Lifestyle Health Omicron Is Moving Fast — but a Booster Shot Offers Significant Protection from Infection One study found that while omicron reduces the two-dose vaccine series from Pfizer to just 34% in preventing infection, getting a booster dose brings that protection back up to 75% By Julie Mazziotta Julie Mazziotta Twitter Julie Mazziotta is the Sports Editor at PEOPLE, covering everything from the NFL to tennis to Simone Biles and Tom Brady. She was previously an Associate Editor for the Health vertical for six years, and prior to joining PEOPLE worked at Health Magazine. When not covering professional athletes, Julie spends her time as a (very) amateur athlete, training for marathons, long bike trips and hikes. People Editorial Guidelines Published on December 17, 2021 01:57 PM Share Tweet Pin Email Vaccine. Photo: Getty The new COVID-19 variant omicron is changing the pandemic once again. The strain is the most contagious yet, has more mutations than any before it and seems to evade the previously-effective two-dose vaccines from Pfizer and Moderna. But there is a way to fight off the growing rise in cases, and that's with a booster shot. Researchers tested the variant against the antibodies of people who received the various COVID-19 vaccines and found that they all are less effective with omicron than earlier variants like delta. Johnson & Johnson and AstraZeneca, in particular, made no difference against omicron. But in people who had received a booster shot, they had enough antibodies to fight off omicron from creating an infection. One study from the U.K. found that while omicron reduces the two-dose vaccine series from Pfizer to just 34% effectiveness in preventing infection, getting a booster dose brings that protection back up to 75%. And though the vaccines are less effective in preventing infection with omicron, they are still extremely protective against severe illness that could lead to hospitalization or death. Cases of omicron in vaccinated people have been mild or asymptomatic, with patients recovering within three days, according to a large study from South Africa. After an incubation period of three to four days, patients first reported experiencing a scratchy throat, which then transitions into nasal congestion, a dry cough and muscle aches and pains. RELATED VIDEO: These Celebrities Are Getting the COVID-19 Vaccine to Protect Themselves and Others Health officials have urged Americans to immediately get their booster shots as COVID-19 cases again spike — on Thursday, there were 146,195 new infections in the U.S., an increase of 31% over the last two weeks, according to The New York Times. Dr. Anthony Fauci, the nation's top infectious disease expert, said Wednesday that a booster shot will protect against infection from omicron, and that Pfizer and Moderna do not need to formulate an omicron-specific booster shot. "Our booster vaccine regimens work against omicron," Fauci said, according to The New York Times. "At this point, there is no need for a very specific booster. And so the message remains clear: If you are unvaccinated get vaccinated, and particularly in the arena of omicron if you are fully vaccinated, get your booster shot." As information about the coronavirus pandemic rapidly changes, PEOPLE is committed to providing the most recent data in our coverage. Some of the information in this story may have changed after publication. For the latest on COVID-19, readers are encouraged to use online resources from the CDC, WHO and local public health departments. PEOPLE has partnered with GoFundMe to raise money for the COVID-19 Relief Fund, a GoFundMe.org fundraiser to support everything from frontline responders to families in need, as well as organizations helping communities. For more information or to donate, click here.