H3N2 flu is surging — and just had the ‘perfect environment’ for a spike

In the week ending Dec. 20, one in four (25.6 per cent) of every influenza test conducted in the U.S. came back positive, the U.S. CDC said.

The H3N2 flu strain is landing more people in the hospital in the United States, and experts are urging Canadians to exercise caution amid a “perfect environment” for spread and a fresh round of case numbers expected in this country next week.

The U.S. Centers for Disease Control and Prevention (CDC) estimates that 7.5 million Americans have been infected and 81,000 have landed in the hospital this flu season, the health agency said on Thursday.

“Some parts of the United States are reporting the highest rates of flu hospitalizations since they’ve kept records,” said Dr. Fahad Razak, internal medicine physician at St. Michael’s Hospital and professor at the University of Toronto.

In the week ending Dec. 20, one in four (25.6 per cent) cases of every influenza test conducted in the U.S. came back positive, the CDC said.

This was a sharp increase from 15.7 per cent of tests coming back positive in the week ending Dec. 13 and nine per cent for the week ending Dec. 6.

For the week ending Dec. 20, 19,053 people were admitted to hospital in the U.S. with the flu. Five children died in the U.S. in the week ending Dec. 20 after an association with influenza, the CDC added.

The dominant strain in the U.S. and Canada this year is a strain called H3N2 subclade K.

Canadians should be cautious in the weeks coming out of the holidays, Razak said.