Covid-19 vaccines helped alter the trajectory of the pandemic significantly over the past year, preventing catastrophic numbers of cases, hospitalizations, and deaths, according to a new model by the Commonwealth Fund.

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The profound impact of Covid-19 vaccines on the pandemic

Over the course of the pandemic, more than 5 million people in the world—and almost 900,000 people in the United States alone—have died from Covid-19. But while much attention has been focused on the pandemic's persistence, particularly as new, more transmissible coronavirus variants emerge, there have also been positive developments—namely, the Covid-19 vaccines.

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According to Vox, the current Covid-19 vaccines were developed faster than any new vaccine in history, and models from several organizations and researchers show that the vaccines played a significant role in reducing cases, hospitalizations, and deaths over the course of the last year.

According to a study published in JAMA Network Open, Covid-19 vaccines helped avert 14 million cases, 1.1 million hospitalizations, and more than 240,000 deaths between Dec. 12, 2020, and June 30, 2021—before the delta variant surge. "[The impact] was larger than we would've expected," said Meagan Fitzpatrick, an infectious disease modeler at the University of Maryland and one of the study's authors.

Similarly, a model created by Sumedha Gupta, a health policy economist at Indiana University-Purdue University Indianapolis, found that by May 9, 2021—or less than six months after vaccines became available—140,000 Covid-19 deaths were prevented. In particular, Gupta found that the most vulnerable populations, including the elderly, the immunocompromised, and those with preexisting conditions, benefited the most from vaccinations at this time, although they also protected unvaccinated individuals by slowing down viral transmission.

The timing of the United States' mass-vaccination campaign was also fortuitous, experts told Vox, kicking in just as the country was facing a new surge in cases. "Not only did our vaccination program really suppress the ongoing surge ... but it also helped avoid a later spring wave that would have happened with variant emergence," Fitzpatrick said. "I think the main takeaway is really focusing on speed and not just coverage. The emphasis that we had on getting the vaccines out fast ... was the right impulse."

In addition, a recent study from the Commonwealth Fund suggests that the Covid-19 vaccines' impact has only grown over time. For the study, researchers created a model to analyze the effects of the U.S. vaccination program between Dec. 12, 2020, and Nov. 30, 2021. Overall, they estimated that Covid-19 vaccines helped prevent over 35 million cases, 10.3 million hospitalizations, and approximately 1.1 million deaths during that time period. Without vaccines, the number of Covid-19 hospitalizations and deaths in 2021 would have been approximately 4.9 and 3.2 times higher, respectively.

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According to the researchers, the majority of these averted hospitalizations and deaths would have occurred during the late summer and early autumn of 2021 when the delta variant was surging in southern states and beginning to spread nationwide. The daily peak in deaths would have also reached 21,000 per day, much higher than the country's previous peak of 4,000 a day in January 2021.

Vaccines shouldn't be the only tool against the pandemic

Currently, around a quarter of the U.S. population, or more than 80 million people, are still unvaccinated, Vox reports, leaving them at higher risk of severe Covid-19 outcomes. According to CDC, unvaccinated individuals are 15 times more likely to die from Covid-19 than those who are vaccinated.

"We're really leaving [the] benefits [of vaccination] on the table," Gupta said.

However, according to experts, despite the promise of vaccinations, vaccinations alone will not be enough to end the pandemic. Vaccine immunity wanes over time, and the coronavirus may be evolving in ways that let it evade immunity more easily, such as with the omicron variant.

According to Vox, the United States has typically overlooked other, non-pharmaceutical interventions in favor of encouraging vaccination, much to its detriment now. For example, the federal government only just recently began distributing free rapid Covid-19 tests and medical-grade face masks for all Americans. Public gatherings have also largely resumed across the country, and many mask mandates have been lifted, even in areas of high viral transmission.

"It really was a problem of too much hubris, that (many believed) vaccines would be the only thing we needed," Fitzpatrick said. "It's not 'either/or,' it's 'both-and.'" (Irfan, Vox, 1/27; Schneider et al., Commonwealth Fund, 12/14/21)