A recent study has found that just over 20% of people who take the covid-19 drug Paxlovid may still be contagious after coming off the treatment. Paxlovid, which is made up of the drugs nirmatrelvir and ritonavir, is effective in stopping the SARS-CoV-2 coronavirus from spreading in the body. However, the study showed that those who took Paxlovid were over 10 times more likely to experience "covid-19 rebound" compared to those who did not take the drug. Covid-19 rebound occurs when the virus increases in the body after an initial decrease.
The study, conducted by researchers at Massachusetts General Hospital, tracked the symptoms and viral loads of 127 people with mild to moderate covid-19. Of these, 72 took a five-day regimen of Paxlovid. Over the course of the study, 20.8% of those who took Paxlovid experienced covid-19 rebound, compared to 1.8% of those who did not have any treatment or a placebo. Covid-19 rebound was not associated with developing more severe symptoms, but it raises concerns about the potential for individuals to be contagious without realizing it.
Despite these findings, doctors say that the potential risks and benefits of Paxlovid should be considered for each individual and that the drug should not be discontinued. It is unclear why covid-19 rebound can occur with Paxlovid, but it is possible that some individuals may require longer than the standard five-day treatment regimen.
It is worth noting that previous studies, including some conducted by Pfizer, the manufacturer of Paxlovid, have also suggested the occurrence of rebound after treatment. The differences in results between trials may be due to variations in sampling times. The latest study involved testing participants three times a week and assessing their viral samples for replication, while previous research had limited testing to only three days.
Pfizer maintains confidence in the clinical effectiveness of Paxlovid in preventing severe outcomes from covid-19 in high-risk patients and believes that viral rebound is relatively uncommon and not uniquely associated with any specific treatment.
In summary, the study highlights the possibility of covid-19 rebound in individuals who have taken Paxlovid. While the drug is effective in reducing hospitalizations and deaths related to covid-19, doctors should carefully consider the risks and benefits for each patient. Further research is needed to understand why rebound occurs and to determine the most effective treatment duration.