By now, everyone in Beijing is either: 1. recovered from having H1N1; 2. tired of hearing about H1N1; or 3. recovered and tired of hearing about it. But one common theme in discussions remains the uncertainty around the vaccine. Well, finally, there is a lot of real data last week that I wanted to share with you: hard numbers on safety that hopefully will raise up future debates with more facts.

The Data on H1N1 Vaccine Safety

First is a WHO statement that the H1N1 vaccine is as safe as seasonal flu vaccine. This was presumed all along, but now there is data supporting it. Straight from the source:

About 1 adverse event is being reported for every 10,000 doses, said Dr. Marie-Paule Kieny, director of the WHO’s Initiative for Vaccine Research, at a virtual press briefing today. Of those adverse event reports, about 5 of 100 are considered serious.

According to Dr. Kieny, serious adverse events so far include 30 deaths and about 12 cases of Guillain-Barré syndrome; however, she emphasized that none of the deaths reported to date has been confirmed as being caused by the vaccine. In addition, all cases of Guillain-Barré syndrome have been transient, and only a few have been linked to the vaccine.

Dr. Kieny added that there appears to be no difference between the safety profile of the seasonal and pandemic influenza vaccines, and the number of adverse events is comparable between the 2 vaccines. In addition, the safety profiles of the different forms of pandemic vaccine are also similar.

Adverse reactions associated with the pandemic vaccine include a variety of local reactions including “pain at injection site, swelling, redness, and reactions such as fever, headache, muscle pain, or fatigue,” Dr. Kieny said. “These generally resolve within 1 or 2 days.”

“No new safety issues have been identified from reports received to date,” she said.

About 80 million doses have already been given worldwide. There is also more scholarly discussion in Medscape’s article, No Adverse Events Reported So Far With H1N1 Influenza Vaccine

The Data on H1N1 Illnesses

The US CDC last week had an excellent review of all reported cases of H1N1 virus since last April. One interesting finding:

The results of this method confirm previous epidemiological data indicating that this disease primarily affects people younger than 65 year old, with the number of cases, hospitalizations and deaths overwhelmingly occurring in people 64 years and younger. This is very different from seasonal influenza, where about 60 percent of seasonal flu-related hospitalizations and 90 percent of flu-related deaths occur in people 65 years and older. The proportion of younger people being impacted by 2009 H1N1 is much greater than what occurs during seasonal flu and people 65 and older are much less affected by this virus than what routinely occurs with seasonal influenza. The results generated by this method also underscore the continued importance of the 2009 H1N1 vaccination program and support the recommended target groups for vaccination.

The Bottom Line?

Well, at least now we have hard data on whether or not the vaccine is safe, and those of you still uncertain simply have to look at the new data and find reassurance.

But — and this is important — the overall picture is that the H1N1 virus is not proving to be dangerous to many people, and the overall fatality rate seems to be quite low. This is great news, of course. Unfortunately, there is already grumbling that public health people have overreacted. But if I may remind everyone that it’s the mission statement of the WHO and public health people to look out for people’s health, and that means avoiding worst-case scenarios like the 1918 H1N1 influenza pandemic, which killed far more people than died in World War One. The whole point of vaccination is to prevent such another catastrophe; and public griping about overreaction is music to WHO’s ears compared to public griping about not doing enough. That means they’ve done their job and saved lives.