Canada Probes H1N1 Vaccine Anaphylaxis Spike

MedpageToday

Canadian health officials are continuing to investigate a spike in anaphylaxis associated with one batch of the country's H1N1 vaccine, made by GlaxoSmithKline.

Overall, the rate of anaphylaxis associated with the 15 million doses of the vaccine that have been shipped so far is 0.32 per 100,000 doses given, a Canadian health official told reporters late last week.

But six cases are associated with lot A80CA007A, which contained 172,000 doses of the adjuvanted Arepanrix vaccine, according to David Butler-Jones, MD, Canada's chief public health officer.

All but about 15,000 doses of the lot had been used, so that the anaphylaxis rate was about four per 100,000 -- markedly higher than the overall rate, Butler-Jones said.

All six patients recovered fully.

The spike in cases may be a result of chance, but the remaining doses are not being given while the investigators look into the issue.

Butler-Jones said there were no obvious glitches in the manufacturing process, but what investigators are "looking at is whether or not there was something else, whether it was something to do with when it was shipped."

The issue "gives us cause to wonder whether there's something wrong, or it may just be the odds," he said. He added that the reactions do not appear to be related to the adjuvant used in the vaccine.

Since the vaccine program has been under way in Canada, Butler-Jones said, there have been 24 confirmed anaphylactic reactions, including one in which the patient died.

Butler-Jones said the man -- reported to be in his 80s -- met the criteria for an anaphylactic reaction, but it remains unclear whether that was the cause of death.

U.S. officials, meanwhile, said last week they have not seen anything unusual with their vaccines, with most reported reactions being local pain and redness. (See Bacterial Disease Linked to H1N1 Flu Worries CDC)

Anne Schuchat, MD, director of the CDC's National Center for Immunization and Respiratory Diseases, said severe allergic reactions "are not showing up more commonly than we would expect."