Clinical Edge Journal Scan

Clinical Edge Journal Scan Commentary: COVID-19 November 2021

Dr. Bhadelia scans the journals, so you don’t have to!

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Nahid Bhadelia, MD, MALD

Even as we approach two years of this pandemic, we are still learning about the risk factors for transmission and severity of disease from SARS-CoV-2 infection. In a large Swedish cohort study of nearly 1.8 million individuals which looked at the risk of an individual without immunity depending on how big their family was and how many members of the household already had prior infection or were vaccinated. Nordström et al found that non-immune individuals had increasingly lower chance of becoming infected (between 45% to 97% lower), and getting severe disease, as the number of people in their household who had prior immunity increased. The study did not differentiate between vaccine induced immunity or natural infection or adjust for geographical differences in disease activity. Because of the cohort design, the study could also not adjust for differences in behavior or occupational risk, but it does provide evidence of how growing population immunity could slow new infection rate. Unless of course the virus itself, changes significantly.

Similarly, Lin et al report the results of an international study of adults from 99 countries, which utilized longitudinal mobile based surveys to examine risk factors associated with SARS-CoV-2 infection. The mobile surveys captured baseline characteristics and behaviors of participants, and data was reported out for the study period of March to October 2020 (before vaccines were available). Adjusting for demographics, education level, a proxy for occupational risk, as well as medical comorbidities, authors found that greater number of non-household contacts, attending events with 10 or more individuals and restaurant visits predicted higher risk of SARS-CoV-2. Alternatively, older age was associated with lower risk, likely because of the protective behaviors undertaken by many in the older age group.

Lastly, the RECoVERED Study (Wynberg, at al), based in Netherlands, followed recently diagnosed laboratory confirmed SARS-CoV-2 patients for a year, initially with three in person visits (where disease severity was determined based on vital signs and level of care needed) within the first month of illness and then monthly online surveys. Authors utilized a survey examining severity of 18 symptoms based on the World Health Organization Case Report Form. Authors found 86.7% of those with initial severe disease [95% confidence interval {CI} = 76.5–92.7%]), 63.8% of those moderate disease 63.8% [95% CI = 54.8–71.5%], and 30.7% of those with mild disease [95% CI = 21.1–40.9%] had at least one persistent symptom at 12 weeks. Fatigue was the most common symptom reported at 12 weeks overall, but among those with moderate and severe disease, dyspnea and myalgia also persisted frequently. After one years of follow up, about one-fifth still had one persistent symptom. Over half of those with initial severe disease reported symptom persistence (52.5% [95% CI = 38.0–65.1%]). In a multivariable Cox proportional hazard model, female sex and higher BMI were associated with slower recovery. One limitation of the study was that was no control group recruited.

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