# 4074
It comes as no surprise that a certain percentage of people who are exposed to the pandemic flu virus go on to develop antibodies without experiencing clinical symptoms.
With seasonal flu, it is expected that anywhere from 1/3rd to 1/2 of people exposed, never fall ill.
But when a new virus appears, until serology tests can be conducted, we don’t have a good handle on what percentage might remain asymptomatic.
Earlier this months I reported on New Zealand’s plans to test the blood of 2,500 people (see New Zealand To Conduct Seroprevalence Studies) to try to determine the actual rate of infection over the summer. Other countries are doing so, as well.
Today we learn of a relatively small study, conducted in the UK, of school aged children to determine how many have elevated antibody titers to the novel H1N1 virus.
The results are encouraging, in that a substantial percentage (about 1/3rd) of the children tested show antibodies to the virus, while only about 1 in 10 reported flu symptoms.
This report from the BBC.
More children 'than expected have had swine flu'
By Nick Triggle
Health reporter, BBC NewsUp to a third of children in some areas may have had swine flu, but many will not have been ill, analysis shows.
The Health Protection Agency has reviewed blood tests which showed higher levels of infection among children than originally thought.
In hotspot areas, such as London and the West Midlands, a third of school-aged children may have had the virus, but only one in 10 or less got ill.
Across the UK, the figure is probably about a fifth, the HPA said.
The findings reinforce the fact the pandemic is a mild strain of flu.
Flu, whether it is seasonal or swine, always affects more people than actually get ill.
The ratio is normally about 50-50 and pandemic flu is probably not much different, the HPA said.
Fergus Walsh, medical correspondent for the BBC, who writes the Fergus on Flu blog, has more at:
Up to a third of children in some areas have been infected
Fergus Walsh | 16:54 UK time, Tuesday, 24 November 2009
