How many serious and deadly infections have been prevented?

Today, December 13, marks 2 years since the first American patients received a Covid-19 vaccine.

The first American to be injected with COVID-19 outside of a clinical trial was intensive care nurse Sandra Lindsay. “It didn’t feel any different from taking any other vaccine,” Lindsay said at the time.

Of course, the COVID-19 vaccine was different because of its potential to help end the worst of the global pandemic. In the 2 years since the first doses were rolled out, the United States has administered over 655 million COVID-19 vaccines. The Commonwealth Fund estimates 80% of Americans have received at least 1 injection of COVID-19.

Commonwealth Fund investigators conducted a study to simulate disease transmission if there had been no COVID-19 vaccines. They concluded that the US COVID-19 vaccination program prevented 120 million additional COVID-19 infections, as well as more than 18.5 million hospitalizations and 3.2 million deaths.

Using reported COVID-19 incidence per 100,000 Americans, investigators estimated severe and fatal illness in a scenario without COVID-19 vaccines. They used a computer model of disease transmission to calculate hospitalizations and deaths averted from December 2020 to November 2022. Investigators included demographic data and risk factors stratified by age to ensure the best estimate of immunological differences in vaccination and infection.

Since December 12, 2020, the United States has reported 82 million infections, 4.8 million hospitalizations and 798,000 deaths. With vaccinations, investigators calculated that the United States would have had 1.5 times more infections, 3.8 times more hospitalizations and 4.1 times more deaths.

Vaccines have reduced both the incidence of COVID-19 and the severity of symptoms. So, in addition to averting additional infections, illnesses, and deaths, the COVID-19 vaccination program likely saved US$1.25 trillion in medical costs.

“The impact of the vaccination program is more remarkable given the challenges posed by the multiple variants that have emerged,” the study authors wrote. Indeed, the constantly mutating Omicron variant has proven to be exceptionally contagious and evasive. The United States Centers for Disease Control and Prevention (CDC) currently believes the Omicron BQ.1.1 and BQ.1 variants are responsible for a combined 68% of COVID-19 infections.

Even with the relentless mutations of COVID-19, vaccines have remained effective. Now, bivalent COVID-19 vaccines offer even higher levels of protection against these emerging strains. Notably, COVID-19 vaccines have also helped keep children in school.

Effectively combating COVID-19 infections is proving especially vital now, as we witness unprecedented cases of flu and RSV. Moving forward, the investigators concluded, “accelerating uptake of the new booster will be fundamental to avoiding future hospitalizations and deaths.”