Monday, September 28, 2009
More than 3,000 people a day have a heart attack. If you're one of them the day after your swine flu shot, will you worry that the vaccine was to blame and not the more likely culprit, all those burgers and fries?
The government's system to track possible side effects of mass flu vaccinations will begin next month, aimed at detecting any rare but real problems quickly, and explaining the inevitable coincidences that are sure to cause some false alarms.
"Every day, bad things happen to people. When you vaccinate a lot of people in a short period of time, some of those things are going to happen to some people by chance alone," said Daniel Salmon, a vaccine safety specialist at the Department of Health and Human Services.
Health authorities hope to vaccinate more than half of the population in just a few months against swine flu, which doctors call the 2009 H1N1 strain. Vaccination is voluntary, and how many get it depends partly on confidence in its safety.
"The recurring question is, 'How do we know it's safe?' " said Gregory Poland of the Mayo Clinic.
Enter the intense new monitoring. On top of routine vaccine tracking, there are these government-sponsored projects:
-- Harvard Medical School scientists are linking large insurance databases that cover as many as 50 million people with vaccination registries around the country for real-time checks of whether people see a doctor in the weeks after a flu shot and why. The huge numbers make it possible to quickly compare rates of complaints among the vaccinated and unvaccinated, said the project leader, Richard Platt, Harvard's population medicine chief.
-- Johns Hopkins University will direct e-mails to at least 100,000 vaccine recipients to track how they're feeling, including the smaller complaints that wouldn't prompt a doctor visit. If anything seems connected, researchers can call to follow up with detailed questions.
-- The Centers for Disease Control and Prevention is preparing take-home cards that tell vaccine recipients how to report any suspected side effects to the nation's Vaccine Adverse Event Reporting system.
"We don't have any reason to expect any unusual problems with this vaccine," said Neal Halsey, director of Hopkins's Institute for Vaccine Safety, who is directing the e-mail effort.
Health authorities will have to tell quickly if there seem to be more cases of a particular health problem than usual. So the CDC is racing to compile a list of what's normal: 25,000 heart attacks every week; 14,000 to 19,000 miscarriages every week; 300 severe allergic reactions called anaphylaxis every week.
Any spike would trigger a quick investigation to see whether the vaccine increases risk and by how much, so health officials could issue warnings.
Very rare side effects by definition could come to light only after large-scale inoculations begin -- making this the year scientists may finally learn whether flu vaccine is linked to Guillain-Barr? syndrome, an often reversible but sometimes fatal paralysis. It sometimes occurs after viral infections.
But the vaccine concern stems from 1976, when 500 cases were reported among the 45 million people vaccinated against that year's swine flu. Scientists never were able to prove that the vaccine increased the risk. The CDC maintains that if the seasonal flu vaccine is related, the risk is no more than a single case per 1 million vaccinated.
However the flu season turns out, the extra vaccine tracking promises a lasting impact.
"Part of what we hope is that it will teach us something about how to monitor the safety of all medical products quickly," said Harvard's Platt.