Emerg Infect Dis. Serologic Survey of Pandemic (H1N1) 2009 Virus, Guangxi Province, China

[Giuseppe]

Serologic Survey of Pandemic (H1N1) 2009 Virus, Guangxi Province, China (Emerg Infect Dis., extract, edited)

[Source Full Document: LINK. EDITED.]

DOI: 10.3201/eid1511.090868

Suggested citation for this article: Chen H, Wang Y, Liu W, Zhang J, Dong B, Fan X, et al. Serologic survey of pandemic (H1N1) 2009 virus, Guangxi Province, China [letter]. Emerg Infect Dis. 2009 Nov; [Epub ahead of print]

Serologic Survey of Pandemic (H1N1) 2009 Virus, Guangxi Province, China


To the Editor:

Since mid-April 2009, a new influenza A virus (H1N1), now called pandemic (H1N1) 2009 virus, has caused influenza outbreaks in humans in North America (1) and a worldwide pandemic (2?4). Human pandemics occur when a new virus subtype emerges that is capable of human-to-human transmission in a population with little or no neutralizing antibodies to the new virus (4).

The current outbreak presents the first opportunity to directly observe this process. We used hemagglutination inhibition (HI) and virus neutralization (VN) assays to detect antibodies in 4,043 serum samples from residents (7?84 years of age) of 2 counties in Guangxi Province, People?s Republic of China, collected during July?August 2008. These persons were mostly farmers who lived in rural areas. Serum samples were obtained, transported, and frozen at −80?C as described (5). No participants had a history of vaccination against seasonal influenza. Antibodies were also detected in another 22 persons (<40 years of age) in Shantou, Guangdong Province, who had received 3 vaccinations for seasonal influenza since 2006.

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[Vibrant62]

Re: Emerg Infect Dis. Serologic Survey of Pandemic (H1N1) 2009 Virus, Guangxi Province, China

EXERPT
Our results suggest that most persons in our study population from Guangxi, China, are seronegative for pandemic (H1N1) 2009 virus (1). Serum samples from only 0.3&#37; of persons tested neutralized the novel CA/04 strain. This finding contrasts with findings from the United States that serum samples from ≈11% of unvaccinated persons had antibodies against CA04 (7). Furthermore, all CA04-positive persons in our study were <60 years of age; the US study reported a 33% seropositive rate for this age group.
These differences may have been caused by the high proportion of seasonal influenza vaccination coverage in the United States when compared with results form our unvaccinated population from southern China. Therefore, we suggest that vaccination against seasonal influenza, rather than exposure to older, seasonal, influenza viruses (H1N1), which may be
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genetically and antigentically similar to pandemic (H1N1) 2009 virus, as suggested (7), might have generated partial protection against this new virus. No persons in our vaccinated control group had neutralizing antibodies against CA04.
We hypothesize that the absence of neutralizing antibodies in our control group, all of whom had been vaccinated 3 times, suggests that prolonged and repeated vaccination is required for partial immunity to CA04 or that older vaccines may confer some degree of protection. If these serologic differences are indicative of increased susceptibility, we would expect higher infection attack rates in largely unvaccinated populations than in vaccinated populations in countries such as China.

[AlaskaDenise]

Re: Emerg Infect Dis. Serologic Survey of Pandemic (H1N1) 2009 Virus, Guangxi Province, China

Therefore, we suggest that vaccination against seasonal influenza, rather than exposure to older, seasonal, influenza viruses (H1N1), which may be genetically and antigentically similar to pandemic (H1N1) 2009 virus, as suggested (7), might have generated partial protection against this new virus.

It's great to see a conclusion about causes that was not based on assumptions.

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[Laidback Al]

Re: Emerg Infect Dis. Serologic Survey of Pandemic (H1N1) 2009 Virus, Guangxi Province, China

Here is another study that contradicts the unpublished Canadian study that seasonal flu vaccinations increase the risk of novel H1N1 infection.