H1N1 Vaccine as Safe as Seasonal Vaccine, WHO Says

Emma Hitt, PhD

November 19, 2009

November 19, 2009 — The H1N1 2009 pandemic influenza vaccine appears to be as safe as the seasonal flu vaccine, according to the World Health Organization (WHO).

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.

At least 80 million doses of vaccines have been distributed and 65 million doses have been administered. "These are figures that we have received from 16 countries, but we think they are conservative estimates because immunization campaigns are under way now in 40 countries," Dr. Kieny added.

The WHO expects to start shipment of the vaccine to developing countries at the end of this month. According to Dr. Kieny, this represents a slight delay, but they expect that all vaccine doses will reach 95 eligible countries during the next 3 months.


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