Protection from the Pfizer-BioNTech and Moderna vaccines against serious illness due to COVID-19 declined several months after receiving the second shots, a new government study found, bolstering the case for including booster doses in the standard for full vaccination.
The Centers for Disease Control and Prevention report out Thursday showed that Pfizer and Moderna vaccine efficacy began to fall at least two weeks after a group of 234 veterans at five different healthcare facilities received their second of two shots. Researchers reported that within 14 to 119 days after getting their second shots, protection against severe COVID-19, including hospitalization, fell to about 89% for the Moderna vaccine and 86% for the Pfizer vaccine. The protection afforded by the Moderna and Pfizer vaccines in those veterans dropped to 86% and 75%, respectively, at least 120 days following the second round of shots.
Researchers behind the report said their findings supported the need for third doses of the vaccines, also referred to as “boosters.”
"These findings from a cohort of older, hospitalized veterans with high prevalences of underlying conditions suggest the importance of booster doses to help maintain long-term protection against severe COVID-19," the authors of the report said.
The CDC maintains that a person is fully vaccinated after two weeks have passed since getting a second shot.
The Biden administration will consider updating that standard definition “literally on a daily basis,” according to Dr. Anthony Fauci, President Joe Biden’s chief medical officer. Until then, the definition of “fully vaccinated” remains murky and can vary by state. For instance, Connecticut Gov. Ned Lamont said last month that anyone who got a COVID-19 vaccine more than six months ago cannot be considered fully vaccinated until getting a booster. Meanwhile, the Michigan government said last month that it would abide by the CDC’s current definition.
OMICRON FEARS BOOSTING VACCINATIONS
To date, more than 60% of people in the United States have been fully vaccinated, and CDC tracking found that nearly 49 million adults have received a booster dose. Concern over the new and little-understood omicron variant has driven an uptick in daily vaccinations. The U.S. remains far behind some other developed countries, such as Portugal and Singapore, where nearly 88% of the population is fully vaccinated.