Three new studies from the U.S. Centers for Disease Control and Prevention show that booster shots provide a significant bump in protection against the highly transmissible omicron variant of COVID-19.
“Taken together, these data highlight two important points,” said CDC Director Rochelle Walensky during a White House press briefing. “First, those who remain unvaccinated are at significantly higher risk for infection and severe COVID-19 disease. Second, protection against infection and hospitalization with the omicron variant is highest for those who are up to date with their vaccination, meaning those who are boosted when they are eligible.
“There are still millions of people who are eligible for a booster dose and have not yet received one. As we continue to face the omicron variant, representing over 99% of infections in the United States today, I urge all who are eligible to get their booster shot to get it as soon as possible.”
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Two of the studies were published Thursday in the CDC’s Morbidity and Mortality Weekly Report.
Protection against hospitalization, emergency visits
In one study, researchers evaluated hospitalizations and visits to emergency rooms and urgent care facilities in 10 states from Aug. 26, 2021 to Jan. 5, 2022.
Protection against hospitalization for individuals who’d received two doses of the vaccine within the last six months was 81%. It dropped to 57% after six months. Protection for individuals who’d received their booster increased to 90%, according to the study.
Protection against visits to emergency departments or urgent care clinics was 52%, 38%, and 82%, respectively.
Protection against infection, death
A second study analyzed COVID-19 cases and deaths in 25 states between April 4 and Dec. 25, 2021.
It showed there were fewer infections and deaths among individuals who’d received three shots compared to those who’d only received two — and signficantly fewer infections when compared to individuals who were unvaccinated.
Data from December showed that among unvaccinated individuals there were 726 cases per 100,000 people on average per week. For those who had received two doses of a COVID-19 vaccine, the average was 255 per 100,000. For those who had received a booster, it was 149 per 100,000.
The jump in protection offered by boosters — against infection and death from the delta variant and against infection from omicron — was the most significant among individuals 50 and older.
Because of reporting lags, the influence of the omicron variant on COVID-19–associated deaths by vaccination status in December could not be evaluated. However, in October and November, there were 7.8 deaths of unvaccinated individuals per 100,000, compared to 0.6 deaths among individuals who had received two doses of the vaccine and 0.1 among individuals who had received a booster shot.
Protection against symptomatic infection
A third study published in the Journal of the American Medical Association found that individuals who had received three shots of a COVID-19 vaccine, compared to those who had only received two or were unvaccinated, had a higher level of protection against symptomatic infection from the virus.
CDC researchers analyzed 70,155 tests from adults with COVID-19 symptoms. The study found that, among the individuals who had contracted omicron, 18.6% had received three vaccine doses, compared to 55% who had received two.
Julia Hunter is the engagement editor for Hoptown Chronicle. Reach her at julia@hoptownchronicle.org.
