Discussion: The flu outbreak — what you need to know

The flu season this year is bad. How bad? With the high number of people getting sick, many are comparing this year to the swine flu epidemic nine years ago. Last Friday, the CDC predicted that as many as 56,000 Americans will die of flu this year.

So, why is it so bad this year?

"The flu is so bad this year for a few reasons we understand and some we don't," said Dr. Marc Lipsitch, professor of epidemiology and director of the Center for Communicable Disease Dynamics at Harvard. "The ones that we understand are that it is predominantly an H3N2 year — that's one of the four strains of flu that circulates every year. And H3N2 is known to be the most severe in terms of the symptoms and the consequences it causes for people.”

Lipsitch says we don’t really understand why H3N2 is predominating this year but suggests that another reason the flu is bad this year is that while the vaccine is reasonably effective against influenza B, but it is not very effective against H3N2.

Initial studies out of Australia and Canada have found the shot had only a 10 to 20 percent efficacy rate in those countries against the H3N2 strain.

According to Lipsitch, that’s been a problem in the past during an H3N2 year and that it’s not really understood why it has been the case since the strain emerged in 1968 as a pandemic strain.

“It’s always been the cause of more severe seasons,” Lipsitch said.

With the low efficacy rate, is it even worth getting the flu shot?

“The flu season is still underway and it will still be going for several weeks, so there is a benefit of getting the flu shot now,” Lipsitch urged. "Even 10 or 20 percent in reduction of risk is better than no reduction in risk. It’s a safe vaccine. I had it and your arm hurts for a day and then it stops hurting. It’s a small price to pay compared to getting the flu.”

On Tuesday, Feb. 13, 2018, Lipsitch joined Alfred DeMaria, medical director for the Bureau of Infectious Disease of the Massachusetts Department of Public Health, Yonatan Grad, assistant professor in the Department of Immunology and Infectious Diseases at Harvard and Tim Uyeki, chief medical officer, Influenza Division, National Center for Immunization and Respiratory Diseases at the CDC for a discussion about the flu outbreak in a panel moderated by The World’s Livable Planet editor Peter Thomson.

You can watch a video recording of the live discussion above.