U.S. regulators on Friday shortened the time that people receiving Moderna’s COVID-19 vaccine must wait for the booster vaccine to five months instead of six months.

Two doses of Moderna vaccine are open to Americans 18 years and older. The US Food and Drug Administration’s decision on Friday means that Moderna recipients are eligible for boosters at least five months after the last injection.

This is in line with the new recommendations for Pfizer vaccinators. Pfizer’s initial vaccination is open to anyone 5 years of age or older. But only Pfizer recipients 12 years of age and older are eligible for booster doses, and US health authorities said earlier this week that they can get the dose five months after the last injection.

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In a statement, Dr. Peter Marks, head of vaccines at the FDA, called vaccination “our best defense against COVID-19” and stated that as the country struggles with the proliferation of highly infectious omicron variants, shortening Stepping up the wait for the vaccine may help.

Two months later, people have urged a booster immunization after receiving a single dose of Johnson & Johnson vaccine.