WASHINGTON — The coronavirus vaccine made by Moderna is highly protective, according to new data released on Tuesday, setting the stage for its emergency authorization this week by federal regulators and the start of its distribution across the country.
The Food and Drug Administration intends to authorize emergency use of the vaccine on Friday, people familiar with the agency’s plans said. The decision would give millions of Americans access to a second coronavirus vaccine beginning as early as Monday. The Pfizer-BioNTech vaccine, cleared last week, was the first to be authorized.
“This is great news, as this now brings us to two products with high levels of efficacy,” said Rupali Limaye, an associate scientist at Johns Hopkins Bloomberg School of Public Health.
The review by the F.D.A. confirms Moderna’s earlier assessment that its vaccine had an efficacy rate of 94.1 percent in a trial of 30,000 people. Side effects — including fever, headache and fatigue — were common and unpleasant, but not dangerous, the agency found.
The F.D.A. said its analysis “supported a favorable safety profile, with no specific safety concerns identified that would preclude issuance of an emergency use authorization.”
The success of Moderna’s vaccine has become all the more critical to fighting the pandemic as other vaccine efforts have faltered. The hopeful news arrives at a time of record-setting numbers of coronavirus cases that are overwhelming hospitals and of an ever-increasing death toll, which reached a bleak milestone of 300,000 on Monday.
The data release is the first step of a public review process that will include a daylong meeting on Thursday by an independent advisory panel of experts. They will hear from Moderna, F.D.A. scientists and the public before voting on whether to recommend authorization. The panel is expected to vote yes, and the F.D.A. generally follows the experts’ recommendations.
Distribution of about six million doses could then begin next week, significantly adding to the millions of doses already being shipped by Pfizer and BioNTech. Health care workers received the first shots on Monday of that vaccine, which has an efficacy rate of 95 percent.
Emergency authorization is not the same as full approval. It allows an experimental vaccine to be used if there is evidence that its potential benefits outweigh its risks, while more data is collected to apply for full approval.
Barry R. Bloom, a professor of public health at Harvard, said the results from Moderna and Pfizer were “extraordinarily comparable.”
“The good news is they both did everything they were supposed to do,” he said. Based on the data, Moderna’s vaccine may be slightly less effective in people 65 and older than Pfizer-BioNTech’s. “But it’s hard to tell,” he said.
Compared with the Pfizer-BioNTech vaccine, Moderna’s was more likely to cause headaches, sore arms and related side effects, Dr. Bloom noted.
The vaccine rollout is one of the most ambitious in the nation’s history, but experts are uncertain how long it will take for all 330 million Americans to be inoculated, let alone return the country’s businesses, schools and everyday routines to a new normal.
Last summer, the U.S. government signed deals with Moderna and Pfizer to acquire 200 million doses in the first quarter of 2021. Because both vaccines require two doses, those contracts guaranteed enough doses for 100 million people. The government announced last week that it had purchased another 100 million doses from Moderna for the second quarter, increasing the number to 150 million who can be vaccinated.
Both vaccines will be provided free of charge.
Because Moderna’s vaccine requires less extreme cold storage than the Pfizer-BioNTech product, it will be easier to ship, store and handle.
“Moderna is the one that I would take out to rural areas and community health centers and private doctors’ offices,” Dr. Bloom said, adding that hospitals would be better equipped to deal with the Pfizer-BioNTech vaccine.
Moderna’s vaccine has become a symbol of the triumphs of government scientists during the pandemic. After China released the genetic sequence of the new virus in early January, scientists at Moderna and the National Institutes of Health were able to zero in on the design for a vaccine in just two days. Unlike Pfizer, Moderna has worked closely with Operation Warp Speed, the federal program aimed at accelerating vaccine development. Nearly $2.5 billion in federal funds helped Moderna buy raw materials, expand its factory and enlarge its work force by 50 percent.
Covid-19 Vaccines ›
Answers to Your Vaccine Questions
With distribution of a coronavirus vaccine beginning in the U.S., here are answers to some questions you may be wondering about:
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- If I live in the U.S., when can I get the vaccine? While the exact order of vaccine recipients may vary by state, most will likely put medical workers and residents of long-term care facilities first. If you want to understand how this decision is getting made, this article will help.
