(Bloomberg) -- Respiratory germs like RSV and Strep A surged across the world after Covid mitigation measures eased. Scientists in New Zealand blame waning antibody levels.
Antibody responses in 150 regular blood donors were measured across the pandemic’s first three years for immunity against a range of pathogens notorious for causing winter illnesses. While antibodies against the Covid-causing SARS-CoV-2 virus increased exponentially through March 2023 — reflecting vaccination and infection once New Zealand’s borders re-opened — protection against Group A Streptococcus and respiratory syncytial virus ebbed.
The decline reflected the bugs’ reduced circulation in communities amid mask-wearing, travel bans, and social distancing, the New Zealand researchers said in a new study. While those strategies staved off Covid until most people were vaccinated, they precipitated a rebound in other respiratory pathogens — which circulated at higher levels, ultimately finding their way to more vulnerable people, said co-author Nikki Moreland, an associate professor in infection and immunity at the University of Auckland.
“It’s really an unintended consequence of the pandemic restrictions that we need to be aware of,” Moreland said in an interview.
RSV — which can cause severe respiratory infections, including pneumonia, in young children and seniors — resurged in late 2021 before SARS-CoV-2 began spreading widely in New Zealand, indicating that the epidemic was driven by a decline in population-level immunity rather than any Covid-induced immune impairment that some scientists have suggested.
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