This is according to studies published in Wednesday’s Journal of the American Medical Association.
“The really important news is that it is possible to conduct a mass smallpox vaccination in a safe and effective manner,” said study author Dr. William Winkenwerder Jr., the assistant secretary of defense for health affairs.
An editorial accompanying the studies said the results help alleviate concerns that surfaced when the government began smallpox programs for the military and some health care workers as part of terrorism preparedness efforts. Routine smallpox immunization in the United States ended in 1972.
“The observation that this smallpox vaccine can be administered safely in a 21st century population with a very low adverse-event rate is a critically important piece of new information,” Drs. Anthony Fauci and Mary Wright of the National Institute of Allergy and Infectious Diseases wrote in the editorial.
Despite the findings, the future of the civilian immunization program continues to be in doubt. A federal advisory panel on June 19 recommended against expanding the smallpox program to millions of emergency workers because of concerns about heart inflammation.
The panel cited at least 18 suspected cases among some 37,000 civilian health care workers vaccinated so far. All heart inflammation patients immunized through the Pentagon’s program recovered and are being evaluated to see whether there are any lasting effects.
The other possible side effects from smallpox vaccine include soreness at the injection site, fever and muscle aches. Less common but more serious reactions include a widespread skin rash, and, even more rarely, encephalitis, an inflammation of the brain. Government data show only one civilian and one military case of encephalitis were reported through May.
The overall rate of side effects in the military was largely below the rates reported before 1972, one of the studies found.
Myopericarditis causes inflammation of the heart muscle and the fibrous tissue that envelops the heart. The ailment probably occurred during smallpox vaccination in the 1960s, too, but was under-recognized because diagnostic technology was less sophisticated, military officials say.
Eight other heart-related events occurred shortly after vaccination in the military program, including four heart attacks, one of them fatal.
While military doctors think those were not related to the vaccine, the risk prompted government officials to recommend against giving the shots to people with heart conditions or strong risks of heart disease.
The Pentagon’s vaccination program exempted pregnant women, people with weakened immune systems and those with chronic skin diseases.