Unvaccinated people had 13.9 and 53.2 times the risks for infection and COVID-19-associated death, respectively, compared with fully vaccinated people who received a booster dose of a COVID 19 vaccine, and 4.0 and 12.7 times the risks compared with fully vaccinated people without booster doses, according to the Centers for Disease Control and Prevention (CDC) in a new study released in Morbidity and Mortality Weekly Report.
That data was specifically from October 2021-November 2021 as part of a study based on 25 jurisdictions.
Overall, data for the study was collected from April 4-December 25, 2021, and included a total of 6,812,040 COVID-19 cases among unvaccinated people and 2,866,517 cases among fully vaccinated people 18 years or older; 94,640 and 22,567 COVID-19-associated deaths among unvaccinated and fully vaccinated people, respectively, were reported by December 4. Average weekly, age-standardized rates of cases and deaths (events per 100,000 population) were higher during periods of Delta predominance and Omicron emergence than during pre-Delta and Delta emergence periods and were consistently higher in all periods among unvaccinated people.
Rates of COVID-19 cases were lowest among fully vaccinated people with a booster dose, compared with fully vaccinated people without a booster dose, and much lower than rates among unvaccinated people during October-November (25.0, 87.7, and 347.8 per 100,000 population, respectively) and December 2021 (148.6, 254.8, and 725.6 per 100,000 population, respectively) Similar trends were noted for differences in the mortality rates among these three groups (0.1, 0.6, and 7.8 per 100,000 population, respectively) during October-November, the CDC reported.
The added benefits of booster doses were especially prominent among people aged 50-64 and people 65 years of age and older.
To assess the impact of full vaccination with additional and booster doses (booster doses), researchers estimated case and death rates and incidence rate ratios (IRRs) among unvaccinated and fully vaccinated adults by receipt of booster doses during pre-Delta (April-May 2021), Delta emergence (June 2021), Delta predominance (July-November 2021), and Omicron emergence (December 2021) periods in the United States.
Weekly COVID-19 cases (April 4–December 25, 2021) and associated deaths (April 4–December 4, 2021) by vaccination status, including additional and booster doses starting October 3, were reported from 25 state and local health departments that routinely link case surveillance to vaccination data from immunization registries.
