Flu season hits California early. Doctors are worried that it will be difficult for children

Fueled by a new strain of the virus, the flu is hitting California early — and doctors are warning that they expect the season to be especially difficult for young children.

Influenza concentrations found in contaminated water have risen in the San Francisco Bay Area, and testing rates are rising in Los Angeles County and Orange County, according to state and county data. Hospitalizations and emergency room visits for the flu are also on the rise in LA and Orange counties.

“We’re at the point now where we’re starting to see a significant increase in flu cases. This is a few weeks ahead of what we usually experience, but it’s very similar to what the Southern Hemisphere experiences with flu during their winter,” said Dr. Elizabeth Hudson, regional director of infectious diseases at Kaiser Permanente Southern California.

At Kaiser, flu cases are mostly seen in clinics so far, but hospitalizations tend to rise after Christmas. “We expect to see the same this year,” Hudson said.

“The number of cases seems to be higher in the last flu season than we have seen in previous years,” he added.

Flu levels are high in San Francisco water and wastewater in San José, Sunnyvale and Palo Alto, according to WastewaterSCAN and the Santa Clara County Department of Public Health.

One area of ​​concern this winter has been the rise of a subclade, known as H3N2 Flu A subclade K, that appeared in late summer. That was months after officials decided which type of flu vaccine to target.

Subclade K “causes an active, early, and endemic influenza season in the Northern Hemisphere,” the California Department of Public Health said.

It is unclear whether subclade K will reduce the effectiveness of this year’s flu shot. Newly released data from Britain showed that this season’s vaccines were 70% to 75% effective against hospitalizations in children with the flu, and 30% to 40% effective in adults, which is expected, the US Centers for Disease Control and Prevention noted.

This suggests “that the flu vaccine remains an effective tool in preventing flu-related hospitalizations this season,” according to the agency.

However, the intended effectiveness of the flu vaccine against symptomatic disease caused by the new subvariant remains uncertain, the World Health Organization said.

Overall, flu rates in LA County remain low, but are increasing. Across California, flu hospitalizations are also low but increasing.

At the national level, health indicators remain low, according to the CDC.

But experiences in other states have led some experts to worry that another severe flu season could be on the horizon for California.

Australia’s flu season, unlike California’s, came earlier than usual, hit hard and was particularly hard on the nation’s children.

Japan, Taiwan and Britain also reported early increases in their flu seasons.

“Whether this season is going to be tough, only time will tell,” Hudson said of California. “We know we have a mutation … that can make the flu vaccine less effective. But the vaccine still provides excellent protection against hospitalization and death, even if there is a mutated strain circulating.”

Based on what’s happening in the Southern Hemisphere – especially in Australia – “we expect this season to have a negative impact on children under 10,” Hudson said.

Three flu-related deaths of children have been reported nationally this season, including two on Friday.

During the flu season that ended in September, 280 children died from the flu – the most since the 2009-10 swine flu pandemic season.

Overall, the 2024-25 season is considered to be the worst flu season since 2017-18, and it hit adults hard as well. At least 38,000 people died from the flu last season, health authorities estimate.

Just over half of the children who died from the flu had underlying medical conditions, and 89% of those who died were not vaccinated, according to the CDC’s National Center for Immunization and Respiratory Diseases.

Among children who died from the flu last season, the most common complications that occurred before death were shock or sepsis, pneumonia, acute respiratory distress syndrome, seizures and brain injury.

Early detection of the flu can help prevent the worst by giving those who are ill time to take antiviral drugs such as Tamiflu. Three out of five children who died from the flu in the 2024-25 season never received antiviral medication.

Early warning signs of flu complications in children include difficulty breathing; green lips or face; ribs taking each breath; chest pain; severe muscle pain, when the child may refuse to walk; dehydration, symptoms including no urine for eight hours or tears when you cry; fainting; fever over 104 degrees that is not controlled with medication; fever or cough that gets better but returns or gets worse; and any fever in newborns under 12 weeks of age.

Since the respiratory virus season officially began on October 1, the CDC estimates there have been at least 1,900 flu-related deaths, 49,000 hospitalizations and 4.6 million infections nationwide.

Doctors have been urging everyone to get the flu vaccine — the CDC recommends it for everyone 6 months and older.

But vaccination rates have been declining. Among children aged 6 months to 17 years old, approximately 40.8% were vaccinated as of the first week of December, according to the National Immunization Survey. Last season before the COVID-19 pandemic, flu vaccination rates were the highest for this time of year, at 51.2%.

At the end of last flu season, only 49.8% of children and youth were vaccinated, the study estimated, down from 62.4% who had received the shot at the end of the 2019-2020 flu season.

Flu vaccination declines have been seen locally, too. “Significantly, fewer flu vaccines have been given this year compared to the same time last year,” the Orange County Health Care Agency said.

It takes about two weeks for immunity to build, but getting vaccinated as soon as possible before traveling or seeing friends and family “helps keep you and your loved ones safe,” the LA County Department of Public Health said in a statement to The Times.