Unvaccinated 5X more likely to get omicron than those boosted, CDC reports

A tray of prepared needles for Moderna's vaccine.

Real-world data on the effectiveness of COVID-19 booster doses is now rolling in, and it is only looking up for boosters.

Two of the studies were published in the CDC's Morbidity and Mortality Weekly Report and the other was published in the Journal of the American Medical Association.

The MMWR looked at the vaccination status of 10 million COVID-19 cases from 25 state and local health departments. CDC scientists and health officials compared weekly rates of COVID-19 infections between unvaccinated people, fully vaccineed people, and people who were boosted. Unvaccinated people were three times more likely to report a case of COVID-19 than people fully vaccined. Unvaccinated people were five times more likely to report a case than people who had been fully vaccined.

The study supported this finding. In that work, CDC scientists looked at the test results from around the country. The analysis concluded that people were more likely to be boosted than unvaccinated people because omicron infections were less likely to occur in fully vaccineed people.

Both studies noted a drop in vaccine effectiveness against omicron. Researchers looked at cases from October to November when the delta was raging. They found that people who were unvaccinated were four times more likely to be diagnosed with delta late in the year than people who were fully vaccined.

The vaccine is effective against infections.

In the second MMWR study, CDC scientists found that booster doses appear to restore protection against serious disease and hospitalization back to the levels of the 1960's. A multi-state analysis looked at 223,000 patient visits to emergency rooms or urgent care centers for COVID-19, as well as 88,000 hospitalizations, all between last August and earlier this month.


The effectiveness of two doses against emergency room and urgent care visits started out at 86 percent, but fell to 76 percent as people reached beyond six months after their second vaccine, and was pushed back up to 94 percent after a booster dose. The two-dose effectiveness against emergency room and urgent care visits started out at a dismal 52 percent, fell to 38 percent with waning protection, and was boosted back to 82 percent after a booster.

The vaccine is effective against emergency room and urgent care visits.

The effectiveness of two doses began at 90 percent, but fell to 81 percent as protection waned, and then rose to 94 percent after a booster. The two-dose effectiveness started at 81 percent, fell to 57 percent with waning, and then rose to 90 percent after a booster.

Vaccine effectiveness against hospitalization.

CDC Director Rochelle Walensky said in a White House Press briefing Friday that the data highlight two important points. Those who are unvaccinated are at higher risk for infections. Those who are up to date with their vaccinations are the most protected against infections and hospitalization with the omicron variant.

Only 63 percent of the US population is fully vaccineed, and tens of millions of people who are eligible for a booster have not gotten one. "I urge all who are eligible to get their booster shot as soon as possible," Walensky said.