H1N! Swine Flu Devastating South America

A passenger takes precautions at Ezeiza International Airport, Argentina, as the swine flu pandemic intensifies (Image: Daniel Garcia / AFP / Getty Images)

THE swine flu pandemic is intensifying in South America and finding little resistance. The US White House will meet with state representatives on 9 July to discuss preparations for the autumn flu season in the US. The UK has shifted its response from protection, to dealing with the impact of widespread infection in the UK.

Meanwhile, in South America, in the midst of its winter flu season, swine H1N1 virus seems to be replacing the seasonal flu viruses that circulated till now, a classic pandemic behaviour. This raises further concerns that seasonal flu vaccine, which some companies are still making, may be useless when the northern hemisphere's flu season arrives later this year.

In the flu pandemics of 1918, 1957 and 1968, the pandemic virus completely replaced the circulating seasonal flu but in 1977, an accidentally released mild H1N1 virus simply circulated alongside the existing flu, H3N2. So, no one is sure how this swine flu H1N1 will behave. It is overwhelming what is not known about this influenza and its potential devastating impact on the civilised world.

If it does not replace the seasonal viruses - the milder H1N1 and the H3N2 - the world faces the prospect of being infected by all three viruses at once. This would be a very complicated and dangerous scenario: both seasonal and pandemic vaccines would be needed and differing age groups of people would be affected. Let's hope that what is happening in South America, is not indicative of this influenza's emerging profile.

In North America, swine flu also dominates: as expected, more than 98 per cent of flu cases genotyped in the US in late June were caused by the pandemic virus. While seasonal flu viruses normally die out in the summer, the pandemic virus has the advantage that few people have any immunity to it.