COVID-19: Antibody Duo Helps Prevent Infection / B.1.1.7 Variant Not Linked to More Severe Disease

By Amy Orciari Herman

Edited by David G. Fairchild, MD, MPH, and Jaye Elizabeth Hefner, MD

Check out some of today's highlights on COVID-19:

Antibody duo helps prevent infection: Regeneron's casirivimab-imdevimab monoclonal antibody combination cut the risk for symptomatic SARS-CoV-2 infection in household contacts of COVID-19 patients by 81%, the company reported on Monday. In a phase 3 trial, some 1500 people without SARS-CoV-2 antibodies or COVID-19 symptoms who lived with someone who'd tested positive for SARS-CoV-2 in the prior 4 days were randomized to receive subcutaneous casirivimab-imdevimab or placebo. By day 29, 7.8% of placebo recipients had developed symptomatic COVID-19, versus 1.5% of casirivimab-imdevimab recipients. Among those who did develop symptomatic infection, symptoms lasted for roughly 3 weeks among placebo recipients, versus 1 week for antibody recipients. In November, the antibody combination received emergency use authorization as a treatment for mild-to-moderate COVID-19 in high-risk patients, and late last week, the National Institutes of Health officially recommended it.

B.1.1.7 variant not linked to more severe disease: The B.1.1.7 variant of SARS-CoV-2, first identified in the U.K., does not appear associated with more severe disease than wild-type virus, according to new studies in The Lancet Infectious Diseases and The Lancet Public Health. In the first, researchers studied some 340 people admitted to U.K. hospitals with COVID-19 before mid-December 2020. Genomic sequencing revealed B.1.1.7 infection in 58% and other lineages in the rest. There was no significant association between B.1.1.7 and disease severity or death by day 28. Evidence did suggest higher viral load in those infected with B.1.1.7.

In the second study, researchers used data from a COVID-19 symptom app plus U.K. genomic analyses to track symptom severity in the U.K. as B.1.1.7 became increasingly prominent. Data on nearly 37,000 people with positive SARS-CoV-2 tests who reported symptoms on the app between September and December 2020 were included. Reports of symptoms and disease duration did not change as B.1.1.7 became more common. Reports of reinfection also did not increase. The researchers conclude that "existing testing and surveillance infrastructure do not need to change specifically for the B.1.1.7 variant" and "vaccines are likely to remain effective against the B.1.1.7 variant."