Moderna’s Covid-19 vaccine protects people for at least six months and likely longer — even against new variants, researchers reported Thursday.
Protection against the Delta variant, now dominant across the US, barely waned, the National Institutes of Health-led team found. The team will continue to look for evidence of protection beyond six months.
“High levels of binding antibodies recognizing all tested variants, including B.1.351 (Beta) and B.1.617.2 (Delta), were maintained in all subjects over this time period,” immunologist Nicole Doria-Rose and colleagues at the NIH’s National Institute of Allergy and Infectious Diseases wrote in their report, published in the journal Science.
They tested blood from 24 fully vaccinated volunteers at several time points — four weeks after the first dose of the Moderna vaccine, and then at three points after they were considered fully vaccinated with two doses — up to six months out.
“At the peak of response to the second vaccine dose, all individuals had responses to all variants,” the team wrote. Two weeks after the second dose of Moderna’s vaccine, all the blood samples neutralized all of the variants, they found.
They included all the most common or worrying variants in the test: B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), B.1.429 (Epsilon), B.1.526 (Iota) and B.1.617.2 (Delta).
The variant most likely to elude immune protection was Beta, or B.1.351 — the variant first seen in South Africa. Six months after the second dose, just over half of blood samples maintained antibodies that fully neutralized Beta variant samples. But at six months, 96% of samples had a full antibody response against the Delta variant, the team found.