As of Dec. 16, the date of the most recent report from the California Department of Public Health, 10 people under age 65 had died from influenza-related illness statewide. Typically, only one or two deaths, and sometimes none at all, have been reported in the same time frame. The state does not track flu-related deaths among people age 65 and older.
The higher-than-usual number of fatalities — plus other reports of increased influenza activity.
What has some experts concerned, though, are reports that this year’s flu vaccine is not offering good protection against the strain that’s circulating most widely: Type A, subtype H3N2.
H3N2 “tends to be the strain of virus that most impacts the elderly, that causes the most complications, and up until this point the vaccine results have been quite disappointing,” said Dr. Randy Bergen, clinical lead for Kaiser Permanente’s flu vaccination program in Northern California. “Those things make us concerned that we’re going to have a lot of sick people.”
In Australia, hospital admissions for influenza were more than double what is reported in a normal season, according to officials there. Deaths more than tripled, but some of that increase may have been due to discrepancies in how fatalities are counted.
The increase in deaths in Australia was not necessarily because the flu virus in circulation was more severe. It was just infecting more people, experts said.
“They just had a lot of cases — the most they’ve had since 2009, which was a pandemic year,” said Dr. David Relman, an infectious disease specialist at Stanford Health Care.
One reason for the high rate of illness was the lack of vaccine protection, public health officials said. Australian officials believe that the H3N2 strain mutated in a way that weakened the impact of the vaccine.
The vaccine — which protects against three or four different influenza strains — reduced the overall risk of flu infection by about 33 percent. But for the H3N2 strain, officials believe it reduced the risk by only about 10 percent.
Nationwide, the flu season also seems to be starting a bit early, with elevated levels of hospitalizations and positive lab tests being reported in most states, according to the Centers for Disease Control and Prevention.