Since Covid-19 vaccines became available in 2020, they have prevented over 18.5 million hospitalizations and 3.2 million deaths, saving the U.S. health care system roughly $1.15 trillion, according to a study published Tuesday by the Commonwealth Fund.

How the Covid-19 vaccine changed the pandemic

For the study, researchers at the Commonwealth Fund adapted their Covid-19 model to include the decline of naturally acquired and vaccine-acquired immunity, as well as booster vaccination. They also incorporated the characteristics of the original SARS-CoV-2 strain and five variants, including iota, alpha, gamma, delta, and omicron.

In addition, the model accounted for population demographics, prevalence of comorbidities, a contact network that determined changes in pandemic restrictions and mobility patterns, and age-specific risks of severe health outcomes from Covid-19. The model also included data on daily vaccine doses administered and the age-based availability of the vaccine.

To evaluate the impact of the Covid-19 vaccine rollout, the researchers simulated the pandemic's trajectory without the vaccine. Then, they compared the simulated outcomes of total infections, hospitalizations, and deaths to their model, which measured the actual pandemic and vaccinations that occurred in the United States between Dec. 12, 2020, and Nov. 30, 2022.

According to the report, in the two years since the Covid-19 vaccine became available in the United States, over 655 million doses have been administered, with around 80% of the population having received at least one dose.

From December 2020 through November 2022, their estimates projected that the Covid-19 vaccination program prevented over 18.5 million additional hospitalizations and 3.2 million additional deaths. Without the vaccine, their estimates suggested there would have been around 120 million additional Covid-19 infections. Notably, the study found that the vaccination program saved the United States around $1.15 trillion in medical costs.

"This extraordinary achievement was made possible through sustained funding and policymaking that made vaccines available to all Americans," said Alison Galvani, the founding director of the Yale Center for Infectious Disease Modeling and Analysis and a co-author of the study. "Moving forward, we need to [be] accelerating the uptake of the new booster, which is fundamental to averting additional hospitalizations, deaths and school absenteeism." 

The US health system is still strained

While many providers agree that the U.S. health care system would be in worse shape if Covid-19 vaccines were not available as early as they were, many hospitals around the country are currently at full capacity as they struggle address a "tripledemic" of Covid-19, influenza, and respiratory syncytial virus (RSV) amid ongoing workforce shortages.

In September, HHS announced that coverage of Covid-19 vaccines and treatments would shift to the commercial market as early as January 2023—a move some experts say could strain the health care system even further. Once federal purchasing ends, distributors in the commercial market will purchase vaccines and distribute them to health care facilities, including hospitals, physician's offices, and pharmacies.

In the private sector, pricing "will become an issue for an entity that thus far hasn't been that directly involved, which is insurers and commercial plans," said Healthcare Distribution Alliance CEO Chip Davis.

While insurers will be required to pay for Covid-19 vaccines without charging patients copays or out-of-pocket costs, they will likely pass on the costs by charging higher premiums, Modern Healthcare reports.

In addition, next year, 18 million Medicaid beneficiaries will lose coverage after the Covid-19 public health emergency ends, and around 4 million people will become uninsured, according to estimates from Robert Wood Johnson Foundation.

As more Americans lose health care coverage and insurance companies' costs to cover vaccines continues to increase, insurers and health systems may push those costs onto patients, which could further impact vaccination rates, according to Galvani.

"Curbing hospitalization rates is particularly important amidst the strain on the healthcare system caused by the flu and RSV, and COVID vaccination helps preserve hospital resources," Galvani said. "But I am worried that if people have to pay more out of pocket because they are uninsured or have high deductibles and copays, that is not going to help with the rate of uptake of the new booster." (Kacik, Modern Healthcare, 12/13; Fitzpatrick et al., Commonwealth Fund, 12/13)