Tests indicate flu season has peaked in Sonoma County

As much of California grapples with the worst flu season since the 2009 swine flu pandemic, local experts say their testing suggests the spread of the virus may have peaked in Sonoma County.

Public health officials are still warning that the flu will continue to spread in the coming weeks.

“Even if we have peaked, many, many more people will still become ill with the flu this season and should take steps to protect themselves,” said Karen Holbrook, the county’s deputy health officer.

Thus far, throughout the state, the flu season has claimed the lives of 42 people under the age of 65, with 155 people in that age group hospitalized in intensive care units. No flu deaths among that age group have been reported in Sonoma County.

Public health officials do not track flu deaths and severe illness for those ?65 and older, because such flu deaths and severe illness is not uncommon among the elderly.

But locally, the flu season has not been as severe as in other parts of the state, and positive tests for both strains of the flu virus have declined two weeks in a row, said Dr. Gary Green, head of the infectious disease department at Kaiser Santa Rosa Medical Center.

Green said that 39 percent of all tests for the Influenza A and B between Jan. 8 and Jan. 14 have come back positive. That’s a significant decline from the previous week, when it was 48 percent, he said. The week before that, 49 percent of flu tests came back positive.

Green said most of the decrease is in Influenza A, while positive testing for Influenza B is “holding steady.” But Green said this year the H3N2 influenza A strain is the one causing more severe illness and leading to more hospitalizations and deaths.

“It’s down two weeks in a row, so we’re past the peak,” said Green.

In Sonoma County there have been 6 severe cases of flu illness and seven outbreaks in residential care facilities, said Holbrook. A severe case is one where someone under the age 65 is admitted to a hospital ICU.

During the 2009 H1N1 pandemic, there were 31 severe cases of flu-related illness in Sonoma County, including 11 deaths, Holbrook said.

Since then, the other bad flu season in Sonoma County was 2013-2014, which saw 26 severe cases and 7 fatalities, according to county records.

Holbrook said it’s too early to “definitively conclude” whether the flu season has in fact peaked. But she said that given the very large number of Kaiser patients in the county, the local care providers’ recent testing results are encouraging.

Green said it appears the flu season got an early start in Sonoma County, with the season moving “a little faster” through the local community. He said it appears enough people got vaccinated this year to develop greater herd immunity - the indirect protection that comes from a larger share of the population being immune to infection

Both Green and Holbrook said the flu season is still far from over and advised those who haven’t gotten their flu shot to do so. It usually takes two weeks for the vaccine to take full effect. They also advised people to practice good hygiene throughout the day, and to stay home from work or school if they are sick.

You can reach Staff Writer Martin Espinoza at 707-521-5213 or martin.espinoza@pressdemocrat.com. On Twitter @renofish.