you gonna get your shot?
The vaccine was created in 1796. The vaccine used today is essentially the same, Offit says. "We tend to think of vaccines as being very safe and every effective, which they are. But all the vaccines that we use today are the result of modern technology. That's not true of the smallpox vaccine. It has a side effect profile that we, we would not accept for vaccines today," he says.
The smallpox vaccine is made from a weak biological cousin of the smallpox virus. When you get vaccinated with the weaker virus, you become immune to the smallpox virus.
But once in a while, the vaccine does more harm than good. If you scratch where the smallpox is at the surface, and you put it to the eye, you can transfer the smallpox to your eye. That occurs in about 500 people for every million that get the vaccine. If you get "progressive vaccinia," your immune system is compromised. The virus just continues to grow and grow, and is often the cause of death.
No one is certain how many people will be hurt by the vaccine. A 1969 study found that, out of every one million people vaccinated, 74 will suffer serious complications, and at least one will die.
These side effects were never a secret, but they were rarely discussed, when the law required every child to get a smallpox vaccination before starting school.
Previous generations, Offit says, faced the disease regularly, and knew its power. "My parents, they saw diptheria. They saw polio. They saw the plagues that devastated children in this country. And so, the notion of getting vaccinated was, you know, nothing compared to what they were seeing during their normal day," he says.
If you did get the smallpox vaccine as a child, it may help you today. Some experts think you may still have some of your old immunity against the disease. But that's only a theory. There are no reliable studies on this, and other scientists disagree.
So why is the government recommending a dangerous vaccine that could kill people?
Because the disease it prevents is worse.
"It is the worst human disease. It probably killed more people in history than any other infectious agent, including the Black Death of the Middle Ages," says Richard Preston, who writes about deadly diseases like Ebola and anthrax. Nothing scares him like smallpox. He's just written a book called "The Demon in the Freezer," about how the smallpox virus has been turned into a weapon of mass-destruction.
"Smallpox as a weapon is the biological equivalent of the nuclear bomb. It is simply the most dangerous biological weapon in the world," he says. That's because it spreads on its own, unless you stop it.
Says Preston: "There is a heated debate going on in the scientific community right now about such things as, for each victim of smallpox, how many people are going to catch it from each victim? That's known as the multiplier of a virus. If the multiplier of smallpox is 10 - that is to say, if each person infected with smallpox on average gives it to another 10 people - then a smallpox outbreak would be explosive in our society."
The multiplier was much higher than 10 in a small town in Germany in 1970. One man was hospitalized with the disease, and kept in an isolation ward. But 19 hospital staff and patients, who never saw the man, got smallpox. Still, doctors were able to control that outbreak with what is known as "ring vaccination."
"We know how to put a ring around the infection to contain it. You identify a person who's infected, you quarantine them, you isolate their contacts, and then the contacts of those contacts. And that eliminated smallpox from the face of the earth," says Offit.
Offit thinks it's a mistake to vaccinate lots of people now, before there's any kind of outbreak. He thinks there's a safer approach: "Here's another way to do it. We can make the vaccine. Make sure we understand who's going to get it, who's going to be giving it. Then wait, wait for there to be one case of documented smallpox somewhere on the face of this earth and then we can move into vaccinating people, large numbers of people."
Many public health specialists who worry about vaccine side-effects say that only a few people should be vaccinated until there is an outbreak. But others are more fearful of a smallpox attack.
"You see very good physicians arguing very hard that smallpox is really not a problem, and that it can be easily handled. Those doctors are maintaining an excellent bedside manner with the American people, but they don't fully inspire confidence in me," says Preston.
Israel wants to be prepared for a smallpox attack. In August, they immunized nearly 15,000 health-care workers. More vaccinations are planned. So far, there have been four bad reactions, two very serious. And some health care workers are unwilling to be vaccinated.