Moderna COVID-19 vaccine protection lasts at least 6 months, study finds

Extended interview: Expert explains how COVID-19 vaccines work and side effects after shots

Dr. Williams Moss, an epidemiologist and executive director of the International Vaccine Access Center at Johns Hopkins, explains how mRNA vaccines by Pfizer and Moderna work and why side effects are more likely after the 2nd dose.

BOSTON - New research suggests the Moderna vaccine against COVID-19 offers protection for at least six months.

Findings published Tuesday in the New England Journal of Medicine echo what Pfizer and its German partner, BioNTech, said last week about their vaccine, which works in a similar way.

The study of Moderna’s vaccine followed 33 healthy adult participants and found "antibody activity remained high" across all age groups six months after the second dose, researchers said.

The team was led by Nicole Doria-Rose of the U.S. National Institute of Allergy and Infectious Diseases (NIAID). The Moderna vaccine was co-developed by Moderna, Inc., a biotechnology company based in Massachusetts, and the NIAID.

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FILE - A woman is given a dose of Moderna COVID-19 vaccine on April 1, 2021, in Reading, Pennsylvania. (Photo by Ben Hasty/MediaNews Group/Reading Eagle via Getty Images)

Researchers said ongoing studies are monitoring the vaccine’s immune response beyond six months. Both Moderna and Pfizer have said they are also working to update their vaccines, or possibly design a booster shot, in case they’re needed against troubling new variants — or versions of the coronavirus — that are circulating.

On Thursday, Pfizer updated results from the ongoing late-stage study of more than 44,000 volunteers and also confirmed the two-dose vaccine continues to be effective against COVID-19 up to six months later.

Both Moderna and Pfizer’s mRNA vaccines underwent large clinical trials that led to the vaccines’ use in the U.S. The studies were done before new variants had emerged and started to spread.

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Meanwhile, both companies have completed enrollment for studies of children ages 12 and older and are expected to release the data in the months ahead. Both are also now studying their shots in children under 12 — including babies as young as 6 months.

Johnson & Johnson, a third vaccine currently being administered in the U.S., also recently began testing its shot in older children and teenagers.

In a separate report published Tuesday in the medical journal, scientists measured antibodies that can block the virus. Researchers looked at 50 people who had been given the Sinopharm or Sinovac vaccines that were developed in China using a different technology than Moderna and Pfizer’s mRNA vaccines.

Many showed total or partial loss of effectiveness against a virus variant first detected in South Africa. The Sinopharm and Sinovac vaccines still seemed to protect against a variant first found in the United Kingdom that is now rapidly spreading in the United States and elsewhere.

This story was reported from Cincinnati. The Associated Press contributed.