World health body says H1N1 vaccines safe, effective

One dose of swine flu vaccine is sufficient to induce an immune response in people aged six months and older, and pregnant women can safely be immunized with either of the licensed swine flu vaccines, the World Health Organization said Friday.

The highest-level advisory body to WHO on immunization and vaccination policy, an advisory body comprised of experts from around the world, has reviewed the results of clinical trials involving several thousand people and more than several hundred thousand who have been vaccinated in "real field" operations organized by 14 countries.

"All the reports received today following vaccination either in clinical trial or live vaccination campaign have showed the safety profile of these pandemic vaccines is good and is very similar to the ones for seasonal influenza," Dr. Marie-Paule Kieny, director of WHO's Initiative for Vaccine Research told reporters during a briefing Friday.

"Nothing in terms of adverse events has been noted," Kieny said.

Given the significantly higher risk of severe complications in pregnant women who get infected with H1N1, especially in their second and third trimester of pregnancy, "these women can be vaccinated with any of the currently licensed vaccines," Kieny said.

"All the reports received today following vaccination either in clinical trial or live vaccination campaign have showed the safety profile of these pandemic vaccines is good and is very similar to the ones for seasonal influenza vaccines," she said.

Early in the outbreak, WHO's vaccine advisory panel had recommended pregnant women receive an unadjuvanted vaccine if one was available.

An adjuvant is a compound added to a vaccine to boost the immune response to the shots. That recommendation led Canada to order 1.8 million doses of unadjuvanted vaccine for pregnant women — a regulatory decision that has now led to vaccine delays that threaten to compromise the rollout of the largest immunization program in Canada's history.

The federal government said it was informed by Canada's H1N1 vaccine manufacturer, GlaxoSmithKline, that vaccine supply will be lower next week because its facility only has one production line for two types of vaccine.

GSK first produced batches of vaccine with an adjuvant, and by the end of the day Friday, six million doses will have been shipped to the provinces and territories. It temporarily switched its production line to manufacture 1.8 million doses of vaccine without the adjuvant, the vaccine that is preferred for pregnant women. It has now switched back to making the adjuvanted vaccine but because of the interruption caused by making the unadjuvanted vaccine, there is reduced number of doses for next week.

But Kieny says that, after reviewing the evidence, the expert advisory panel concluded "there is no reason to favour one vaccine over the other, in particular for pregnant women.

Canada has recommended two half-doses of adjuvanted vaccine for children. But Kieny said all the vaccines induce a "significant" response in children after one dose.

In countries where children age six months to 10 years old are on the priority list for receiving vaccines, the priority should be to give them at least one dose of the vaccine to cover as many as possible.

The WHO panel also said both the seasonal flu shot and H1N1 vaccine can be given at the same time.