Covid-19 rebound affects 1 in 5 people after taking Paxlovid

Covid-19 rebound, when the virus increases in the body after initially decreasing, affected just under 21 per cent of people after they took Paxlovid in a trial, compared with fewer than 2 per cent not on the treatment

By Christa Lesté-Lasserre

14 November 2023

Paxlovid, which is made up of the drugs nirmatrelvir and ritonavir, can stop the SARS-CoV-2 coronavirus from spreading in the body

Cryptographer/Shutterstock

Just over one in five people who take the covid-19 drug Paxlovid may be contagious after coming off the treatment, but doctors say this isn’t a reason to stop prescribing it.

In a recent study, people who took Paxlovid, which is made up of the medicines nirmatrelvir and ritonavir, were just over 10 times more likely to experience “covid-19 rebound” – when the virus increases in the body after an initial decrease – compared with those who didn’t take it, suggesting that the former group may still be contagious post-treatment.

Paxlovid can reduce covid-19-related hospitalisations and deaths by stopping the SARS-CoV-2 coronavirus from growing in the body. Although often effective, many people have reported covid-19 rebound after coming off the drug.

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“We knew it was an actual public health issue; what we didn’t really know was how common it was,” says Mark Siedner at Massachusetts General Hospital.

To learn more, Siedner and his colleagues tracked the symptoms and viral loads – the amount of the virus in swabs – of 127 people with mild to moderate covid-19. Of these, 72 took a five-day regimen of Paxlovid.