Is flu going around in the United States?

Flu season in the US typically runs from October through May. Activity usually begins climbing in late October or November, peaks between December and February, and tails off through April. The exact timing and intensity vary considerably year to year and region to region, influenced by the circulating influenza subtypes and population immunity carried over from previous seasons.

The overall picture is tracked by the CDC through its weekly FluView report and NHSN hospital admissions data. The CDC classifies seasonal activity on a scale from minimal to very high, based on indicators like outpatient visits for influenza-like illness (ILI), laboratory-confirmed cases, and hospitalization rates. A season is considered severe when hospital admission rates climb past the thresholds observed in past severe years.

The flu (influenza) typically comes on abruptly with high fever, body aches, a dry cough, and significant fatigue. A cold develops more gradually and is usually milder, with symptoms like a runny nose, sore throat, and mild cough, rarely with fever in adults. The flu is more likely to cause serious complications, especially in older adults, young children, and people with chronic conditions.

The CDC recommends an annual flu vaccine for everyone aged 6 months and older, with rare exceptions. The shot is especially important for people at higher risk of complications: adults over 65, pregnant women, young children, and those with chronic conditions like asthma, heart disease, or diabetes. The vaccine takes about two weeks to become fully effective, so getting vaccinated early in the season offers the best protection.

Vaccination is the most effective single measure. Beyond that, frequent handwashing, avoiding close contact with visibly ill people, covering coughs and sneezes, and staying home when sick all reduce community transmission. Indoor ventilation and, in high-risk settings, well-fitted masks provide additional protection during peak season.