It might feel like everyone around you is catching the flu or another virus, and that’s because we’re deep into the respiratory illness season in the Northern Hemisphere, which typically stretches from October to May. While flu hospitalizations have decreased since peaking in January, they are still considerably high, with signs of a possible resurgence. Additionally, the virus responsible for COVID-19 is showing high levels in wastewater, with a potential increase on the horizon. Respiratory syncytial virus (RSV) is also leading to hospitalizations, though not as many as the flu or COVID-19. Nevertheless, this year is turning out to be quite standard for respiratory viruses.

Influenza Update

This year’s flu season is largely consistent with past years, with the notable exception of the 2020–2021 season, which saw minimal flu activity due to COVID-19 precautions like masking and social distancing. The peak in weekly hospitalization rates was around January 4, after which there was a decline, although the Centers for Disease Control and Prevention suggest there might be delays in reporting. Recent data, which was released a few days late by the new administration, indicates a slight uptick in infections. There are concerns about the reduced effectiveness of this year’s flu vaccine, which could be contributing to the widespread illness, but overall, the severity isn’t deemed worse than in other seasons.

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According to Jennifer Nuzzo, a professor of epidemiology and director of the Pandemic Center at the Brown University School of Public Health, this year’s flu season started later than usual, but it is still intense. “It’s hard to say how things will unfold,” Nuzzo states.

Health authorities continue to recommend the flu vaccine, particularly for those over 65 or with underlying health conditions. Measures like wearing masks, avoiding large gatherings, and staying in well-ventilated areas can help reduce infection risks. For those who test positive for the flu, prescription antiviral drugs like Tamiflu are available.

Nuzzo finds some relief in the delayed start of this flu season, especially given the ongoing H5N1 bird flu outbreaks affecting birds and some mammals, which have led to human infections and a death in the U.S. The co-occurrence of H5N1 with the seasonal flu raises concerns about the potential for a new pandemic. “The delayed start has somewhat eased my concerns, but the threat of co-infection with both viruses is troubling,” she explains.

COVID-19 Insights

This winter has seen a smaller rise in COVID-19 hospitalizations compared to previous years, likely due to widespread immunity from vaccinations or past infections. There was a significant spike in COVID-19 cases last summer, which may have helped prevent a larger surge this winter.

Katelyn Jetelina, an epidemiologist who authors the popular newsletter Your Local Epidemiologist and advises the CDC, notes that the SARS-CoV-2 virus hasn’t changed much recently. Additionally, a higher percentage of people over 65 were vaccinated this season than last. Wastewater monitoring shows that virus levels peaked earlier and might be increasing again.

COVID-19 has not settled into a clear seasonal pattern like the flu and RSV, peaking more than once a year, including during the summer. “Much of it relates to human behavior as well as environmental factors. It’s a bit like shaking up a Boggle game each season to see what comes out,” Jetelina comments.

The COVID-19 vaccine remains the best defense against severe illness, with experts particularly urging older adults and those with weakened immune systems to stay current with vaccinations. For those at high risk who contract COVID-19, antiviral treatments like Paxlovid are recommended within the first five days of symptoms, though its benefits are less pronounced for those not at high risk, and it can interact with many medications.

COVID-19 still results in more deaths annually than the flu, though flu hospitalizations have doubled those of COVID-19 this winter, indicating a sharper peak. Whether SARS-CoV-2 will become less severe than the flu virus remains uncertain. “We can’t definitively say it won’t; the virus has surprised us before,” adds Nuzzo.

RSV Trends

RSV is experiencing a fairly typical year, with hospitalizations peaking earlier in the season and now declining. “It seems we’re at the peak or just past it, which isn’t too bad,” says Peter Chin-Hong, a professor and associate dean at the University of California, San Francisco, School of Medicine.

During the COVID-19 pandemic, RSV, like the flu, virtually disappeared in the 2020–2021 season, likely due to widespread masking and social distancing. However, it surged back with a strong early peak in the fall of 2022–2023 and another significant spike last year, closer to the typical seasonal timing.

Chin-Hong believes this year’s milder RSV season could be due to the virus returning to its usual pattern. Additionally, the recent approval of RSV vaccines for older adults and pregnant individuals may have offered more protection. “There’s still significant potential to vaccinate more of the older population,” he notes. Moreover, a new prophylactic antibody drug available for young children and newborns has seen good uptake, further helping to manage the spread of RSV.

Other Viral Concerns

Beyond the flu, COVID-19, and RSV, other harmful viruses are circulating. This season has seen a particularly severe outbreak of norovirus, a highly contagious gastrointestinal virus, with more than 1,000 outbreaks reported in the U.S. from August 1, 2024, to January 15, 2025—almost double the number reported last season.

Jetelina explains that the surge is likely due to mutations in the virus that have evaded existing immunity. “When the virus evolves and immunity in the population is low, outbreaks tend to occur,” she says. This season, an unusual variant of norovirus is responsible for nearly 70 percent of outbreaks.

Another virus, human metapneumovirus (HMPV), has been making headlines with a surge of cases in some Asian countries, although it’s not a new threat and is considered manageable. In the U.S., HMPV cases saw a slight increase in January, but levels have since declined.

Common cold viruses, including rhinoviruses, adenoviruses, and seasonal coronaviruses, are also prevalent, typically causing mild symptoms that can be managed with rest and hydration at home.

As always, if you’re feeling unwell, it’s wise to stay home if possible, limit contact with others, wear a mask, and wash your hands thoroughly, especially to combat norovirus, as hand sanitizers are ineffective against it.

Editor’s Note (2/5/25): This story has been updated based on the latest COVID wastewater data.