This starts off with a look at some familiar studies from the CDC link above, but then moves on to some interesting information, beginning with the section “when to receive treatment”, plus a couple after that.
What the Latest Research Says About Paxlovid.
A bunch of things jumped out at me, just snipping a couple:
Some have speculated that rebound occurs because 5 days of treatment is inadequate to clear SARS-CoV-2. However, Pfizer compared 5-day and 10-day treatment courses in a trial of nirmatrelvir-ritonavir for postexposure prophylaxis and did not find a statistically significant advantage to the longer treatment.
Does Treatment Reduce the Risk of Long COVID?
Again, the findings have been mixed.
Higher acute viral load or prolonged shedding may be associated with post–COVID-19 condition (PCC), commonly known as long COVID, so scientists have speculated that nirmatrelvir-ritonavir might help minimize the risk.
A study published in March 2023 in JAMA Internal Medicine found that among people with SARS-CoV-2 infection who had at least 1 risk factor for progression to severe disease, treatment with nirmatrelvir-ritonavir was associated with a reduced risk of PCC. Researchers used the Veterans Affairs health care databases to identify high-risk patients with a positive SARS-CoV-2 test result in 2022. Their cohort included approximately 282 000 patients, of whom about 36 000 were treated with nirmatrelvir-ritonavir.
And a study of approximately 2.3 million Medicare enrollees diagnosed with COVID-19 in 2022 found that nirmatrelvir-ritonavir and molnupiravir were associated with a small reduction in PCC incidence. The findings were reported in October 2023 in JAMA Internal Medicine.
But an observational cohort study published in January of this year found no difference in the development of PCC in treated and untreated patients. The study included 4684 vaccinated individuals diagnosed with COVID-19 who were part of the COVID-19 Citizen Science study, an online cohort study with more than 100 000 participants.
Of the cohort of 4684, about 1 in 5 received nirmatrelvir-ritonavir for acute SARS-SoV-2 infection. About a third of both the treated and the untreated patients responded to surveys at least 3 months after SARS-CoV-2 infection. The surveys asked about PCC symptoms and rebound in symptom or test positivity.
The study found that nirmatrelvir-ritonavir use was not associated with a lower prevalence of PCC. And among the treated participants who answered rebound questions, neither test-positivity rebound nor symptom rebound was associated with higher prevalence of PCC.
“It really was surprising to us,” lead author Matthew Durstenfeld, MD, MAS, said of the lack of an association between treatment and PCC. After all, he told JAMA in an interview, even people with mild COVID-19 can develop PCC, and data show that nirmatrelvir-ritonavir decreases viral load.
However, “we were pleasantly surprised” to find that rebound wasn’t linked to a greater risk of PCC, said Durstenfeld, a cardiologist and clinical researcher at the University of California, San Francisco. “We were wondering if rebound was kind of an early warning sign of long COVID.”
So many confusing indications, although I admit I have a slight bias toward controlled studies versus observational studies.