Latest COVID-19 research focuses on PASC, prophylaxis, pregnancy

Recent COVID-19 research looked at postacute sequelae, postexposure prophylaxis, and effects of infection or vaccination during pregnancy.

The first study, published by the New England Journal of Medicine (NEJM) on July 17, used Veterans Affairs data to match 441,583 veterans with SARS-CoV-2 infection between March 1, 2020, and Jan. 31, 2022, with 4,748,504 uninfected controls to estimate the cumulative incidence of postacute sequelae of COVID-19 (PASC) with different viral variants. It found that, among unvaccinated patients, the cumulative incidence of PASC during the first year after infection was 10.42 events per 100 persons (95% CI, 10.22 to 10.64) in the pre-delta era, 9.51 per 100 (95% CI, 9.26 to 9.75) in the delta era, and 7.76 per 100 (95% CI, 7.57 to 7.98) in the omicron era. Among vaccinated patients, the incidences were 5.34 (95% CI, 5.10 to 5.58) and 3.50 (95% CI, 3.31 to 3.71) per 100 in the delta and omicron eras, respectively.

Decomposition analyses found that there were 5.23 fewer PASC cases per 100 during the omicron era than during the previous eras combined. Most of that effect (71.89%) was attributable to vaccines, with the rest era-related, the study authors calculated. "Analyses of PASC according to disease category showed a lower risk of sequelae in most disease categories but a higher risk of gastrointestinal, metabolic, and musculoskeletal disorders during the omicron era than during the pre-delta and delta eras combined," they said. The study's results "suggest that vaccine uptake will be key to maintaining the lower cumulative incidence of PASC" but also that "a substantial residual risk of PASC remains among vaccinated persons who had SARS-CoV-2 infection during the omicron era," the study concluded.

The study offers three main messages, according to an accompanying editorial, including that vaccination and viral variants affect the risk of PASC. "Third, the study suggests that new cases of PASC may continue unabated, owing to a potentially greater prevalence of metabolic dysfunction and its associated coexisting conditions among persons infected during the omicron era," said the editorialist, before expressing hope that the results "may help guide clinicians in understanding the perplexing clinical course of PASC."

The second study, also published by NEJM on July 17, was a manufacturer-funded, phase 2-3 trial to assess the efficacy and safety of nirmatrelvir-ritonavir (Paxlovid) for postexposure prophylaxis. It randomized 2,736 participants who had a household contact with COVID-19 but tested negative to either five or 10 days of the drug or placebo and found no significant differences in the rate of symptomatic, confirmed infection by day 14. Adverse events were similar across trial groups.

The final study, published by The BMJ on July 17, used Nordic registry data to examine the effects of COVID-19 infection or vaccination during the first trimester of pregnancy. Of 343,066 liveborn singleton infants in Sweden, Denmark, and Norway in 2020 to 2022, 5.2% had a major congenital anomaly. Adjusted odds of an anomaly were not significantly different if a COVID-19 infection or vaccination against COVID-19 had occurred during the first trimester. Among other limitations, the study did not include stillbirths or miscarriages, the authors noted. "Overall, our findings support the current recommendations to vaccinate pregnant women against covid-19," they concluded.