Friday, October 23, 2009

H1N1 vaccination, anyone?

So Singapore gets her H1N1 vaccine fix in a couple of week's time. I think the MOH had spent about S$10-20 million to the one million shots for us so we should grateful for the preparedness. Word out is that most of these are the Australian CSL Panvax vaccines, and about a third might be the GSK version, Pandemrix. But no idea how these gets distributed so you might want to ask when you do go for your shots. Pandemrix is the one with the AS03 adjuvant.

A couple of things bother me though. There's been a lot of talk about a second wave emerging. The reason for the vaccinations are to mitigate against this second wave. But I never quite bought into this second wave thing for Singapore. If indeed there is a second wave, given there will be more herd immunity, it would be a lesser wave than the first, would it not? Unless of course, the virus mutates. But it hasn't as yet, and it looks like we are dealing with the same, not so virulent, not so lethal , not so pandemic virus.

Also seasonal flu? That applies to temperate countries with summer/winter type seasons. Since the only winter we have in Singapore is the styrofoam/soap variety in Orchard Road, there isn't going to be much in terms of seasonal change in flu transmission. In fact, a scan of the MOH epidemiological stats over 2004-2008 confirm that the incidence of acute respiratory infections were pretty flat throughout each year. The only interruption to this flatness was the rather short-lived H1N1 pandemic earlier this year. So the only seasonal change we may expect in H1N1 would be due to increased seeding by travelers from temperate zones who carry the virus to us. And given the increased herd immunity, such seeds may not transmit that well.

Actually, I wonder why the MOH does not survey the level of herd immunity in our population beefore embarking on any immunization programmes? This developing herd immunity would certainly be one of the reasons why the earlier first wave pandemic fizzled out. After representing more than 60% of samples at the peak fo the pandemic, it is now hovering at about 24% of cases surveyed.

So is there a rush to get vaccination? Apparently not if the health care workers are polled. But these are still early days.

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