Monday, September 14, 2009

Cautious optimism regarding recent tests of swine flu vaccine

From Scott McPherson's Web Presence

Posted on Friday, September 11, 2009 at 03:24PM by Registered CommenterScott McPherson in Politics and government, influenza and infectious diseases | Comments1 Comment

The newspapers are positively aglow with the recent studies which seem to indicate the H1N1/2009, (aka swine flu) vaccine can confer immunity with one shot, and after only ten days. And justifiably so! For the news is good.

Previously, scientists and researchers postulated that it would take two jabs, spaced three weeks apart, in order to deliver enough attenuated inert virus to confer immunity to swine flu.

So this study, on the surface, is decidedly good news. The ramifications of this are nothing short of spectacular. First, it means the entire seed virus-to-vaccine chain performed surprisingly well and was also surprisingly nimble. As you recall, initial seed virus stock was very slow to grow, and the CDC and WHO had to whip up a faster-growing batch of seed virus stock to send to vaccine manufacturers.

Second, there had to be enough eggs, and those eggs had to be free of cross-contamination. So as Earl Butz, late of this earth and the Ford Administration famously said, the roosters of America did their duty.

It also means very little virus "drifted" during manufacturing, and it speaks volumes about the research and quality control that the vaccine industry has undertaken since the debacle of 2004-05's flu season. For more information and a superb primer on vaccine manufacture, read the book "A Warning Shot: Influenza and the 2004 Flu Vaccine,"by Timothy Brookes and the staff at Johns Hopkins.

The US government ordered 195 million doses of the new H1N1/2009 monovalent vaccine. The calculus performed was that most Americans would need two jabs, as I said earlier. Now if these initial test results hold firm, it means we will now have double the available vaccine than we thought we had a month ago.

The projected available vaccine doses equals 62% of the American population. I dare say that if we were to vaccinate everyone in the high-risk groups, plus virtually all school-age children under 25, we stand a very good chance of reaching the Holy Grail of Herd Immunity. Herd Immunity is when enough people are vaccinated against a virus, that virus can no longer gain a beachhead in a community. It fails to achieve the critical mass necessary to sustain human-to-human transmission. Herd Immunity means the virus cannot infect enough hosts in a chain, and the chain breaks. Think a viral chain mail/email scheme that breaks due to unwilling participants.

Same thing: The virus' chain of transmission is broken when enough people are vaccinated, predominantly the young. It is the young -- schoolchildren and college students -- who pass this virus (and all flus) on to their family members and then on to the community at large. You break that chain, you break the pandemic.

So the Quest for Herd Immunity against a pandemic virus is within the reach of Americans. It decidedly does not mean the same for persons within developing nations, however. And I would not be the least bit surprised if persons such as Supari of Indonesia and others begin clamoring for vaccines, since everyone thought it would take two jabs anyway. It might be appropriate for the favored nations to siphon off some of their vaccine to the WHO for use in developing nations.

Even if we were to siphon off some vaccine, the goal of herd immunity against H1N1/2009 could be within reach. Let us hope that the final test reports confirm the initial speculation. We could use some good news now!

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