Blood transfusions and pandemic flu

As predicted, the pandemic of 2009 is beginning to yield more data, some of it directly applicable to pressing practical questions. The answers are still preliminary, and, as with all science, subject to revision. But it's what we have at the moment, and a letter that just appeared in the CDC sponsored journal Emerging Infectious Diseases, addresses an important question. During a flu outbreak, can hospitalized patients contract influenza from blood transfusions? Since people getting transfusions already have compromised health (else why would they be getting a transfusion?), they are at high risk for mortality with a supervening infection with influenza. No cases of transfusion-associated flu have been published, but there is evidence of a transient viremia (virus in the blood) with flu infections, so it is a real question.

Scientists in Japan, working with the Japanese Red Cross Blood Centers, intercepted blood products from donors where there was post donation suggestion of pandemic influenza virus infection and examined the blood for evidence of flu virus hemagglutinin or matrix gene RNA:

NAT was conducted by using 96 plasma and 67 erythrocyte samples obtained from 96 blood donors who had symptoms of influenza within 7 days postdonation. For 20 donors, pandemic (H1N1) 2009 was diagnosed within 1 day postdonation and, for another 20, within 2 days postdonation. Pandemic (H1N1) 2009 virus was not found in any of the samples tested, but it was consistently detected in the external positive control. These results suggest that the viremia with pandemic (H1N1) 2009 virus, if any, is very low and can be missed by current NAT or that the viremic period is too brief to identify viremia. Although the risk for transmission of pandemic influenza by transfusion seems to be low, further investigation is needed to elucidate this risk. (Matsumoto C, Sobata R, Uchida S, Hidaka T, Momose S, Hino S, et al. Risk for transmission of pandemic (H1N1) 2009 virus by blood transfusion [letter]. Emerg Infect Dis. 2010 Apr; [Epub ahead of print, DOI: 10.3201/eid1604.091795], figure omitted)

In other words, no evidence of influenza viral material was detected in donated blood from people who shortly after giving it came down with flu. This is reassuring, although perhaps not surprising, since transmission of flu by blood has not been reported. But it's nice to know that even when you look hard for the virus, you don't find it. Since during flu season a lot of people get flu and a lot of people donate blood and a lot people get transfused with that blood, it's a piece of good, although provisional news.

I'll take what I can get.

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Unrelated to this, I see that there's a peer-reviewed writeup of one of the events you mentioned here a couple of years ago, the workers at the slaughterhouse who developed CNS symptoms.

Holzbauer SM, DeVries AS, Sejvar JJ, Lees CH, Adjemian J, et al. (2010) Epidemiologic Investigation of Immune-Mediated Polyradiculoneuropathy among Abattoir Workers Exposed to Porcine Brain. PLoS ONE 5(3): e9782. doi:10.1371/journal.pone.0009782

@2. How far in advance? We know that older blood causes more side effects, that the hemoglobin degrades and has lower oxygen-carrying capacity. I would always agree it's better to have sufficient stocks on hand, but I don't think the answer is to stock-pile it months ahead, particularly if the evidence is that flu is not transmitted through transfusions.

Provide free flu shots early for regular doners as a thankyou whether they fit any risk catagory or not?

Seems like a good carrot with the fringe benefit of making the blood supply even safer.

Even if it was detected, would it matter? Is there any reason to think it could infect the recipient? There is no nucleus so the virus shouldn't be able to make new proteins for replication.

Locasta: If intact and replicable virus isn't there or is there in such low levels the risk is tiny then that's one thing (what we apparently have). if it's there, then it may or may not be able to infect host cells in the recipient. Remember, the virus is not replicating in the aerosol droplets in a sneeze or cough, either. But if an intact virus can find a host cell then it might be able to replicate. We don't know much about transmission so this is an interesting piece of the puzzle. We'll all have to stay tuned. But looking was the right thing to do.