Should you vaccinate HCWs against smallpox?
CDC expert: You’ll have 3-4 days after exposure
Imagine a patient who comes to the emergency department (ED) with a rash, pustules, high fever, and delirium. Lab tests show this isn’t a bad case of chickenpox; it’s smallpox. Everyone who came into close contact with the patient — including ED staff — now is at risk for contracting the disease.
That potential scenario has led some to advocate widespread vaccination of health care workers. But those workers could be protected with vaccination within three or four days of exposure, says Bill Jarvis, MD, associate director for program development at the Atlanta-based Centers for Disease Control and Prevention’s (CDC) Division of Healthcare Quality Promotion. "You have time to be vaccinated and respond before you get smallpox," he says, adding that smallpox isn’t as contagious as chickenpox.
The Interim Smallpox Response Plan and Guideline (www.cdc.gov/nip/diseases/smallpox) calls for a contact-based approach to vaccination after a smallpox case has been confirmed. According to the guidelines, which are still in draft form, priority for vaccination would include "[people] involved in the direct medical care, public health evaluation, or transportation of confirmed or suspected smallpox patients," and "other [people] who have a high likelihood of exposure to infectious materials [such as personnel responsible for hospital waste disposal and disinfection]."
Hospitals should focus their resources on other aspects of preparedness, such as building disaster response teams and determining who would be activated to respond to a bioterrorism event, Jarvis says. "They should not focus as much on vaccination as on preparedness," he says.
Can we stockpile enough doses?
CDC is developing a federal action plan for smallpox, which includes the stockpiling of some 300 million doses of vaccine — enough to cover the entire population. Some people may need to be vaccinated preemptively, such as a special SWAT team at CDC that would respond to first reports of suspected smallpox, Jarvis says. Hospitals should identify the staff most likely to come into contact with smallpox, such as infectious disease specialists and ED staff. They would be the first to receive a vaccine, if it is recommended, he says. "You don’t want to vaccinate a bunch of people who, should an emergency occur, wouldn’t have any contact," he says.
Public health experts are concerned about the potential severe side effects related to the vaccine — including rare but possibly fatal encephalitis. "The main reason why smallpox vaccine was stopped was that the risk-benefit equation had tipped," says Jarvis. "There were more adverse events than there were smallpox cases." Those who received the smallpox vaccine before widespread vaccination was halted in 1972 are not protected against contracting the disease, but their risk of mortality is lower, Jarvis says. "If you’ve been vaccinated in the past, you probably do have some residual immunity," he says.
The response to the anthrax, recent outbreaks, and after the World Trade Center attack should reassure hospital workers that adequate supplies can be provided quickly, Jarvis says. "We’re there within eight to 12 hours of the event," he says. Meanwhile, hospitals should urge health care workers to receive the influenza and varicella (chickenpox) vaccines. "In the current state of concern about bioterrorism agents, varicella is going to be a nightmare to deal with," Jarvis says. Some cases of chickenpox may be confused with smallpox, he says.
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