Is the H1N1 Vaccine Safe?

Is the H1N1 vaccine safe? I've heard this question a lot since I began promoting the book I co-authored, The Complete Idiot's Guide to Vaccinations. Young adults and mothers of young children tend to ask me about the H1N1 vaccine, because they are weighing the risks and benefits of getting vaccinated.

Modern vaccines are extremely safe. Problems such as bacterial contamination of vaccines, a serious threat several generations ago, has been largely eliminated through the use of preservatives and improved packaging. Many older vaccines have also been reformulated to reduce the risk of side effects (such as the old DTP vaccine, and the earlier rotavirus vaccine for children).

The H1N1 vaccine is made in the same way as the seasonal flu vaccine. The viruses that cause the flu are grown and biologically weakened in chicken cells, until they are still strong enough to create an immune system response in people, but too weak to cause the disease in a healthy person. Then the weakened viruses are either:

• killed and used in the seasonal or H1N1 flu shot (the best choice for people with weakened immune systems or other risks), or 
• kept alive and used in the seasonal or H1N1 flu nasal spray vaccine (the best choice for certain people with healthy immune systems).

The seasonal flu shot has been available since the middle of the last century; the nasal spray flu vaccine was licensed in the United States in 2003.

The CDC tracks health problems that might be linked to vaccines with the Vaccine Adverse Event Reporting System (VAERS). Both health care providers and the general public can report health problems that occurred after a vaccination to VAERS. Researchers monitor VAERS, looking for patterns of problems with a vaccine. If a pattern does occur, then they do further research within the Vaccine Safety Datalink (VSD), a database containing the health records from eight managed-care organizations across the country.

What have they found since they have been tracking the H1N1 flu vaccine? The CDC's Dec 11 Morbidity and Mortality Weekly Report (MMWR) found that the risk of serious side effects (adverse events) from the H1N1 vaccine is about the same as the risk for the seasonal vaccine. In a word: low. From October through November 2009, VAERS data showed 82 adverse events per million doses of H1N1, and 47 adverse events per million doses of seasonal flu vaccine.

Still, the rumors are flying about the H1N1 vaccine: that it can cause Gulf War Syndrome or Guillain-Barre syndrome, that it contains Agent Orange, and so on. The website FactCheck.org's "Inoculation Misinformation" article provides a good overview and rebuttal of some of the questions that have cropped up in emails and online about the H1N1 vaccine.

Gender and Cancer Vaccines

A number of cancer vaccines are on the market or under investigation right now, many targeted to gender-specific cancers. Along with the FDA-approved Gardasil(TM) HPV vaccine, which can prevent certain types of cervical cancer, trials are underway on the prostate cancer vaccine GVAX(R), a breast cancer vaccine, and another cervical cancer vaccine.

One important difference between all these vaccines is that Gardasil is given before any cancer diagnosis, and the other vaccines under trial that I mentioned are given after a cancer diagnosis in addition to standard cancer treatment. These post-diagnosis vaccines seem to be the trend with cancer vaccines, despite the heavy marketing of Gardasil. These vaccines are designed to "retrain" the patient's immune system to respond more effectively to proteins associated with cancer cells. Some of these vaccines are developed using the patient's own cells, and other are not.

Two promising post-diagnosis vaccines under investigation that are not gender-specific target lung cancer (the most deadly cancer among both men and women) and cutaneous melanoma (which is more deadly among men than among women).

I'm curious about the gender differences between cancer vaccines. Do women respond more favorably than men to cancer vaccines, or vice versa? Are vaccines that use the patient's own cells more or less effective than those that don't? Are vaccines for gender-specific cancers, such as prostate and cervical cancer, more or less effective than vaccines for cancers that can strike both genders? There might be no patterns here, but if there are, it would be interesting to see how physiology, sociology, and other factors impact the effectiveness of these vaccines.