- When can I return to normal life after being vaccinated? Life will return to normal only when society as a whole gains enough protection against the coronavirus. Once countries authorize a vaccine, they’ll only be able to vaccinate a few percent of their citizens at most in the first couple months. The unvaccinated majority will still remain vulnerable to getting infected. A growing number of coronavirus vaccines are showing robust protection against becoming sick. But it’s also possible for people to spread the virus without even knowing they’re infected because they experience only mild symptoms or none at all. Scientists don’t yet know if the vaccines also block the transmission of the coronavirus. So for the time being, even vaccinated people will need to wear masks, avoid indoor crowds, and so on. Once enough people get vaccinated, it will become very difficult for the coronavirus to find vulnerable people to infect. Depending on how quickly we as a society achieve that goal, life might start approaching something like normal by the fall 2021.
- If I’ve been vaccinated, do I still need to wear a mask? Yes, but not forever. Here’s why. The coronavirus vaccines are injected deep into the muscles and stimulate the immune system to produce antibodies. This appears to be enough protection to keep the vaccinated person from getting ill. But what’s not clear is whether it’s possible for the virus to bloom in the nose — and be sneezed or breathed out to infect others — even as antibodies elsewhere in the body have mobilized to prevent the vaccinated person from getting sick. The vaccine clinical trials were designed to determine whether vaccinated people are protected from illness — not to find out whether they could still spread the coronavirus. Based on studies of flu vaccine and even patients infected with Covid-19, researchers have reason to be hopeful that vaccinated people won’t spread the virus, but more research is needed. In the meantime, everyone — even vaccinated people — will need to think of themselves as possible silent spreaders and keep wearing a mask. Read more here.
- Will it hurt? What are the side effects? The Pfizer and BioNTech vaccine is delivered as a shot in the arm, like other typical vaccines. The injection into your arm won’t feel different than any other vaccine, but the rate of short-lived side effects does appear higher than a flu shot. Tens of thousands of people have already received the vaccines, and none of them have reported any serious health problems. The side effects, which can resemble the symptoms of Covid-19, last about a day and appear more likely after the second dose. Early reports from vaccine trials suggest some people might need to take a day off from work because they feel lousy after receiving the second dose. In the Pfizer study, about half developed fatigue. Other side effects occurred in at least 25 to 33 percent of patients, sometimes more, including headaches, chills and muscle pain. While these experiences aren’t pleasant, they are a good sign that your own immune system is mounting a potent response to the vaccine that will provide long-lasting immunity.
- Will mRNA vaccines change my genes? No. The vaccines from Moderna and Pfizer use a genetic molecule to prime the immune system. That molecule, known as mRNA, is eventually destroyed by the body. The mRNA is packaged in an oily bubble that can fuse to a cell, allowing the molecule to slip in. The cell uses the mRNA to make proteins from the coronavirus, which can stimulate the immune system. At any moment, each of our cells may contain hundreds of thousands of mRNA molecules, which they produce in order to make proteins of their own. Once those proteins are made, our cells then shred the mRNA with special enzymes. The mRNA molecules our cells make can only survive a matter of minutes. The mRNA in vaccines is engineered to withstand the cell’s enzymes a bit longer, so that the cells can make extra virus proteins and prompt a stronger immune response. But the mRNA can only last for a few days at most before they are destroyed.
Moderna’s vaccine effort stands in contrast to two other high-profile projects that the United States had hoped would build up its supply: one from the pharmaceutical companies Sanofi of France and GlaxoSmithKline of Britain, and another from the British-Swedish drug maker AstraZeneca and the University of Oxford.
AstraZeneca and Oxford ended up using two different doses in clinical trials in Britain and Brazil. At one level, the efficacy was 62 percent, and at the other it was 90 percent. The muddled results have left it unclear when AstraZeneca will have enough data to secure an emergency authorization.
Separately, Sanofi and GlaxoSmithKline had disappointing results in early clinical trials. While their vaccine produced a promising immune response in volunteers under 50, it failed to do so in older ones. The companies are planning a new set of trials with a different version, making it unlikely they can produce a vaccine before the end of 2021.
Moderna’s vaccine has had much smoother sailing. The F.D.A. review showed that it worked equally well in white, Black and Hispanic volunteers, men and women, healthy participants and those at risk of severe Covid-19 with conditions like obesity and diabetes. For people 65 and older, the trial provided an estimated efficacy of 86.4 percent, lower than the overall estimate of 94.1 percent. But the apparent difference was not statistically significant. And 86.4 percent is still very high.
