Exactly five years ago today, after more than 118,000 cases and more than 4,200 deaths across 114 countries had been recorded, the World Health Organization declared the novel coronavirus a pandemic.
With the virus spreading rapidly around the world, the need for a vaccine was desperate — but the prior record for the fastest development of a new vaccine to a new virus was four years.
Yet vaccines using the new technology of mRNA were developed by Moderna and Pfizer/BioNTech in a matter of months. mRNA — or messenger RNA, a kind of genetic script — prompted cells to produce special proteins that would allow the body to develop an immunity to the novel coronavirus.
Scientists, who are usually not prone to crediting divine intervention, called the mRNA vaccines a miracle.
Four in five Americans received at least one dose; when we remember less than half of Americans get their flu shot each year, the high uptake of mRNA shots signaled a willingness from the US public to trust this novel technology. And there was optimism that mRNA technology could be used to make better vaccines for other diseases.
Now, that embrace is fraying.
Even as the vaccines were actively pulling the US out of the pandemic, skepticism about mRNA technology was rising. Robert F. Kennedy Jr., still a private citizen at the time and one of the country's most vocal vaccine skeptics, urged the first Trump administration to pull the shots.
Now the nation's top health official, Kennedy is reevaluating the US Health and Human Services's contract with Moderna, which is developing mRNA flu vaccines targeting strains with high pandemic potential.
With Kennedy at the helm of HHS, scientists and public health experts worry that new major breakthroughs are in peril — just a few years after mRNA proved its value.
Kennedy was just one of many influencers and politicians who turned against the Covid vaccines. By autumn 2021, less than a year after the vaccines' debut, anti-vaccine communities were thriving, constructing an alternative narrative of the pandemic in which the disease itself was not actually that serious but the vaccine could alter your DNA or plant a chip in your body.
As these conspiracy theories grew in popularity, uptake for the booster shots plummeted; in November 2023, only 15 percent of Americans received the latest version of the vaccines.
In January 2025, a KFF poll found four in 10 Republicans said it was "probably" or "definitely" true that more people had died from the Covid-19 vaccines than from Covid-19 itself, which represented a 15-point increase from a July 2023 survey.
Scientists have documented at most a few dozen deaths attributable to the vaccines worldwide after billions of doses were administered, and population-level analyses have detected no meaningful increase in mortality after the vaccines were introduced.
But those facts are too often ignored.
Thanks to a growing climate of vaccine — especially mRNA vaccine — skepticism, we are at risk of losing out on medical innovations. Scientists are working on a universal flu shot and respiratory virus vaccines, and are showing promising results with cancer vaccines.
Under the Trump administration, that research could be under threat. And even if breakthroughs do happen, the question is whether, after our collective experiences of the past five years, Americans will want them.
