The Smallpox Conundrum
That's the best way to protect ourselves against a bioterrorist attack?
Public health officials in Tulsa, Okla., recently ran a smallpox preparedness drill--practicing what they would do to stop the spread of this deadly disease in the case of a bioterrorist event. The drill is just one part of a plan that Tulsa's health department, like many others around the nation, submitted last week to the federal Centers for Disease Control and Prevention, just days before President Bush announced that the United States would resume smallpox vaccinations for the first time in three decades.
Bush's statement marks a dramatic shift in U.S. smallpox strategy. He has ordered that key military units be inoculated, and Bush himself will receive the vaccine with them. Then "first responders" such as ER doctors, nurses, and emergency personnel will be vaccinated. The president has not recommended vaccinations for the general public. However, if people demand it, Bush says health officials should vaccinate them.
Until now, smallpox preparedness has relied on so-called ring vaccination-- containing an outbreak by rapidly isolating and vaccinating people who had close, face-to-face contact with the victim. "Contacts" vaccinated in three to seven days after exposure may escape smallpox or suffer a light case. In the Tulsa drill, officials identified nine "confirmed" smallpox cases, traced 2,900 "contacts," and sent 255 people for immediate mock "vaccination." Tulsa needed between 500 and 1,000 officials to make this work. No public health official really knows what it would take if there were many cases occurring simultaneously in half a dozen cities. Says Patrick Libbey, executive director of the National Association of County and City Health Officials: "To vaccinate an entire population within five days--we may not make it."
A smallpox attack is still considered a very unlikely event. The United States and Russia are the only two countries that officially have the virus, but scientists and intelligence agencies fear other nations, such as North Korea and Iraq, may have secret smallpox stores that could be used as biological weapons. The public seems to share in this anxiety. Indeed, almost 6 in 10 Americans worry that terrorists will use smallpox in an attack on the United States and 65 percent say they would be vaccinated. Despite public anxiety, however, and over $1 billion in federal bioterror funding appropriated in 2002, most health departments are still begging for the dollars needed to properly prepare for a smallpox attack. The slumping economy has left Rex Archer, health director in Kansas City, Mo., with fewer rather than more people he could press into service to stop a smallpox attack. The same thing seems to be happening all over the country as state health budgets shrink. Archer estimates that most health departments have less than 10 percent of the staff they would need to stop the spread of smallpox using only a ring approach.
Unnatural. Planning for a smallpox event can be complicated because the virus, which is transmitted in saliva, would likely be spread not only in the natural way--to friends or family members of the sick--but also intentionally, in a manner no scientist has studied well. "We know a lot about the natural spread of smallpox from the past," says Walter Orenstein, director of the National Immunization Program at the CDC. "But now I think the states have to be prepared to do mass vaccination to deal with the unnatural spread of the disease."
Vaccinating before any release of smallpox virus offers certain protection for three to five years. After that, immunity wanes, but the vaccine still diminishes severe disease and death. Most states will start by vaccinating healthcare workers: Past studies have shown that half of the spread of smallpox occurs in hospital settings and that 1 in 5 who gets the disease is a healthcare worker.
There is also the question of who will get what vaccine. Dryvax, the older, dried vaccine that is currently available in the U.S. stockpile and was recently relicensed, is highly effective even when diluted. But it also has some fairly significant side effects, particularly for people at high risk of complications. Life-threatening reactions occur in about 52 people among 1 million vaccinated and include encephalitis, in about 12 per million vaccine recipients, and eczema vaccinatum, a reaction where the vaccinia virus spreads beyond the vaccination site. Eczema vaccinatum requires prompt and massive treatment with an antibody to vaccinia virus, made from the plasma of recently vaccinated donors. Right now there are only about 600 to 800 doses of this antibody in the United States. What's more, only some life-threatening reactions can be treated, which means that 1 or 2 people in a million will die from getting a smallpox vaccination. Less severe reactions--fever, rashes, sore arms, muscle aches--are common. Among young, healthy volunteers participating in a trial to determine the effectiveness of diluted Dryvax, 36 percent of those vaccinated felt sick enough to miss work or school.
Fear of sharing. Unless there is a massive outbreak, some others would also be advised to skip the inoculation: people with weakened immune systems, cancer, or AIDS, those who've received radiation treatments or organ transplants, pregnant women. Nor should their regular household contacts be vaccinated, because they could inadvertently spread the live virus from the vaccination site on their arm. Indeed, this inadvertent spread of virus is the most common complication of the smallpox vaccination. A semipermeable dressing covering the vaccination reduces the risk.
Last winter, the government ordered 209 million doses of a new smallpox vaccine from Acambis Inc. that is due to arrive soon. Testing and licensing the new vaccine should be completed by 2004. Many experts believe the Acambis vaccine will be safer than Dryvax, since it's grown in lab cultures rather than derived directly from the skin of calves.
Next comes the long-awaited campaign to educate citizens, and doctors, about the risks and benefits of voluntary vaccination. "During the anthrax experience, I saw a lot of people treated for anxiety with unnecessary antibiotics," says Susan Allan, director of health for Arlington County, Va. "I hope we won't see doctors treating patients for anxiety with a risky vaccine."
This story appears in the December 23, 2002 print edition of U.S. News & World Report.