Paxlovid is an oral antiviral pill that can be taken at home to help keep high-risk patients from getting so sick that they need to be hospitalized.

Paxlovid, the pill that has become the go-to treatment for COVID-19 treatment, was granted full approval by the Food And Drug Administration (FDA) for the treatment of mild-to-moderate COVID-19 in adults at high risk for severe disease, including hospitalization and death. The drug also remains available to everyone 12 and older (weighing at least 88 pounds) who has mild-to-moderate disease and is at high risk for severe disease under an FDA Emergency Use Authorization.

According to Yale Medicine, the drug, developed by Pfizer, has a lot of positives: It had an 89% reduction in the risk of hospitalization and death in unvaccinated people in the clinical trial that supported the EUA, a number that was high enough to prompt the National Institutes of Health (NIH) to prioritize it over other COVID-19 treatments. Studies outside of the laboratory have since confirmed Paxlovid’s effectiveness among people who have been vaccinated. It’s cheaper than many other COVID-19 drugs (at this time, U.S. residents eligible for Paxlovid will continue to receive the medicine at no charge), and, perhaps most reassuring, it is expected to work against the latest Omicron subvariants.

“It’s really our first efficacious oral antiviral pill for this virus,” says Scott Roberts, MD, a Yale Medicine infectious diseases specialist. “It shows clear benefit, and it really can prevent hospitalization and death in people who are at high risk.”

Unfortunately, a new study in the Annals of Internal Medicine of US veterans prescribed nirmatrelvir-ritonavir (Paxlovid) during COVID-19 infections shows no difference in long-COVID rates among groups who took the antivirals and those who did not.

COVID-19 has been linked to the development of many post-COVID-19 conditions (PCCs) after acute infection. Limited information is available on the effectiveness of oral antivirals used to treat acute COVID-19 in preventing the development of PCCs. SARS-CoV-2 infection is believed to increase risk for several medical conditions long after acute illness.

Such post-COVID-19 conditions involve multiple organ systems and include pulmonary, cardiovascular, cerebrovascular, thromboembolic, neurocognitive, mental health, metabolic, renal, and gastrointestinal disorders. A study from the Centers for Disease Control and Prevention suggested that 1 in 5 COVID-19 survivors aged 18 to 64 years and 1 in 4 survivors aged 65 years or older experienced an incident condition that was potentially attributable to previous COVID-19.

In this new study, researchers used data from the VA’s Corporate Data Warehouse (a database of VA enrollees’ comprehensive EHRs) and the VA COVID-19 Shared Data Resource (CSDR), both of which are supported by the VA Informatics and Computing Infrastructure (VINCI), which integrates multiple data sources to provide patient-level COVID-19–related data. The CSDR includes information on laboratory-confirmed positive SARS-CoV-2 test results (by either nucleic acid amplification or antigen testing) within the VHA as well as SARS-CoV-2 tests performed outside the VHA and documented in VHA clinical records.

The researchers concluded that Paxlovid was not effective at reducing risk for many of the PCCs that were examined, including cardiac, pulmonary, renal, gastrointestinal, neurologic, mental health, musculoskeletal, endocrine, and general conditions and symptoms. And was associated only with a reduced risk for combined thromboembolic events 31 to 180 days after treatment.

The results of this study differed from those of a VA study by Xie and colleagues that reported that treatment with nirmatrelvir-ritonavir was associated with lower risk for 10 out of 13 PCCs.