From the Curator-in-Chief's Desk—July 23, 2021

Global COVID-19 cases and deaths continue to rise this week, fueled by the Delta (B.1.617.2) variant. Over 80% of new COVID-19 cases are caused by the Delta variant in the U.S., where cases have tripled in the last 2 weeks. Fortunately, current vaccines reduce SARS-CoV-2 transmission. Prunas, O., et al. determined the Pfizer and BioNTech BNT162b2 vaccine is 88.5% effective at preventing SARS-CoV-2 transmission among households. COVID-19 vaccines are a safe and effective way to help reduce the spread of SARS-CoV-2.

COVID-19 vaccines are also highly effective against SARS-CoV-2 variants. Lopez Bernal, J., et al. assessed vaccine effectiveness of 2 doses of the BNT162b2 and the AstraZeneca ChAdOx1-S nCoV-19 vaccines against symptomatic disease. The authors reported the vaccine efficacy of BNT162b2 is 93.7% against the Alpha (B.1.1.7) variant and 88% against the Delta variant. The ChAdOx1-S nCoV-19 vaccine is 74.5% and 67% effective against the Alpha and Delta variants, respectively. Vaccines also reduce the severity of disease for individuals infected with the Delta variant. Kumar, V., et al. analyzed disease severity in vaccinated and unvaccinated patients hospitalized with COVID-19 infected with the Delta variant. Compared to unvaccinated patients, fully vaccinated patients had 50% lower rates of needing a ventilator and mortality.

The need for vaccine boosters is a current debate. France and Israel recommend additional doses for vulnerable populations that had reduced immune responses. Tada, T., et al. measured neutralizing activity of sera from individuals vaccinated with the BNT162b2, Moderna mRNA-1273 and Janssen Ad26.COV2.S vaccines against a panel of variants including Alpha, Beta (B.1.351) and Delta. The authors found high cross-neutralization of antibodies induced by 2 doses of the mRNA vaccines but decreased neutralization from antibodies elicited by a single dose of the Ad26.COV2.S vaccine, with the authors suggesting a second dose of the Ad26.COV2.S to increase immune protection from variants. This week, the CDC Advisory Committee on Immunization Practices met to discuss the need for boosters for COVID-19 vaccines, especially for immunocompromised individuals. The advisory committee stated more data was needed before making a formal recommendation.

The situation of the Delta variant has evolved rapidly, and the scientific community is working hard to answer some pressing questions about the vaccines and guidance for the public. Although the recent findings need to be further confirmed, they are hopeful. While waiting for more research to give us further answers, it is clear that COVID-19 vaccines do help, and we desperately need more people to be vaccinated to control the spread. Extra precautions may be needed to give us time to reach herd immunity safely.

Lynn Enquist, Ph.D.

 

 

 

July 16, 2021

By Frederick G. Hayden, M.D., Stuart S Richardson Professor Emeritus of Clinical Virology and Professor Emeritus of Medicine in the Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, Va. Hayden is one of the curators of the registry.

"Casirivimab and imdevimab in patients admitted to hospital with COVID-19 (RECOVERY): a randomised, controlled, open-label, platform trial" by the RECOVERY Collaborative Group, published on medRxiv on June 16, 2021.


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