The Troubling Trends Pointing to a Severe Flu and RSV Season

Flu and respiratory syncytial virus (RSV) season has just begun in the northern hemisphere, and the consensus among experts is that the 2022-2023 season is shaping up to be more severe than in the past few (relatively mild) years. It might even be worse than seasons before COVID-19.

Health data company IQVIA has been analyzing data from insurance claims filed by doctors’ offices, hospitals, and urgent care centers in the country for three decades, and focused on case trends over the previous year. The team found that diagnoses of flu are already tracking at record highs. Even before flu season began, back in spring 2022, cases of influenza began trending well above average for the past three years, reaching nearly 950,000 cases weekly by mid-October (compared to around 400,000 at the same time in 2019, just before the pandemic began).

These higher rates aren’t completely unexpected. Influenza cases dropped significantly during the pandemic’s first two years, when people had less contact with one another and generally followed mitigation measures for controlling COVID-19, such as wearing masks and social distancing. Those behaviors helped to suppress the spread of flu. But, says Murray Aitken, executive director of the IQVIA Institute, the current flu numbers are “trending above every year since 2012 by a significant amount.”

Experts are also concerned about another troubling flu trend. Flu season in the southern hemisphere, which often gives the U.S. a preview of what to expect, struck early and hard this year. Australia, for example, confronted its worst flu season in five years, with nearly 30,000 lab-confirmed cases of influenza at its weekly peak in June; flu season there tends to peak later, between July and September.

Other respiratory viruses—SARS-CoV-2 and RSV—are also on the rise. COVID-19 is still responsible for about 260,000 infections each week in the U.S. on average, and labs that are part of the U.S. Centers for Disease Control and Prevention’s National Respiratory and Enteric Virus Surveillance System have reported a 500% increase in percent of positive tests for RSV from early September. RSV affects children and the elderly most severely. “This virus is hitting extremely hard this year,” says Dr. Juanita Mora, spokesperson for the American Lung Association and an allergist and immunologist at the Chicago Allergy Center. One reason why cases are climbing so quickly (especially among younger children), and so early in the season, could be because COVID-19 restrictions that closed schools and kept kids at home protected many of them from getting any infections over the past two years. “Generally 100% of kids will have had RSV by age two, but that’s not the case now,” Mora says. “Over the past three years, we have had no RSV season, so we have a cohort of kids who are lacking the immunity they might normally have.”

While a vaccine to protect kids from RSV exists, it’s only approved for kids at highest risk of developing severe disease, such as premature babies and those born with lung or heart disease. The vaccine requires monthly injections throughout the infection season, and most kids aren’t eligible to get vaccinated. For them, says Mora, the best protections are the same behaviors that shield kids from flu and COVID-19: keeping kids up to date with the flu and COVID-19 shots, washing hands often, and avoiding close contact with kids who are coughing or sneezing.

With flu and RSV cases rising so fast, hospitals in some parts of the country are already feeling strained. But the situation could get worse as new COVID-19 variants, some of which are evading vaccination protections, continue to proliferate this winter.

What’s contributing to the rapid and historic rise in respiratory diseases? It’s likely a combination of factors, including the mild seasons during the earlier part of the pandemic as well as sluggish vaccination rates against flu. Although it’s still relatively early in flu season, flu vaccine uptake is running nearly 9% behind where it normally is by now during pre-pandemic years.

Experts say that while these signs are concerning, the U.S. isn’t necessarily doomed to suffer a viral season as severe as countries like Australia. If more people get their flu and COVID-19 shots, that could dampen the effects of the viruses circulating more heavily than usual.