CHARLOTTESVILLE, VA — America could be in for a severe influenza season, in which flu vaccines offer limited protection, a UVA Health flu expert is warning.

Frederick G. Hayden, M.D., a professor emeritus at the University of Virginia School of Medicine, said that the available vaccines appear to be a poor match for the subclade K virus that has already started circulating in the United States. The virus likely will gain traction over the holidays and spread further when schools reopen after winter break, Hayden said.

The variant is of the same influenza A lineage that caused the flu pandemic of 1968, killing an estimated 100,000 Americans and a million people worldwide. The strain, H3N2, has circulated since and often sparks severe epidemics that are more likely to cause deaths and hospitalizations than other strains, especially among the elderly and very young.  

“However, available vaccines will reduce the risk of serious illness and potentially the spread of this virus,” Hayden said. 

Hayden raises his concerns about the upcoming flu-season in a new article in the Journal of the American Medical Association co-authored by British virologist Maria Zambon, Ph.D.  

Of particular concern, the scientists say, is the mismatch of the virus and the available vaccines. Vaccine makers must prepare their vaccines well before flu season, so that public health agencies like the CDC and WHO can make educated guesses about which strains to include. In the UK, an early analysis suggested that injected vaccines for adults were only 32 percent to 39 percent effective in preventing influenza-associated emergency department visits and hospitalizations so far this year, while children’s vaccines, primarily the intranasal one, fared better, at 72 percent to 75 percent effectiveness.

The CDC recommends influenza vaccination for everyone aged six months and older, with rare exceptions. Vaccines are particularly important for children, those with underlying health conditions, including pregnancy, and for seniors, as the immune system’s ability to fend off severe illness fades with age.

In terms of prevention, Hayden urged common-sense precautions such as keeping your distance from sick people by avoiding crowds, wearing a mask when that is unavoidable, and handwashing. 

In addition to vaccination, seniors and other people at risk also should consider taking flu antivirals for prevention if they are exposed to someone with influenza in their home or place of residence, Hayden said. If illness develops, prompt antiviral treatment can reduce the duration of the illness and the risk of complications. Such measures also can help prevent hospitals from becoming overburdened.

Learn more at www.makingofmedicine.virginia.edu.