A study found that patients who took Pfizer’s Paxlovid within five days of testing positive for … [+]
Paxlovid has been trending on Twitter. But it’s not because some politician decided to call another politician “Paxlovid” before the midterm elections. Instead, there’s been some potentially, possibly encouraging news about the antiviral medication for the long run. A new study described in a pre-print uploaded on November 5 to medRxiv found that those who had taken Paxlovid within five days of testing positive for Covid-19 were 26% less likely to have gone on to experience long Covid symptoms. That’s encouraging because our society is still short on things to do about preventing long Covid, otherwise known as post-acute sequelae of Covid-19 or having persistent symptoms after you’ve recovered from a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, take any findings from this study with a grain of salt or maybe two, three, or even twenty-seven grains of salt because it did have a number of limitations.
Sure, Paxlovid, which is Pfizer’s brand name for the combination of nirmatrelvir and ritonavir, is supposed to prevent the virus from replicating in your body if you take the medication soon enough after you get infected. Sure, having less virus in your body in theory might mean less of an impact on your body including the possibility of long Covid. But this was an observational cohort study that is currently described in only a pre-print and not a peer-reviewed publication in a reputable scientific journal yet. Plus, Paxlovid can have interactions with a number of different medications. So to borrow the name of that 2000’s HBO TV series starring Larry David and Cheryl Hines, curb your enthusiasm a bit for now.
For the study, three researchers from the Veterans Affairs St. Louis Healthcare system (Yan Xie, Taeyoung Choi, and Ziyad Al-Aly) searched the US Department of Veterans Affairs healthcare databases to find patients who had tested positive for SARS-CoV-2 from March 1, 2022 to June 30, 2022. If you recall, that’s when Omicron variants were the alpha-dog versions of the SARS-CoV-2, fueling yet another surge of Covid-19. The researchers narrowed this group of patients down to those who had at least one risk factor that meant thy were more likely to progress to severe Covid-19 such as being over 60 years of age, currently smoking tobacco, or having a body mass index of over 25, cancer, cardiovascular disease, kidney disease, chronic lung disease, diabetes, immune dysfunction, or hypertension. They also excluded folks who were hospitalized at the time of the positive test, died during the ensuing 30 days after being diagnosed with Covid-19, already had liver disease, or already had very significant kidney problems.
From this remaining group of over 56,000 Veterans, the trio of researchers identified 9,217 who had taken Paxlovid within five days after having positive Covid-19 tests. They then selected a matched control group of 47,123 Veterans who hadn’t received any Covid-19 antiviral or antibody treatment during their acute phase of their SARS-CoV-2 infections. They tried to make sure that the distributions of major demographic characteristics such as age and sex were similar in the Paxlovid and control groups.
One key limitation is that the study population wasn’t exactly super-diverse. The average age was around 65 years with a standard deviation of 13.93 years. Nearly, three-quarters (74.59%) were White. This was also largely a “you got male” situation too with 87.64% being men.
Covid-19 vaccination rates among the study patients were a little bit higher than that of the general U.S. population with a little over 83% having gotten at least one dose of the vaccine compared to 80.2%. This was lower than the 91.2% of U.S. adults who have gotten at least one dose of the vaccine though.
With the Paxlovid and control groups identified, the researchers then did combed through the patients’ medical records to determine what happened subsequently to all of them. The researchers looked at who ended up developing any of the 12 following long Covid issues: ischemic heart disease, dysrhythmia, deep vein thrombosis, pulmonary embolism, fatigue, liver disease, acute kidney injury, muscle pain, diabetes, neurocognitive impairment, shortness of breath and cough. They determined who had gotten hospitalized and died as well.
The long and the short of it is that the group treated with Paxlovid was 26% less likely to have suffered long Covid symptoms after the initial infection. They also were less likely to have experienced ten of the 12 long Covid issues that the researcher looked for, basically all of them besides a new diagnosis of diabetes and cough. Those in the Paxlovid group were also 30% less likely to have been hospitalized and 48% less likely to have died from Covid-19 than those in the control group.
All of this sounds promising. Before you jump into a mosh pit of maskless people, thought, remember this was only a pre-print. Anyone with an Internet connection, opposable thumbs, and some time on their hands can upload a pre-print on to a web site. This pre-print has not yet undergone peer-review. A pre-print is to a peer-reviewed publication in a reputable scientific journal what a person staging a super-hero movie with his or her cats on YouTube is to a real “Avengers” movie shown in the theater.
Moreover, such an observational cohort study can only show associations or correlations, which does not necessarily mean cause-and-effect is at play. For example, Two variables may be associated without a causal relationship. For example, Wayne W. LaMorte, MD, PhD, MPH, at the Boston University School of Public Health has pointed out that there’s statistical association between the number of people who have drowned in a swimming pool and the number of film appearances Nicolas Cage has made in a given year. That doesn’t necessarily mean that everyone should freak out should Cage decide to film “Leaving Las Vegas Again” or “Ghost Rider 3.” OK, maybe the latter would be a problem, but the point is that other unmeasured factors may be driving the outcomes in an observational cohort study. It not clear whether the VA patients taking Paxlovid were different in other unmeasured ways from those in the control groups. For example, could those who took Paxlovid have been more likely to have worn face masks, maintained social distancing, and taken other Covid-19 precautions so that they were exposed to lower infectious doses of the virus in the first place? Could those taking Paxlovid have had better access to health care in general?
Plus, you can never really draw strong conclusions from just one study. That would be like judging the TV series “Heroes” and “Riverdale” based only on their first seasons. The latter series sort of went off the rails when Kevin started making tickle fetish videos for cash. More studies are needed to either confirm whether Paxlpovid indeed can reduce the risk of long Covid and by how much.
Nevertheless, it is helpful to know that possibly, potentially, maybe, perhaps Paxlovid might be able to reduce your risk of getting long Covid. Of course, the most effective way to avoid long Covid is to not get Covid-19 in the first place. Being vaccinated and boosted may reduce your risk somewhat too, potentially by 30 to 50%. But researchers have been longing to find more ways to reduce the risk of long Covid because as long as the pandemic continues, getting long Covid is a big concern. And the pandemic is not over, no matter what politicians may tell you before the midterm elections.
