COVID-19: Airborne Transmission / Antibody Response / Outcomes in Pregnancy

By Amy Orciari Herman

Edited by David G. Fairchild, MD, MPH, and Lorenzo Di Francesco, MD, FACP, FHM

Take a look at some of the latest findings on COVID-19:

Airborne transmission: A study published in JAMA Internal Medicine adds to growing evidence on the potential for airborne transmission of SARS-CoV-2 in closed environments with air recirculation. Roughly 125 Buddhists in China traveled on two heated buses to a 2.5-hour outdoor worship event in January (before public awareness of COVID-19 in that area); they were on the buses for a total of 100 minutes. The index patient began to experience COVID-19 symptoms that evening, upon return. All participants then underwent SARS-CoV-2 testing. Over one third of those on the same bus as the index patient were diagnosed with COVID-19. None on the other bus were infected. Passengers on the bus with the index patient became infected regardless of their proximity to the patient. The researchers conclude, "The investigations suggest that, in closed environments with air recirculation, SARS-CoV-2 is a highly transmissible pathogen."

Antibody response: The antibody response to SARS-CoV-2 infection may be durable through 4 months' follow-up, according to a study in the New England Journal of Medicine. Of some 1200 patients in Iceland who recovered from confirmed COVID-19, over 90% tested positive for SARS-CoV-2 antibodies (defined as positive results on two pan-immunoglobulin antibody assays covering IgM, IgG, and IgA). Antibody levels increased during the 2 months after diagnosis and then plateaued, remaining stable through the next 2 months of observation. Editorialists call for longer-term data but write, "This study provides hope that host immunity ... may not be fleeting and may be similar to that elicited by most other viral infections."

Outcomes in pregnancy: A review in The BMJ details outcomes among pregnant women with COVID-19. Researchers examined nearly 80 studies comprising over 13,000 pregnant or recently pregnant women with COVID-19 and 83,000 nonpregnant, infected women. Pregnant and recently pregnant women were less likely than nonpregnant women to develop fever or myalgia. They were more likely than nonpregnant women to require ICU admission (1.5% vs. 0.9%) and invasive ventilation (0.5% vs. 0.3%). Advanced maternal age, higher pre-pregnancy body-mass index, chronic hypertension, and pre-existing diabetes were independently associated with severe COVID-19 in pregnancy. The overall rate of preterm birth was 17%, while the rate of spontaneous preterm birth was 6%. In addition, about one fourth of babies born to COVID-19 mothers required admission to the neonatal unit. Risks for stillbirth and neonatal death did not appear to be increased.