Mike the Mad Biologist

One of the thing we need to pay attention to during TEH SWINEY FLOO! is the role of bacterial infections in flu-related mortality: a fair number of the deaths ultimately could result from a secondary bacterial infection by organisms like Staphylococcus (including MRSA), Streptococcus, and some of the Gram-negative organisms. Unfortunately, this is happening in a significant fraction of cases:

Nevertheless, the 22 cases (among 77 deaths confirmed to be from H1N1) emphasize that bacterial co-infections are playing a role in the ongoing pandemic, something that was not clear at first, the CDC’s Dr. Matthew Moore said on the call.

“During the early part of this pandemic, evidence of bacterial co-infection was pretty much absent,” Moore said during the call, part of the CDC’s “Clinician Outreach and Communication Activity” program. That “may have led to the perception that bacterial co-infection is playing only a limited or maybe even no role in this current pandemic. . . . [But] bacterial pneumonia may be contributing to influenza-associated mortality in a manner similar to that in previous pandemics.”

The 77 patients whose deaths and autopsy data were evaluated by the CDC are expected to be described in a forthcoming article in the agency’s Morbidity and Mortality Weekly Report. They ranged in age from 2 months to 84 years, with a median age of 39. Nine out of 10 had some underlying condition that made them vulnerable to the severest effects of flu, such as obesity, cardiac disease, asthma, diabetes, or HIV infection. Three were women in the last trimester of pregnancy.

All appear to have been severely ill: 63% received influenza antivirals and 81% were put on ventilators. Pneumonia was diagnosed before death in 39% of the cases.

The 22 patients (29%) who were confirmed to have bacterial complications were infected with Streptococcus pneumoniae (pneumococcus), Staphylococcus aureus, Group A strep, and Haemophilus influenzae. (Four were infected with more than one bacterial type.) Five of the seven S aureus infections involved methicillin-resistant (MRSA) strains.

This is not unexpected, although the prevalence of MRSA won’t help. But this is the most disturbing part (italics mine):

Moore said the CDC is especially concerned that 16 of the 22 fall into categories of people who are recommended to receive pneumococcal vaccine because of their age or underlying chronic conditions. The agency received limited clinical data on the cases and thus could not say whether they received the vaccine–but it is well-known, Moore said, that only 16% of Americans who should receive pneumococcal vaccine do so.

In response, the CDC is urging people at high risk for pneumococcal disease to be vaccinated, Moore said: “If you add up all the people in the United States who should have received pneumococcal polysaccharide vaccine but have not yet received it, that totals 70 million individuals. We have a terrific opportunity here to prevent additional pneumococcal disease.”

We won’t be able to vaccinate everyone against swine flu in time, but we can vaccinate those at risk for pneumococcal disease. We don’t need to wait to make the vaccine until a certain season–this could have been done well before the swine flu outbreak*. Yet, once again, our vaccination non-policy is needlessly putting lives at risk.

We need to make the PCV7 (pneumococcal) vaccine part of our flu fighting strategy.

*Pneumococcal vaccine types not found in the vaccine are increasing in frequency (that whole natural selection thingee), so the vaccine will eventually have to be changed, but it won’t become obsolete every year as do the influenza vaccines.

Comments

  1. #1 jay
    September 30, 2009

    One should be careful about reading too much into “significant number of cases”. The sample size is so small such a result might be expected.

    Consider a hypothetical flu that had little mortality, then, when you selected deaths associated with it, you would expect that a significant number of those deaths were ‘helped’ by some other condition.

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