California is currently grappling with one of the worst flu seasons in recent years, leading to a significant rise in hospitalizations and prompting health officials to warn that the virus may continue to circulate at high levels for weeks. According to data from the California Department of Public Health, the flu test positivity rate at clinical sentinel labs soared to 27.8% for the week ending February 1, marking a peak not seen since the onset of the COVID-19 pandemic in early 2020. This surge surpasses even the peak of the “tripledemic” winter of 2022-23, when hospitals were overwhelmed by simultaneous outbreaks of flu, COVID-19, and respiratory syncytial virus (RSV).
Dr. Peter Chin-Hong, an infectious disease expert at UC San Francisco, noted that this is the first time since the pandemic that flu has taken center stage in discussions about public health. He emphasized that the situation is still escalating, indicating that the flu season is far from over. Health officials are particularly concerned about the impact on children, with at least ten pediatric flu deaths reported this season in California, including three teenagers from San Diego County. Tragically, none of these teens had received a flu vaccine, which Dr. Ankita Kadakia, the county’s interim public health officer, called the best protection against severe illness.
Nationally, the Centers for Disease Control and Prevention (CDC) estimates that there have been at least 11,000 flu-related deaths this season, including 47 children, alongside at least 250,000 hospitalizations. Dr. Chin-Hong highlighted that while many may have grown accustomed to thinking of children as generally safe from severe illness, influenza can be particularly dangerous for younger populations. Pediatricians across the country are reporting a significant increase in flu cases among children.
Compounding the crisis is an alarmingly low vaccination rate against the flu among children this winter, which is the lowest since at least the 2019-20 season. As of late January, only 44.5% of children aged 17 and younger across the United States had received their flu vaccine, down from 49.1% the previous year. In California, the vaccination rate stands at 47.7%, also a significant drop from 53.7% last year.
Health officials recommend that everyone aged six months and older receive a flu shot, ideally by the end of October, to enhance protection against the virus during the peak winter months. Given the current severity of the flu season, officials are urging those who have not yet been vaccinated to consider getting the shot.
The flu strains circulating this season include H1N1, which caused the pandemic in 2009, and H3N2, known for causing more severe illness. Recent genetic analyses revealed that 54% of influenza type A viruses were H1N1, while 46% were H3N2. Surveillance data show that flu levels in California’s wastewater are currently classified as “very high,” with RSV levels also high and COVID-19 levels low.
Hospital admissions for flu in California are on the rise, with the latest report indicating a hospitalization rate of 10.1 new admissions per 100,000 people, the highest of the season. In Los Angeles County, the flu season has proven particularly potent, with a test positivity rate above 20% for seven consecutive weeks, peaking at 28.83% recently.
Experts caution that while the flu season is severe, COVID-19 and RSV activity remain low. The CDC predicts that emergency department visits for flu will continue to be high in most states, while COVID-19 visits are expected to remain lower than in previous winters. This winter could mark the first time during the COVID era that California does not experience a significant surge in COVID-19 cases, thanks in part to the immunity built up from previous infections and vaccinations.
Health officials are encouraging residents, particularly those at high risk for severe illness, to consider vaccinations for COVID-19 and RSV as well. With respiratory illnesses circulating widely, the importance of flu vaccinations remains critical as the state continues to navigate this challenging flu season.