Why researchers are sure that the COVID vaccine saved millions of lives

As the world marks the 5-year anniversary of the start of the coronavirus pandemic, one persistent question has been how many lives COVID vaccines helped save.

In January, during his Senate confirmation hearing, Heath and Human Services Secretary Robert Kennedy Jr. was asked by Sen. Bernie Sanders of Vermont whether he believed the vaccines had been effective.

“Was the COVID vaccine successful in saving millions of lives?” Sanders asked.

"I don't know," Kennedy responded.

That runs counter to studies conducted by researchers at Brown University, Yale University, Imperial College London, the World Health Organization and others who have all concluded that, yes, millions more people around the world would have died of COVID-19 were it not for the rollout of vaccines.

And yet, like Kennedy, a growing number of Americans mistakenly believe that COVID vaccines have been responsible for thousands of deaths, according to a 2024 survey by the University of Pennsylvania’s Annenberg Public Policy Center. In the August poll, 28% said they thought COVID vaccines had caused thousands of deaths. In June 2021, that number was 22%.

Yahoo News spoke to Christopher Whaley, a health economist at Brown University, to help clarify how we should view the effectiveness of the shots and the estimated number of lives they’ve saved.

“It’s really hard to think that President Trump’s Operation Warp Speed is anything but that largest public health success in history,” Whaley said. “I think we sometimes lose appreciation for how important and how impactful getting access to vaccines was.”

Whaley has published two studies on the number of lives saved by the COVID vaccines; one of them looked at the impact that the vaccine rollout in December 2020 had on the rate of deaths being recorded.

“In the United States, we found that COVID vaccines averted nearly 140,000 deaths than would have otherwise happened [over the six months studied] if vaccines were not rolled out,” he said.

Calculating excess mortality figures, or the increase in the number of deaths over a given time period versus a comparable period, Whaley then included factors such as the age of a state’s population and how individual states went about distributing the vaccine.

“Alaska, for example, was the first state to reach 20 COVID vaccine doses per 100 adults,’ he said. “Alabama was almost a month later to reach that same threshold in 2021.”

While studies like Whaley’s are estimates, and figures can vary depending on the data set used by researchers, he stressed that the basic approach is scientifically sound and used to calculate outcomes for a variety of things.

“It’s not just COVID vaccines or vaccines in general that we use these types of approaches. As researchers we use them across the board in many aspects of health care,” he said. “The same approach is used to look at what are the health effects of Medicaid expansion and getting access to Medicaid coverage.”

By Whaley’s calculation, COVID vaccines saved 2.4 million lives in 141 countries, when the threat of death from the virus was at its greatest.

“We know that prior to vaccines, COVID was rampant and was leading to many, many deaths,” he said. “Without vaccines, it’s hard to think about a world in which there would have been such an immediate improvement in health and reductions in mortality.”