In one investigation, published January 21 in the Centers for Disease Control and Prevention (CDC) Morbidity and Mortality Weekly Report (MMWR), analysis of more than 220,000 visits to emergency or urgent care departments between August 2021 and January 2022 found that receipt of a third vaccine dose of Pfizer or Moderna was highly effective at preventing COVID-associated emergency and urgent care encounters (94 percent and 82 percent, respectively) and preventing COVID-associated hospitalizations (94 percent and 90 percent, respectively). A second report, published in the same MMWR issue and based on data from 25 U.S. jurisdictions between April 4 and December 25 (when the delta strain dominated but omicron was gaining ground), indicated that protection against infection and death were higher among booster vaccine dose recipients, and especially among persons ages 50 and older. The study highlighted that adults who were unvaccinated had a 5 times higher risk of infection compared with adults who were fully vaccinated with a booster. A third paper, published January 21 in JAMA, looked at 13,098 omicron and 10,293 delta infections and suggested that receipt of three doses of mRNA vaccine, relative to being unvaccinated and to receipt of two doses, was associated with safeguarding against both the omicron and delta variants. The study authors warned, however, that vaccines overall offered less defense against omicron. RELATED: Get Up-to-Date COVID-19 News in the Daily Coronavirus Alert “These reports add more evidence to the importance of being up-to-date with COVID vaccinations. That means getting primary series, and boosted when eligible to protect against severe COVID 19,” said Rochelle Walensky, MD, MPH, director of the CDC, at a White House briefing Friday. William Schaffner, MD, an infectious disease specialist and professor of preventive medicine and health policy at the Vanderbilt University School of Medicine in Nashville, Tennessee, stressed that because these three rigorous studies provide strong evidence that a booster dose is necessary to provide reliable protection against severe COVID-19 disease that requires hospitalization, “The time has come to redefine ‘fully vaccinated’ as including the booster dose.” Latest CDC data shows that three-quarters of the U.S. population have now received at least one vaccine dose and 63.4 percent have received two, per the University of Minnesota on January 21. Just 4 out of 10 people who have been received at least two doses, however, have also received a booster jab. “That rate is much too low,” said Dr. Schaffner. “Redefining ‘fully vaccinated’ to include the booster dose will motivate many persons to get boosted. Fortunately, there are ample vaccine supplies available, but vaccine in the refrigerator cannot prevent hospitalization — it has to be put into arms!” Scientists had been investigating the possibility that a fourth booster dose may be coming, noted The New York Times on January 18, but research thus far suggests it might not offer much additional protection. “Fourth doses are not being considered currently by the CDC’s Advisory Committee on Immunization Practices (ACIP),” says Schaffner. Scientists are also working on an omicron-specific vaccine, per CNBC on January 10. “If the reduction in omicron cases across the United States continues, there may not be a need for an omicron booster, but it would be good to have it on the shelf, ready for use, if necessary,” says Schaffner.
