U.S. biotechnology firm Moderna Inc. said Monday that a third shot of its coronavirus vaccine has been shown in a laboratory test to significantly increase antibodies that would fight off the highly transmissible Omicron variant.
The announcement came as the United States is seeing another surge in coronavirus cases, with Omicron accounting for about two-thirds of new infections last week, according to the latest data from the Centers for Disease Control and Prevention.
Preliminary data from lab tests in the Moderna study showed that a two-dose course of the vaccine, with each shot containing 100 micrograms, provided only low levels of antibodies. But the currently authorized 50-microgram booster increased the antibody levels around 37-fold 29 days after inoculation.
Given the strength of the vaccine and the speed at which the Omicron variant is spreading, Moderna's "first line of defense against Omicron will be a booster dose," the company said.
The study also showed that a 100-microgram booster shot increased antibody levels approximately 83-fold, and was found to be "generally safe," it said.
The side effects seven days after receiving a booster were also "generally comparable to those seen after the two-dose primary series," but adverse reactions were seen slightly more frequently following the 100-microgram shot relative to the 50-microgram dose.
Moderna said it will continue to develop an Omicron-specific vaccine, given the "long-term threat" demonstrated by the new variant's immune escape, expecting to advance into clinical trials in early 2022.
U.S. pharmaceutical giant Pfizer Inc. has also said that a third shot of its COVID-19 vaccine can increase antibodies 25-fold, providing a similarly high level of protection as observed with the two-dose series before the emergence of the new variant.
While the U.S. government has continued to campaign for people to get inoculated against the novel coronavirus, around 39 percent of the country's total population has yet to be fully vaccinated, according to CDC data.
Currently, the seven-day rolling average of cases is about 133,000 per day, according to the CDC. Its data also showed that Omicron made up 73.2 percent of new cases in the week through Saturday, a nearly six-fold rise from the week before.
The White House, meanwhile, announced that President Joe Biden was in close contact on Friday with a mid-level staff member, who received a positive result for a COVID-19 test on Monday.
The 79-year-old president, who is fully vaccinated and also boosted, tested negative after being notified of the staff member's positive test. The person had spent some 30 minutes in proximity to the president on Air Force One on the way from South Carolina to Pennsylvania.
The staff member, who was also fully vaccinated and boosted, tested negative prior to boarding the plane. The person did not begin to experience symptoms until Sunday and was tested on Monday, according to the White House.
As concerns over the Omicron variant grow, Washington Mayor Muriel Bowser said Monday she is declaring a state of emergency to better prepare for outbreaks and is reinstating the indoor mask mandate in the nation's capital, which was lifted in November.
The mask mandate will be introduced on Tuesday at 6 a.m. and remain in place through Jan. 31 at 6 a.m.
