On Monday, Moderna became the second company in as many weeks to announce that its experimental vaccine against covid-19 appears to be highly effective. In early data, the company claimed that the vaccine was found to be more than 90 percent effective, while being relatively well tolerated by volunteers. As with Pfizer’s similar announcement last week, though, Moderna’s claims are based on unreleased data that have yet to be verified by outside experts.
The findings were described by Moderna in a press release issued Monday morning, based on data from the Phase III study of its experimental candidate, called mRNA-1273. Like Pfizer’s candidate, Moderna’s vaccine is supposed to work by programming the body’s own cells to produce noninfectious bits of protein from the coronavirus that train the immune system to recognize and prevent illness from the actual germ. Unlike Pfizer’s version, Moderna’s vaccine was directly developed and tested out in studies with help from the U.S. federal government through the Warp Speed program (Pfizer, like other companies, did enter into a contract with the U.S. to be reimbursed for mass production of a vaccine should it be approved for use).
The early analysis of the randomized, controlled and double-blinded Phase III trial, known as COVE, comes from 95 volunteers spread across the control and experimental groups who were diagnosed with covid-19 during the study. Of those, 90 cases were in the control (placebo) group, while only five were in the group that received the vaccine. That suggests the vaccine is somewhere around 95 percent effective at preventing illness from the virus, though the company notes that this number may change by the time the study’s final results are available. The trial in full involves 30,000 volunteers, who have received two doses of the vaccine or a placebo shot.
“I think the vaccine information offers hope during what will be a challenging few months to come for our country,” Krutika Kuppalli, an assistant professor in the Division of Infectious Diseases at the Medical University of South Carolina, said in an email. “It is important to note that this is data released by press release, and so we still need information in how individuals who were elderly and those who have co-morbidities that place them at greatest risk for COVID-19 did when they received the vaccine. We also still need information on how long it will be protective for.”
To Moderna’s credit, it provided significantly more context to these early results than Pfizer did last week. The company included data on how many people came down with severe illness, another important consideration for evaluating a vaccine, as well as data on adverse effects experienced by the volunteers. Sometimes, a vaccine may not fully prevent infection but lessens the severity of the resulting illness—an effect seen with the annual flu shot, for example.
According to Moderna, none of the five patients in the vaccine group who developed covid-19 experienced severe symptoms, while 11 people in the control group did. The vaccine was also generally well tolerated, with most adverse effects being mild to moderate. Some more serious adverse effects reported after the first or second dose of the vaccine included fatigue, muscle aches, headache and redness at the injection site. These serious adverse effects, the company said, were usually short-lasting, with fewer than 10 percent of cases experiencing any individual side effect.
The early analysis was said to be conducted by a panel of independent scientists monitoring the trial, a common practice in clinical research. The findings likely underwent added scrutiny from the National Institutes of Health, Moderna’s government partner. That said, the data underlying the results has not been vetted by other outside experts, nor is it publicly available. That doesn’t mean the results are invalid or likely to be inaccurate; it just means taking them with an extra dose of skepticism.
It’s also important to note that no vaccines, even if successful, are expected to be widely available to the public until sometime next year. Currently, the world and especially the U.S. are in the grips of a resurgent pandemic, one that will have to be managed without the aid of a vaccine for the foreseeable future. There are also still questions about whether hospitals across the country will be able to easily store these vaccines once available, in part due to the very cold conditions needed to keep them viable. Moderna’s vaccine is claimed to require less extreme cold temperatures for storage than Pfizer’s version, needing only standard refrigeration for a shelf life of up to 30 days.
“I am encouraged that the Moderna vaccine does not have the same cold chain storage challenges that some of the other vaccines require, which will make it easier to roll out,” Kuppalli said.
This is now the second batch of preliminary data released in the past two weeks suggesting that a vaccine for covid-19 can be highly effective. (Russia’s candidate, Sputnik 5, is also said to be over 90% effective, but this claim is only based on “observations,” per the Russian health agency.) That does raise hopes that these vaccines are the real deal and that we can substantially cut short a pandemic that has killed over 1.3 million people worldwide and nearly 250,000 Americans already.
“Overall, this is another promising step in the road to containing the covid-19 pandemic,” Kuppalli said.
Moderna plans to submit its data to the Food and Drug Administration in the coming weeks for a potential emergency use approval, as well as to other regulatory agencies elsewhere. Any such approval would likely arrive sometime in late December, and the first limited doses are likely to go to high-risk groups such as health care workers. Moderna has said that it expects to have about 20 million doses of the two-dose vaccine ready to ship in the U.S. by end of the year.
For now, though, we all have to stay vigilant in lowering our risk of catching and spreading this viral illness, at least for a while longer. The light at the end of the tunnel may be here sooner than expected.