Last Updated

14 Dec 2002

Source:  Reuters, March 4, 2002.

Can Anthrax Vaccine Make You Sick? Jury Still Out

By E. J. Mundell

NEW YORK (Reuters Health) - Early results from a nationwide US database for vaccine-associated side effects suggests no clear pattern of illness associated with the anthrax vaccine, experts reported here Sunday.

However, the researchers caution that a much larger sample needs to be collected before the existence of any vaccine-related syndrome can be ruled out.

Investigation in the vaccine remains "an ongoing process," said Dr. Bryan L. Martin of the Walter Reed Army Medical Center in Washington, DC. "It's a continuum," he said. "This will continue to become better and better data as we use the vaccine more and more."

Martin and co-researcher Dr. Renata Engler presented their findings as part of the annual meeting of the American Academy of Allergy, Asthma and Immunology.

Controversy continues to surround the military's use of the anthrax vaccine, which some experts believe to be both ineffective and potentially harmful to recipients. In January, the Department of Defense advised that pregnant servicewomen not receive the shot due to inconclusive data that it might be linked to an increased risk for birth defects.

In their report, Martin, Engler and colleagues examined data from the Vaccine Adverse Events Reporting System (VAERS)--a nationwide database, sponsored by the US Centers for Disease Control and Prevention and Food and Drug Administration. The system acts as a reporting center for patients who believe they may have experienced illness linked to the administration of a particular vaccine.

Out of more than 2 million doses of anthrax vaccine given to over 520,000 US military personnel since 1998, an independent review panel found just 82 cases of severe "adverse events" -- resulting in hospitalization or prolonged disability -- that they deemed might be caused by the anthrax vaccine.

While patients experienced a variety of symptoms, ranging from persistent headache, skin rash, ringing ears or prolonged fatigue, no consistent pattern of illness emerged.

Symptoms were "very diverse," Engler told Reuters Health. "They are clustered together a little bit, but as you can see they are very small numbers."

She stressed, however, that this does not mean that a larger sample wouldn't uncover a distinct pattern suggestive of an anthrax vaccine-related syndrome. "We can't prove or disprove causality at this point in time," she said, adding that researchers "need to be open" to all possibilities.

"But at the present time, in terms of the more serious things -- talking here about hospitalizations, profound disability -- the rates are very, very low, just like with other vaccines," Engler explained. "If you're talking about local reactions -- swollen arms or flu-like symptoms for a few days -- that's very common, but its also common with other vaccines."

A much larger sample -- perhaps around 10 million doses -- might be needed before numbers become large enough to draw more definite conclusions.

"If around the world there came to be hundreds of similar cases that had been reported to the VAERS system, then we'd begin to make that association," Martin said.

The researchers stressed that patients and physicians must work together to report any vaccine-associated symptoms to VAERS, since, typically, current reporting only uncovers about 10% of adverse events. "Patients should go and ask their doctor 'Hey, you know, I'm concerned, I have a question, can you help me report this?" Engler advised.

In the meantime, research is under way to reduce risks for local reactions -- such as swollen injection sites -- to help allay public fears. One such study suggests that a reduced dose of the vaccine, injected into muscle rather than just under the skin, can nearly eliminate local reactions.