COVID-19 research focuses on nosocomial transmission, risk stratification, vaccines

Recent studies showed that the risk of catching SARS-CoV-2 in a hospital is low for patients and varies by job and preventive measures for health care workers. A model and a serology study identified patients with worse outcomes from COVID-19. Vaccine studies were positive, but concerns arose about safety.

Multiple recent studies looked at spread of SARS-CoV-2 in health care facilities. Reassuring evidence was offered by an analysis of patients treated at an academic health center in Boston in early March through May, published by JAMA Network Open on Sept. 9. A total of 9,149 patients were admitted to the hospital and 7,394 SARS-CoV-2 tests were performed; 697 COVID-19 cases were confirmed. Only 12 of the 697 cases (1.7%) first tested positive on hospital day 3 or later, and only one was deemed hospital-acquired, most likely from a presymptomatic spouse who visited daily before visitor restrictions began. Of 8,370 studied patients with hospitalizations unrelated to COVID-19, 11 (0.1%) tested positive within 14 days of discharge, and only one case was deemed likely to be hospital-acquired, with the exposure unknown. The study authors concluded that “with rigorous infection control measures, nosocomial COVID-19 was rare.”

A study published by Thorax on Sept. 11 looked at the prevalence of SARS-CoV-2 virus and antibodies among asymptomatic British hospital staff. Of the 545 participants, 13 (2.4%) had positive nasal swabs and 126 (24.4%) had antibodies on serology testing. Seroprevalence was greatest among those working in housekeeping (34.5%), acute medicine (33.3%), and general internal medicine (30.3%) and significantly lower in intensive care (14.8%). This finding “strongly supports the conclusion that differential risk of SARS-CoV-2 exposure exists within the hospital environment,” likely due to differences in personal protective equipment, the authors said.

Another study, published as a brief report by Clinical Infectious Diseases on Sept. 8, measured reported health care worker exposures to the virus before and after a hospital in Alabama implemented universal masking and testing. Implementation of masking reduced high-risk exposures by 68%, and universal testing further decreased them by 77%. The authors concluded that their experience “suggests this approach is feasible and protective to [health care workers] when expedited testing is available.”

Two studies offered methods for risk-stratifying patients hospitalized with COVID-19. A study published by The BMJ on Sept. 9 used data from more than 50,000 patients treated at 260 U.K. hospitals to develop the 4C Mortality Score. It included eight variables available at initial assessment (age, sex, number of comorbidities, respiratory rate, peripheral oxygen saturation, level of consciousness, urea level, and C-reactive protein) and showed high discrimination with excellent calibration. The authors said that the score could guide decisions about where and how to treat patients. “Patients with a 4C Mortality Score falling within the low risk groups (mortality rate 1%) might be suitable for management in the community, while those within the intermediate risk group were at lower risk of mortality (mortality rate 10%; 22% of the cohort) and might be suitable for ward level monitoring. … Meanwhile patients with a score of 9 or higher were at high risk of death (around 40%), which could prompt aggressive treatment, including the initiation of steroids and early escalation to critical care if appropriate,” they wrote. Another study, published by Clinical Infectious Diseases on Sept. 5, used plasma and serum samples from 123 Norwegian patients to determine that SARS-CoV-2 RNA was found in about half of patients, but it was detected more frequently, and at higher levels, in patients who were admitted to the ICU and/or died.

Finally, there were multiple recent developments in SARS-CoV-2 vaccines. Positive results were published from a Russian trial by The Lancet on Sept. 4 and from an Australian trial by the New England Journal of Medicine on Sept. 2. On Sept. 9, AstraZeneca announced a voluntary pause of its vaccination trials to allow an independent committee to review a single unexplained illness that occurred in a phase 3 trial in the U.K. AstraZeneca then announced on Sept. 12 that trials in the U.K. would resume after the country's Medicines Health Regulatory Authority said it was safe to do so; however, trials in other countries remain paused. On Sept. 8, nine pharmaceutical companies announced a pledge to only submit a vaccine for FDA approval or emergency use authorization after demonstration of safety and efficacy through a phase 3 study.