The definition of what it means to be fully vaccinated against COVID-19 may shift in the future, according to a Regenstrief Institute scientist who participated in a study that looked at whether two vaccine doses offer sufficient protection against omicron.
The national study looked at more than 300,000 patients who either visited the hospital emergency room or who were hospitalized for COVID-19 between August 2021 and January.
While two doses of either the Pfizer BioNTech or Moderna mRNA vaccine protected against the delta variant, the level of effectiveness declined precipitously once omicron entered the picture, said Dr. Shaun Grannis, co-author of the Centers for Disease Control and Prevention study and vice president for data and analytics at Regenstrief Institute.
Two doses of vaccine did a decent job of protecting against the delta variant. The double dose was 86% effective at preventing against an emergency department visit within the first six months and 76% effective after that. Adding a booster to the equation brought effectiveness up to 94%. Similarly, two doses offered 90% protection against hospitalization with delta for the first six months, 81% after that versus 94% after the booster.
The gap in effectiveness between two doses and a third widened considerably, however, with omicron. Two doses were 52% effective in protecting against emergency room visits for omicron in the first six months and then dropped to 38%. Vaccine effectiveness rose to 82% once a booster was added to the mix.
There's better news at how the booster protects against serious illness. When it came to preventing hospitalizations from omicron, protection went from 81% within the first six months after two doses to 57% and then bounced up to 90%.
Given these results, two doses may no longer be considered sufficient protection against COVID-19, said Grannis, also a professor of family medicine at Indiana University School of Medicine.
“We are starting to see a shift in language from fully vaccinated to being up to date on COVID vaccine,” he said. “Additional vaccines might be needed in the future.”
Ideally after the omicron wave passes, he said, COVID-19 will become another flu. But the arrival of a new variant could change that. In either case, he said, it’s likely that in order to enjoy the fullest protection from whatever COVID-19 throws at us, we will need annual booster shots.
However, Indiana residents have not embraced the booster shots. While 3.6 million Hoosiers are considered fully vaccinated at this point, according to the state’s vaccine dashboard, only 1.6 million have had a booster dose.
COVID-19 is surging in Indiana. The state set a new single day record for cases reported Friday with 17,684.
The study’s results may help persuade people who have received two doses of vaccine that they should get the booster, Grannis said, noting
“We still have a lot of room to move the needle on that,” Grannis said. “I hope this evidence is clear enough.”
To make an appointment to get vaccinated or find a booster, visit ourshot.in.gov or call 211. Many sites also accept walk-ins.
This article originally appeared on Indianapolis Star: CDC study: COVID vaccine booster needed to protect against omicron