Experts estimate that the three variants of concern now account for more than half of Massachusetts cases.
Three highly infectious COVID-19 variants are now estimated to account for more than half of all infections in Massachusetts, expert witnesses said during a state legislative hearing Tuesday.
Dr. Bronwyn MacInnis, the director of pathogen genomic surveillance at the Broad Institute of MIT and Harvard, testified to lawmakers that, as of Monday night, the three so-called “variants of concern,” which are more transmissible than initial versions of the virus, had risen to make up more than 50 percent of the statewide sampling of cases examined by the Cambridge research center.
“The horse is out of the gate,” MacInnis said, calling the threshold “significant” if not “terribly surprising.”
Federal data shows that the B.1.1.7. variant, which originated in the United Kingdom, is now by far the most common version of COVID-19 in the United States. Massachusetts is also the state with the most identified cases of the P.1 variant, which was first detected in Brazil, due to a recent cluster of infections on Cape Cod and the state’s relatively robust sequencing efforts.
In Massachusetts, federal data says there have been a total of 1,100 cases of the B.1.1.7 variant, 102 cases of the P.1 variant, and 12 cases of the B.1.351 variant, which originated in South Africa. But those numbers come from a tiny slice of overall cases; MacInnis says the state is currently sequencing roughly 1.4 percent of all cases, slightly above the national average of about 1 percent.
While concerned by the trends, experts also noted that public health data suggests the rise — and most adverse consequences — of the variants have been at least somewhat blunted by the vaccinations.
Dr. Paul Biddinger, the head of emergency preparedness at Massachusetts General Hospital and chair of the state’s COVID-19 vaccine advisory group, noted that deaths due to the disease have largely continued to trend downward since the beginning of February, even as the decline in infections and hospitalizations leveled off and slightly increased in late March. Biddinger attributed the divergent trends to the rollout of the vaccines, which prioritized older residents and other individuals who are more vulnerable to severe illness due to COVID-19. State officials say that more than 80 percent of residents over the age of 75, who continue to account for a vastly disproportionate number of the state’s COVID-19 deaths, have been vaccinated.