(Bloomberg) — Influenza is overtaking Covid-19 as the deadlier virus in the US this winter — the first time in five years the seasonal illness has surpassed the pandemic pathogen.
Since Covid began spreading widely in early 2020, it has killed almost 42 times more people in the US than the flu. Yet preliminary mortality data from the US Centers for Disease Control and Prevention shows that 2025 is emerging as a pivotal year for influenza.
While fears about growing bird flu outbreaks are dominating headlines in the US, seasonal influenza has reached its highest levels in over 15 years and has now surpassed Covid-19 deaths for the past two months, according to Peter Chin-Hong, an infectious diseases specialist and professor of medicine at the University of California, San Francisco.
The CDC estimates the flu has made at least 29 million people sick, caused 370,000 hospitalizations and resulted in 16,000 deaths since October 2024. Meanwhile, mortality from Covid-19 has been declining, driven by immunity from vaccination and prior infections, as well as the evolution of the SARS-CoV-2 virus, which now causes less severe complications.
“Flu seasons fluctuate — some years are worse than others, and this is a particularly severe one,” said Chin-Hong. He pointed to a raft of factors behind the resurgence from low vaccination rates to delayed treatment, particularly in groups that aren’t typically thought of as high risk.
The season has been dominated by H1N1 and H3N2 strains, with the latter notorious for causing more severe illness.
Kids have been hit especially hard, due to poor vaccine uptake, while South America’s recent flu season points to the possibility of reduced efficacy of the shots, according to Chin-Hong. The vaccination rate for children aged 6 months to 17 years has dropped from 58% in January 2020 to just 45% by the end of January 2025.
However, the most pressing concern is the delayed diagnosis and treatment of cases, particularly among those at risk of developing pneumonia and other severe complications. “High hospitalization and death rates suggest that at-risk people are not being diagnosed early enough for antivirals like oseltamivir to be effective in preventing severe illness,” Chin-Hong said.
Barriers to prescribing oseltamivir, along with the need for better early detection, remain key challenges.
“We need to change the narrative that respiratory viruses only cause serious illness in older adults, as we saw with Covid,” he said. “Flu targets the very young as well.”