Maryland Flu Cases Remain Low as New Strain Spreads
A mutated H1N1 virus is causing early flu activity on the West Coast and in the South, but local experts say Maryland has not yet seen a surge.
By Ryan Davidson ·
Flu activity in Maryland has not spiked yet, according to Johns Hopkins experts who spoke to WYPR on Thursday. The national surge is being driven by a mutated H1N1 strain. This virus is causing early flu season cases in other parts of the United States.
Researchers identified a mutation called G155E in an H1N1 influenza A strain. This change alters how the virus infects cells. It also appears to help the virus evade some existing immunity. The mutation was first detected in Japan in May. Clinics there reported flu visits running about seven times higher than in early October of last year.
In the United States, the early increase began on the West Coast and has appeared in the South. For the week ending Sept. 26, about 3.4% of respiratory specimens tested in clinical labs were positive for influenza. Northeastern University public health researchers reported this figure is roughly eight times the level from the same time last year, citing CDC data. The CDC counted almost 5,000 laboratory-confirmed flu hospitalizations nationwide in the week ending Oct. 17.
Johns Hopkins immunology researcher Andrew Pekosz said there is no cause for concern in Maryland right now. He urged unvaccinated people to treat the current window as a final call. The Maryland Department of Health tracks flu activity weekly through FluWatch reports. These reports are the primary source for state level data.
Last season provides a benchmark for comparison. The 2025-26 season was dominated by a different strain, influenza A/H3 subclade K. It peaked in late December. The state health department reported that hospitalizations and deaths were higher than in most recent seasons but lower than in the 2024-25 season.
This season's vaccine offers partial protection against the new H1N1 variant. Preliminary lab testing shows the vaccine can still recognize the strain. Pekosz described the protection as partial rather than complete. Early estimates from Northeastern researchers put vaccine effectiveness at 30% to 40% against doctor visits and hospitalizations. Full effectiveness data will not be available until midwinter. Samuel Scarpino of Northeastern noted that a 30% effective vaccine in 2022-23 prevented more than 70,000 hospitalizations nationwide.
Dr. Anna Durbin, director of the Johns Hopkins Center for Immunization Research, told WYPR, “I think it’s really important for everyone to get a flu vaccine as soon as possible.” This is also the first season an mRNA flu vaccine is available. It is limited to people 50 and older. Researchers are monitoring how it compares with traditional shots. Baltimore residents can get shots at pharmacies, doctor's offices, and local health department clinics. The next few weeks will show if the H1N1 wave reaches the state before Thanksgiving.
