Flu vaccine may make asthma worse

The flu vaccine can cause pulmonary complications and exacerbate asthma, according to new research.

In the double blind, placebo controlled study, carried out by researchers at medical hospitals in England, roughly one in 12 patients (8 per cent) experienced a trigger of asthma from the flu vaccine.

More than 250 patients aged 18-75 years who reported respiratory symptoms and hospital admissions were studied for two weeks before the first flu injection and until two weeks after the second injection.

The vaccine and placebo were administered randomly, and there was a two week interval between injections.

Results show that among 255 participants, 19 recorded an exacerbation within 72 hours of the flu vaccine, compared with only three after placebo.

Despite these findings, the researchers claim that the risk of pulmonary function abnormalities is very small and outweighed by the benefits of vaccination (The Lancet, 1998, 351: 326-31).