COVID Vaccine Introduction Results in Decreased Cases, Hospital Admissions and Deaths

Benefits were also observed among adults aged 18 to 49, with adults over 65 seeing the most benefit.

The introduction of the COVID-19 vaccine resulted in a decrease of COVID-19 cases, emergency department visits, hospital admissions, and deaths for older adults, according to the Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report.

CDC investigators compared the rates of COVID-19 cases, emergency department visits, hospital admissions, and deaths during a period prior to vaccine introduction and during a period of time when vaccinations were ramping up in order to determine if those rates would be lowered due to increasing vaccination rates. The investigators compared November 29 to December 12, 2020 (the pre-vaccination period) to April 18 to May 1, 2021 (post-vaccination period) among the oldest age groups, such as those 70 years and over for hospital admissions, and 65 years and older for other measures.

The CDC calculated weekly proportion, rate and rate ratio by age to assess the differences by age for COVID-19 outcomes, they explained, including emergency department visits, hospital admissions, and deaths.

The vaccine was introduced to the U.S. on December 14, 2020 after the FDA employed an Emergency Use Authorization of the Pfizer-BioNTech vaccine. The peak 7-day average of vaccination distribution was 3.3 million doses per day in mid-April, the investigators noted, but decreased to 2.2 million by May 1. At the end of their analysis period, the CDC stated that 82 percent of adults aged over 65 years had received at least 1 vaccine dose. Among those 18 to 49, that number was 42 percent. By the end of the study period, the CDC said that 69 percent of those aged 65 or older and 26 percent of those aged 18 to 49 were fully vaccinated.

Emergency department visits peaked among all age groups during the week of January 3 to 9, 2021, but the study authors found that during the post-vaccination period, emergency department visits were 59 percent lower among all adults compared to the pre-vaccination period.

Rates of COVID-19 hospital admissions also peaked that same week, but post-vaccination rates were 63 percent lower than pre-vaccination rates, the authors learned. COVID-19 admissions were highest among the oldest age groups (70 years and older) but the proportion of adult hospital admissions for COVID-19 dropped from 45 percent pre-vaccine introduction to 27 percent during the post-vaccine period.

Peak mortality from COVID-19 was observed from January 3 to January 16, 2021 among all age groups, the study authors said. However, this decreased through May 1. The mortality rates were highest among the older age groups, but the study authors observed a decrease in the proportion of deaths from this group from 84 percent during the pre-vaccination period to 68 percent during the post-vaccination period. Among 18- to 49-year-olds, the rate of COVID-19 deaths decreased 66 percent, the study authors wrote.

“Despite sufficient vaccine supply and expanding eligibility, administration of COVID-19 vaccines has steadily declined in adults since mid-April 2021,” the study authors concluded. “These results suggest that tailored efforts by state and local jurisdictions to rapidly increase vaccine coverage among all eligible age groups could contribute to further reductions in COVID-19 cases and severe outcomes. Such efforts include effectively communicating the benefits of vaccination, ensuring equitable access and convenience, empowering trusted messengers, including primary health care providers, and engaging communities.”