Vaccine may fall short on flu virus

Early indications show this year’s shot to be only 10 percent effective against dominant strain

Congratulations, you already got your flu shot. Except now you’re home sick ... with the flu. What happened?

Early indications show this year’s vaccine may be only 10 percent effective against a dominant strain of the virus circulating the planet, and California public health officials say the greater Bay Area is one of two areas in the Golden State getting hit hardest now.

“We do know that flu vaccines are not 100 percent effective, and that their effectiveness varies from year to year,’’ said Dr. George Han, Santa Clara County’s assistant health officer and communicable disease controller.

The 10 percent figure — drawn from a recent New England Journal of Medicine report — is an Australian estimate of the vaccine’s benefit against one flu virus, the H3N2 virus, that was rampant during the Aussies’ most-recent flu season. Health officials there reported a record-high

number of flu cases and higher-than-average numbers of hospitalizations and deaths.

“They get the flu season half a year before we do,’’ said Han, who is bracing for what may be in store for the U.S. this flu season.

As the Journal article noted: “The implications for the Northern Hemisphere are not clear, but it is of note that the vaccine for this upcoming season has the same composition as that used in the Southern Hemisphere.’’

Experts say the strength of a flu vaccine all comes down to how well manufacturers — which work months in advance to produce shots — predict the strains of flu that will spread each year.

In general, the U.S. Centers for Disease Control and Prevention said that the current flu vaccines tend to work better against influenza B and influenza A (H1N1) viruses, and offer lower protection against influenza A (H3N2) viruses.

In the last flu season, the CDC said the vaccine was about 39 percent effective against all circulating flu viruses in the U.S., and only 32 percent against H3N2 viruses.

San Jose resident Charles Welsh wasn’t surprised his shot isn’t foolproof.

“Flu viruses change — it’s their best guess,’’ said Welsh, whose video conferencing company Zoom in downtown San Jose recently offered employees flu vaccines.

Welsh remembers getting the flu — even after a flu vaccine — but said it wasn’t severe.

But there are plenty of doubters. Akshay Agarwal, 28, was in the first-aid aisle at a San Jose Walgreens and insisted he’s never had the flu in his life — just colds and allergies — and has never gotten a flu vaccine.

While the flu season in California typically runs from October to March, and peaks in the Bay Area in January and February, we’re already suffering.

The state’s latest weekly flu report ending Dec. 2 shows the regions where flu is most concentrated include the Bay Area and Central Coast, as well as Imperial and San Diego counties and some parts of Riverside County.

Han said it’s too soon to say it’s particularly bad here; usually the CDC publishes data about flu trends in February.

At least two people in California have died from the flu this season, both reported in November. One victim was a Santa Clara County adult younger than 65 who had not received this year’s flu vaccine and suffered from other medical conditions that placed the person at greater risk of severe complications from the flu, county health officials said.

And a previously healthy male toddler in Orange County, who was between the ages of 1 and 3, died of complications related to influenza A.

Han said it’s never too late to get a vaccine, because even if someone does come down with the flu, it’s less likely to be a serious case if they have been vaccinated.

As he said: “It’s better to have some protection than nothing.’’