at eight hospital and medical organizations that have been used since 1962 to test seasonal flu shots and other experimental vaccines. They include the Baylor College of Medicine in Houston, Children’s Hospital Medical Center in Cincinnati, Emory University in Atlanta, Group Health Cooperative in Seattle, the University of Iowa in Iowa City, the University of Maryland medical school in Baltimore, St. Louis University and Vanderbilt University in Nashville.
The initial tests will be of vaccines made by Sanofi-Pasteur, a European company, and CSL Biotherapies, an Australian company that has supplied seasonal flu shots in the United States for years. Novartis, the third company from which the government has contracts to buy large amounts of swine flu vaccine, is conducting separate trials for Food and Drug Administration licensing, Dr. Fauci said.
None of the first trials will test a vaccine containing an adjuvant, which is an additive, usually an oil-water emulsion, that stimulates the immune system to react more strongly. The government bought large stocks of adjuvants to stretch the vaccine supply if the flu mutates into a more dangerous form and a clamor for shots emerges.
Adjuvants, which are common in veterinary vaccines, cause more side effects and are not now used in flu shots in the United States. But they are “not off the board,” Dr. Fauci said. “We’ve developed a mix-and-match protocol for them, but we want to see the data on vaccine safety first.”
No comments:
Post a Comment