In just a month’s time in late 2021, COVID-19 vaccination was estimated to prevent more than 50% of expected infections, hospitalizations, and deaths.

Estimating the burden of COVID-19 prevented by vaccination provides evidence for the impact that vaccination can have on public health in reducing the burden of COVID-19 on healthcare systems and preventing deaths, according to Molly Steele, PhD, MSc, MPH, and colleagues. “As more people continue to get vaccinated and receive boosters, additional COVID-19 hospitalizations and deaths are prevented,” Dr. Steele says. “These estimates further enhance the CDC’s understanding of, and communication about, the direct benefits of COVID-19 vaccination.”

For a study published in JAMA Network Open, Dr. Steele and colleagues estimated the number of COVID-19-associated hospitalizations and SARS-CoV-2 infections prevented among vaccinated adults in the United States. “Our goal was to provide clear evidence of the critical public health impact that COVID-19 vaccination has had in limiting COVID-19 infections, preventing hospitalizations, and saving lives,” Dr. Steele says. “Our model was adapted from an established mathematical modeling approach used previously to estimate influenza infections, hospitalizations, and deaths averted by annual influenza vaccination. Different parameters were used in each approach to reflect the different behaviors of the two viruses. In our study, the model used data on the burden of disease, vaccination coverage, and vaccine effectiveness to estimate infections, hospitalizations, and deaths prevented by vaccination.”

Estimates Do Not Account for Benefits to Unvaccinated People

The main finding, according to the study team, is that if more people were vaccinated against COVID-19, there would be further reductions in the numbers of infections, hospitalizations, and deaths. “Additionally, these estimates only account for benefits to those who got vaccinated and do not account for benefits to unvaccinated people through reductions in disease transmission,” Dr. Steele points out. “It is likely that the full impact of COVID vaccination in the US is greater than what we estimated in this study. CDC recommends vaccination with authorized or approved COVID-19 vaccines for everyone aged 5 and older and boosters for all eligible people for the best protection against COVID-19.”

Other key takeaways from the study included:

  • Among vaccinated adults from December 1, 2020-September 30, 2021, the COVID-19 vaccination program was estimated to prevent 27 million infections, 1.6 million hospitalizations, and 235,000 deaths.
  • Those 65 and older and those aged 50-64 belonged to the groups with the highest estimated hospitalizations and deaths prevented.
  • In the adult population, vaccination was estimated to prevent 30% of all expected infections, 33% of all expected hospitalizations, and 34% of all expected deaths (Table).

Clinicians Remain a Strong Influence on Patients’ Vaccine Acceptance

“It’s also important to note that this study is based on data collected up to September 2021 and therefore does not reflect more recent updates related to COVID-19 vaccination, including the authorization of booster doses for most age groups and the expansion of COVID-19 vaccines to children aged 6 months and older,” Dr. Steele adds.

Physicians are urged to make sure their patients are vaccinated and/or up to date on their booster doses, Dr. Steele notes. “As a trusted source of information, clinicians remain a strong influence on patients’ vaccine acceptance. There are several tools and communication resources on the CDC website to help talk about COVID-19 vaccines with your patients, including motivational methods and tips to ease difficult discussions,” she says.

The study team adds that for future modeling studies, there are key areas that could focus on: estimating the impact of COVID-19 vaccination among those younger than 18, indirect benefits of vaccination on transmission of disease, the effect of additional primary or booster doses, and the influence of new variants on overall vaccine impact.