COVID-19 Vaccine Effectiveness Wanes Against Omicron

A new study funded by the U.K. Health Security Agency and published as an Original Article by the New England Journal of Medicine on Mar 2, 2022, concluded by stating 'Primary immunization with two doses of COVID-19 vaccine provided limited protection against symptomatic disease caused by the SARS-CoV-2 virus variant known as Omicron.'

And a Cominraty (BNT162b2) or SpikeVax (mRNA-1273) booster after either the AstraZeneca (ChAdOx1 nCoV-19) or Comirnaty primary course substantially increased protection, but that protection waned over a short period of time.

The researchers used data from the National Immunization Management System from Nov 27, 2021, to Jan 12, 2022, to estimate COVID-19 vaccine effectiveness (VE) against symptomatic illness caused by the Omicron and Delta variants.

VE was higher against Delta throughout the study than Omicron for all combinations of the primary vaccine series and booster doses. 

These researchers could not determine VE against severe illness using this study's test-negative, case-control design because the number of severe Omicron cases leading to hospitalization was limited, and the natural lag between infections and poor outcomes was too long.

'Our findings indicate that vaccine effectiveness against symptomatic disease caused by the omicron variant is substantially lower than with the Delta variant,' concluded these researchers.

Dr. Lopez Bernal can be contacted at [email protected]. No industry conflicts of interest were disclosed.