Flu antibodies can make disease worse

Some antibodies to flu viruses may actually make patients sicker, a new study of pigs suggests.

The finding, published August 28 in Science Translational Medicine, may point to problems with catchall influenza vaccines.

Pigs vaccinated against a seasonal strain of influenza made antibodies to that strain. Some of the antibodies could also latch on to a different flu virus that caused a pandemic among humans in 2009, report scientists led by Hana Golding of the Food and Drug Administration’s Center for Biologics Evaluation and Research in Bethesda, Md., and Amy Vincent of the Department of Agriculture’s National Animal Disease Center in Ames, Iowa.

Instead of protecting the pigs against the 2009 pandemic flu, the broad-range antibodies actually helped the virus invade lung cells, causing pneumonia and lung damage.

Scientists hoping to create a universal flu vaccine need to learn how the pigs’ antibodies and viruses interacted to make the disease worse, James Crowe Jr. of Vanderbilt University writes in a commentary in the same issue of the journal.

And vaccines aren't the only problem, Crowe says. Natural infections may provoke similar disease-worsening problems.