The drugmakers Moderna and Pfizer buoyed hopes for an end to the coronavirus pandemic when they announced this month that their vaccines were 94.5 percent (Moderna) and 90 percent (Pfizer) effective at preventing Covid-19, based on preliminary results from ongoing clinical trials. Neither vaccine produced any serious safety concerns.
Pfizer’s and Moderna’s data were analyzed by independent experts, though their findings were published in news releases, not peer-reviewed scientific journals, so the results are not yet considered conclusive. But if the numbers hold steady through the end of the trials, these vaccines would be among some of the most effective ever created.
What would that mean for the future of the pandemic and vaccine science, and what obstacles still stand in the way of getting shots in people’s arms? Here’s what people are saying.
An unexpected breakthrough
The clinical success that Pfizer and Moderna are reporting was not supposed to happen. The average influenza vaccine, for comparison, is only about 50 percent effective. Public-health experts have warned for months that a coronavirus vaccine might be similarly mediocre, and was therefore unlikely to provide the silver bullet so many hoped for.
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“The best we’ve ever done is measles, which is 97 to 98 percent effective,” Dr. Anthony S. Fauci, the nation’s top infectious disease expert, told CNN in June. “That would be wonderful if we get there. I don’t think we will.”
Five months later, Fauci’s tone has changed. “I’d said I would be satisfied with a 70, 75 percent efficacy, that something like 95 percent was really aspirational,” he said Monday. “Well, our aspirations have been met, and that is really very good news,” he added, calling Moderna’s results “truly striking.”
A potential leap forward for science
If these vaccines do manage to bring the pandemic to a close, they will also open up a new era in infectious disease prevention.
For as long as vaccines have existed, most have worked by presenting the body with a weakened virus, or part of one, which trains the immune system to combat its natural incarnation.
Pfizer’s and Moderna’s belong to a new generation of vaccines. Both contain a synthetic snippet of the coronavirus’s genetic material, called messenger RNA or mRNA, that the body uses to manufacture the so-called spike protein on the virus’s surface. That protein, in turn, sets off a response that arms the immune system’s defenses.
Although many genetic vaccines are being developed for other diseases, these would be the first ever approved for human use.
[Related: “How a once-dismissed idea became a leading technology in the Covid vaccine race”]
One of the promises of genetic vaccine technology, which has been in development for 30 years, is that viral genomes can now be sequenced and synthesized in a matter of hours and weeks. “Even after we defeat Covid-19, new viruses will come along,” Walter Isaacson writes in The Washington Post. “When that happens, it will take only days to code a new RNA sequence to make a vaccine to target the new threat.”
But several steps remain before that possibility becomes reality:
The Pfizer and Moderna data still have to be reviewed by the Food and Drug Administration, and it will also be important to determine whether the vaccines work equally well in older and younger people, experts told The Times. (Moderna’s vaccine, at least, appeared protective across age groups as well as racial and ethnic ones.)
Researchers also want to know if the vaccines prevent people from spreading the virus, which could bring a swifter end to the pandemic. But as Florian Krammer, a virologist at Icahn School of Medicine at Mount Sinai in New York, told Nature, that information may be practically impossible to ascertain in a clinical setting.
Another crucial unknown is how long the vaccine-induced immunity will last. As my colleague Carl Zimmer writes, it’s possible that it will last years or diminish in months, requiring a booster.
On Twitter, Michael Mina, an assistant professor of epidemiology at Harvard, said he was slightly hesitant to assume that the vaccines would remain so effective at preventing disease over the long term, even if he was optimistic that some form of immunity would persist.
The New York Times