February 22, 2003
Smallpox Vaccine Risks Put Into Perspective

Jonathan Rauch puts the risk of smallpox vaccination into perspective by comparing it to car driving risks.

But the risk of a potentially life-threatening reaction to the smallpox vaccine is between 14 and 52 per million inoculations, according to the Department of Health and Human Services, and the odds of death are one to two per million. By comparison, the chance of dying behind the wheel of a car is about 24 per million drivers per year. In other words, the fatality risk you would assume by taking the smallpox vaccine is about a 10th the risk you assume by driving around, and the reason for being vaccinated seems somewhat more compelling than, say, the need for a Slurpee.

A more complex breakdown of smallpox vaccination risks puts the risk of death from smallpox vaccination at 5 per million for babies under the age of 1 but a tenth that amount after the age of 1. Though there is not enough data to determine the risks for those after age 20.

There is a risk after vaccination of passing vaccinia on to someone who has a compromised immune system. A car driver has a 100 times greater risk of killing a pedestrian or other nonrider than to kill someone with "contact vaccinia" after getting vaccinated.

Working from data that Neff and three of his colleagues recently published in the Journal of the American Medical Association, I figure the odds of dying from "contact vaccinia," as it's called, at two to four per 10 million inoculations. In 2001, by way of comparison, every 10 million licensed drivers caused the deaths of about 300 pedestrians and other nonriders -- people who had not voluntarily assumed the risk of getting into an automobile.

There has been a lot of debate about whether getting vaccinated for smallpox is worth it. The problem with the debate is that we can't know what the Iraqi and North Korean regimes and other potential possessors of smallpox are capable of. We do not know with certainty the identity of every government that has smallpox or how well guarded their smallpox stock is. Therefore we are stuck comparing a precisely calculable and known risk of vaccination with an alternative which has risk probabilities that are not known.

Having already been inoculated for smallpox once and having emerged unscathed I'd be inclined to get inoculated again if the opportunity to do so was made available to the general public. I have a rather pessimistic view of what terrorists and nasty regimes are capable of.

It is possible to develop a safer form of smallpox vaccine using DNA vaccines. DNA vaccines can cause the body to make protein antibodies while at the same time the inability of the DNA vaccines to replicate eliminates the risk from infection. The problem with such an alternative vaccine is that it would take years to develop and so would be of no help in reducing the threat of vaccination or bioterrorist attack in the short term.

DNA vaccines have an additional benefit: They can be much more rapidly modified to deal with bioengineered weaponized versions of pathogens that are immunologically different fom naturally occurring versions of pathogens. The US Navy's Naval Medical Research Center has been working on DNA vaccines.

Building on the innovative DNA vaccine models developed by Carucci and his fellow Navy researchers, the three captains and their colleagues have quietly worked in laboratories at NMRC to develop the next generation of vaccines against deadly diseases, whether they are naturally occurring or bio-engineered weapons.

Traditional vaccines have saved countless millions, but have their limitations. They take years to develop and can be difficult and costly to manufacture. They need constant refrigeration, and generally cannot be mixed to inoculate against more than one disease at a time. And there's always the danger of side effects.

But now, Carucci, Mateczun, Galloway and their colleagues may have taken the first steps to a potential new generation of vaccines, which is expected to be safer, cheaper, stable, have fewer side effects, be more effective against a wider variety of diseases and easier to administer.

They are expected to have what the researchers call "agility" -- that is, they can be retailored quickly to become "just-in-time" inoculations against bacteria, viruses or other pathogens that have emerged or re-engineered to make existing vaccines ineffective.

"One of the potential advantages of this agile vaccine technology, which the Navy is a leader in developing, is that production from start to finish might take a matter of months, not years," said Rear Adm. Steven Hart, MC, head of the Navy's medical research programs.

Even months is still too long a time. What the US and other Western nations need is the ability to sequence a new version of a pathogen and manufacture a new version of a DNA vaccine in a matter of days.

Share |      Randall Parker, 2003 February 22 08:36 PM  Dangers Tech General


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