Wednesday, June 22, 2005

Influenza B outbreak in New Zealand

As some of you may have heard already, there is a current outbreak of influenza strain B, which was responsible for the epidemic in Hong Kong (1968) here in New Zealand in the North Island. Several children have already died and numerous students have been kept home from school. Thankfully, it doesn't appear that the epidemic has spread to the South Island and the upcoming school holidays will (with some luck) curb any further transmission of the virus.

Aside from being an unfortunate event, this epidemic is a reminder that viruses are not always completely absent just because the diseases they cause aren't around. It is likely that the resurgence of this virus is due to waning immunity from people born well after the original strain was circulating (hence the effects being seen among school children). Normally the virus is added to the current flu vaccine, but this year in an almost ironic twist the World Health Organisation decided to remove that particular strain from the vaccine. It is unlikely that this would have initially been any good at stopping the epidemic from starting, because the flu vaccine is generally only recommended to those at risk and the elderly (most school kids wouldn't be getting it) but it would have helped after it began.

This is yet another reminder that even viruses that we think are well under control can and will come back when immunity to them drops. This is why, even though diseases such as rubella, and measels aren't anywhere near as prevalent it is still important to keep vaccinations for them.