So far, two potential differences between the Pfizer-BioNTech and Moderna vaccines have emerged in the F.D.A.’s reviews, but the findings may reflect a shortage of data rather than genuine distinctions.
Moderna produced more evidence that its vaccine can prevent severe disease. Of 30 volunteers who developed severe cases of Covid, all had received the placebo, not the vaccine.
Dr. Limaye called that a crucial finding.
“We’re worried about severe cases that lead to hospitalization, which leads to death,” she said. “The fact that they were able to prevent any cases of severity — I mean, that’s huge.”
On this front, the Pfizer-BioNTech findings were less compelling. Ten severe cases were reported in the placebo group and one in the vaccinated group. Those numbers are too small to gauge the vaccine’s ability to prevent serious illness.
“The available data for these outcomes did not allow for firm conclusions,” the F.D.A. said.
A second difference is that the Pfizer-BioNTech vaccine started to protect against the coronavirus within about 10 days of the first dose. Moderna’s vaccine, by contrast, did not reveal such a striking effect after the first dose.
But fewer cases of Covid occurred among participants in the early days of the Moderna trial, making it harder to measure differences between the vaccinated and the placebo groups. In any case, health officials have said that for both vaccines, two doses are essential for full protection.
How long that protection will last is still an open question. In a recent study, Moderna found that three months after the second dose, volunteers were still making high levels of antibodies. But researchers don’t yet know what levels are needed to maintain immunity. Time, and more research, will tell whether booster shots will be required.
Another puzzle is whether the vaccine can prevent people from spreading the disease, which would greatly help to stop the pandemic. Those who are infected but have no symptoms are thought to be a major source of transmission.
A vaccine that prevents illness might still allow people to become infected and harbor the virus in their noses long enough to transmit it.
New data from Moderna suggest that its vaccine may reduce transmission. Researchers found that people who had one shot were less likely than those in the placebo group to have symptom-free infections in their noses — and therefore less likely to be contagious.
The documents published Tuesday made clear that side effects were particularly common after the second dose, but typically lasted only a day. Experts say people may need to take a day off work after getting the shot.
During the Moderna trial, researchers also kept an eye out for volunteers who developed new disorders. In a trial lasting several months with 30,000 people, it is normal for some to come down with conditions that have nothing to do with the vaccine, health experts say. Comparing the rates between the vaccine and placebo groups — as well as general background rates — can help pinpoint serious concerns and rule out coincidences.
During the Moderna trial, three vaccinated participants and one in the placebo group developed a form of temporary facial paralysis called Bell’s palsy, which can last weeks or longer. It can be triggered by viral infections and other causes. Some 40,000 cases occur annually in the United States. Years of intense research have failed to find a link between the disorder and any vaccine routinely recommended in the United States.
In the review released on Tuesday, the F.D.A. said: “Currently available information is insufficient to determine a causal relationship with the vaccine.”
In the Pfizer-BioNTech trial, four cases were detected in the vaccine group, including one in a person with a history of the disorder, and none in the placebo group.
Dr. Peter Marks, the F.D.A.’s top vaccine regulator, said Monday in an interview with JAMA, that the Bell’s palsy cases were most likely not caused by the vaccine, and that the seeming difference between the two groups of volunteers was just a matter of chance.
The F.D.A. said it would recommend tracking Bell’s palsy cases as the vaccines roll out.
The agency’s analysis did not find serious allergic reactions to the Moderna vaccine. The same was true in the Pfizer-BioNTech trial, but when vaccinations for the public began in Britain last week, two health care workers with a history of serious allergies had a severe and potentially life-threatening reaction called anaphylaxis.
British health officials have said that people with a history of anaphylaxis should avoid the Pfizer-BioNTech vaccine. In the United States, the Centers for Disease Control and Prevention announced last weekend that people with serious allergies can be safely vaccinated, with close monitoring for 30 minutes after receiving the shot.
While the Moderna and Pfizer-BioNTech vaccines are similar in their ingredients, but not identical, it is not clear whether an allergic reaction to one would occur with the other. Both consist of genetic material called mRNA encased in a bubble made from a mixture of fats. The two companies use different fats.
Moderna has requested authorization to vaccinate people 18 and older, like those in its study. The Pfizer-BioNTech vaccine was authorized for people as young as 16, because the trial had some younger volunteers. Both companies are running trials on children as young as 12 and have plans to start studying even younger children.
Sharon LaFraniere and Katie Thomas contributed reporting.
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