Flu Scan for Aug 02, 2016

2009 H1N1 flu and obesity
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Adjuvanted flu vaccine in obese mice

Study finds obesity not linked to ILI at end of 2009 H1N1 pandemic

A number of studies conducted at the time of the 2009 H1N1 pandemic and shortly afterward reported a higher risk of severe disease in obese patients, while some did not. Today a study in Influenza and Other Respiratory Viruses found that obesity was not a risk factor for the more general condition called influenza-like illness (ILI).

UK investigators analyzed data from 8,407 people (6,984) who participated in the Health Survey for England for 2010. They found that 12.8% of obese people reported ILI, compared with 11.8% of those who weren't obese. Adjusted odds ratios were 1.16 for obese adults and 1.26 for obese kids, neither of which was statistically significant.

The authors noted, "Further studies using active prospective ILI surveillance combined with laboratory reporting would reduce bias and improve accuracy of outcome measurements."
Aug 2 Influenza Other Respir Viruses abstract

 

Obese mice not protected from adjuvanted flu vaccine, researchers note

Obese mice not only had a weaker immune response to adjuvanted flu vaccines, they also were not protected from an influenza challenge, according to an mBio study today led by researchers with St. Jude Children's Research Hospital in Memphis, Tenn.

The team of scientists used an inactivated vaccine with both the H1N1 strain and H7N9 avian flu, which may have pandemic potential. They varied the dose and used different adjuvants, which are substances that boost the immune response, in both lean and obese mice.

While adjuvants improved the immune response in both lean and obese mice, the overall immune response was reduced in the obese rodents compared with the lean ones. The obese mice had lower antibody levels, including lower levels of neutralizing antibodies, and higher virus levels, in their blood. What's more, lean mice who received vaccines with adjuvants were protected from severe flu infections, whereas obese mice were not.

Protective antibodies from lean mice also failed to protect the obese mice from influenza. "That suggests the problem lies with the immune response of the obese animals rather than the antibodies themselves," said first author Erik Karlsson, PhD, of St. Jude's, in a hospital news release.

"The virus penetrates more deeply into the lungs of obese mice, and the animals seem to have a more difficult time repairing the damage," said corresponding author Stacey Schultz-Cherry, PhD, also of St. Jude's.
Aug 2 mBio study
Aug 2 St. Jude's news release

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