To Vaccinate or Not to Vaccinate?

by Charles V. Peña, April 29, 2009

As this is written, the swine flu virus is believed to have infected more than 1,600 and killed more than 150 people in Mexico. In the United States, 64 cases of swine flu cases have been confirmed in California, Texas, Kansas, Ohio, and New York. Other countries with confirmed cases of swine flu are Canada, New Zealand, Spain, the United Kingdom, and Israel, with another 11 countries suspecting infections. The World Health Organization (WHO) raised its alert level from three to four on its six-level scale, meaning the agency believes the virus is capable of significant human-to-human transmission. Although not inevitable, there is a risk of a pandemic. Given the risk, the question is whether to vaccinate as a way to prevent the spread of swine flu so that it doesn’t reach pandemic proportions.

Swine flu is a contagious respiratory disease that usually affects pigs. The current strain is a mutation of the virus, which is a mix of human and animal versions. The virus spreads when an infected person coughs or sneezes around another person. People can also become infected by touching something with the flu virus on it and then touching their mouth, nose, or eyes. When the flu spreads person-to-person, instead of from animals to humans, it can continue to mutate, making it harder to treat or fight off because people have no natural immunity.

The U.S. Food and Drug Administration issued an emergency authorization that allows the distribution by a broader range of health care workers and loosens age limits (the median age of all the U.S. cases is 16 years) for the use of two of the most common anti-viral drugs, Tamiflu and Relenza, as a treatment response. But, so far, there is no mass vaccination program to inoculate people against the swine flu virus. One of the reasons is the 1976 response to an outbreak of swine flu at Fort Dix Army base in New Jersey that killed one soldier and infected hundreds more. Fearing an epidemic, then-president Gerald Ford ordered a nationwide vaccination program. The program was canceled after more than 30 people died (more than died from swine flu) after developing Guillain-Barré syndrome, a paralyzing nerve disease that can be caused by the vaccine. Fear of fatal side effects is reportedly why then-president George W. Bush decided in 2002 not to administer a nationwide smallpox vaccination program that could have resulted in dozens of deaths (the smallpox vaccine kills between 1 and 2 people per million people inoculated).

As a deadly contagious pathogen, the swine flu presents a Catch-22 for public officials. If they decide not to vaccinate (or wait too long to decide), then it could become a pandemic (in 1968, a Hong Kong flu pandemic killed about 1 million people worldwide, and in 1918, a Spanish flu pandemic killed as many as 100 million people). But if they jump the gun and impose mass vaccinations unnecessarily (as many believe was the case in 1976), then people at risk for the vaccine’s side effects may die needlessly.

Rather than choosing between a sit-and-wait approach or mandatory widespread vaccination, a better alternative would be voluntary vaccination – especially if there is no known effective treatment for a virus (as is the case with smallpox, for example). Of course, people would need to be made aware of the potential side effects and which population groups are most at risk for the side effects. But instead of the government forcing or preventing people from being vaccinated, individuals would make that decision for themselves based on their own assessment of the risks involved. Indeed, this is exactly how we treat seasonal influenza vaccination.

The benefit of such a policy would be that even if only a fraction of the population chose to be vaccinated, there would be a community immunity effect that would lower the rate of transmission of the disease in the event of an outbreak (or worse yet, a bioterrorism attack), as well as significantly increasing the effectiveness of post-infection vaccination and treatment. For example, recent research by British scientists found that if many people received a “pre-pandemic” vaccine ahead of time, many of the worst effects could be reduced if an outbreak did occur. Researchers found that people who had received a vaccine for bird flu (until recently considered the biggest threat for a pandemic) between seven and eight years ago still retained very good cell memories of how to fight the disease years later. Not only were they more resistant to the virus, but a simple booster update would be all that’s needed to protect them completely. In contrast, people who had not been vaccinated needed two doses to be protected from the virus.

The bad news is that the current swine flu is a different strain of the virus, and it is unclear whether currently available flu vaccines would offer any protection against it. According to British doctor Iain Stephenson at the Infectious Diseases Unit of the Leicester Royal Infirmary, it would take at least six months to develop a vaccine for this strain, test it for safety, send it to manufacturers for mass production, and then distribute it around the world. But voluntary vaccination with available vaccines might at least offer the prospect of some immunity from the swine flu rather than none at all, thereby helping to slow down the spread until a specific vaccine is developed.

Read more by Charles V. Peña