Flu season is beginning earlier than usual in parts of the United States, with a notable surge in cases on the West Coast, particularly in the Pacific Northwest and California. This early start is primarily driven by an H1N1 strain, a subtype of influenza A.
Traditionally, flu season in the U.S. begins in the South and Southeast before spreading northward and westward. However, this year's pattern deviates from the norm, with an "early rise in flu cases" observed on the West Coast, according to Dr. Helen Chu, a respiratory infections specialist at the University of Washington School of Medicine.
"This year, it seems like we’re having a flu A surge very, very early," Chu stated. The H1N1 virus is believed to be a key factor due to its potential for easier spread and its ability to evade existing immunity.
While it remains too early to predict the full trajectory of the season, experts anticipate the flu will eventually spread to other regions as winter approaches. "Eventually, flu goes everywhere," said Dr. Andrew Pekosz, a professor at Johns Hopkins Bloomberg School of Public Health. He emphasized the importance of monitoring local health department updates for region-specific information, which can inform behavioral changes like masking in crowded areas.
There are three main types of influenza viruses: H1N1 and H3N2, both causing flu A, and influenza B. The current early surge is predominantly characterized by H1N1.
Despite uncertainties about the precise impact of the circulating strains on vaccine effectiveness, health officials stress that vaccination remains crucial. "Studies have also shown that even when the virus is a little mismatched from the vaccine, you can still see protection from severe disease," Pekosz noted.
Experts recommend getting vaccinated promptly, especially given the early start to the season. "I think it probably makes sense to get vaccinated a little bit earlier this year," Chu advised. Dr. Kaylan Christianer, a primary care doctor at Columbia University, echoed this sentiment, suggesting that "now is an excellent time to get a flu shot," noting that vaccines take about two weeks to become fully effective.
The flu vaccine is recommended for everyone six months and older. Specialized versions are available for certain age groups, including a high-dose vaccine for adults 65 and older and a new mRNA vaccine for adults aged 50 to 64. Officials emphasize that any flu vaccine is preferable to none. "People shouldn’t delay getting it to find the perfect vaccine, because at the end of the day, the most important thing is getting a flu vaccine," Christianer said.
For individuals averse to needles, the nasal spray vaccine FluMist is an alternative. Beyond vaccination, standard hygiene practices such as handwashing, considering masks in crowded places, and staying home when sick are advised to prevent the spread of respiratory illnesses.
Recent flu seasons have seen significant rates of infection, hospitalization, and death. A decline in vaccine uptake may have contributed to the severity of past seasons, according to Chu. Vaccination is highlighted as the most effective measure to protect individuals and communities from severe outcomes of influenza.