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A COVID-19 vaccine may soon get emergency use approval from the FDA. Boston Globe/Getty Images
  • Moderna’s experimental COVID-19 vaccine had 94.1 percent efficacy based on final results from its late-stage clinical trial.
  • The company has submitted its final results to the FDA, which will review the emergency use approval (EUA) application on December 10.
  • Over 267,000 people have died from COVID-19 in the United States

Biotech company Moderna said on Monday that its experimental COVID-19 vaccine had 94.1 percent efficacy against symptomatic infection, based on final results from its late-stage clinical trial. The vaccine also had 100 percent efficacy against severe disease.

This offers another glimmer of hope in the midst of a surging pandemic, with more than 63 million cases worldwide and more than 1.4 million deaths.

In the United States, cases are rising sharply. The country recorded 2,300 deaths last Wednesday — the highest toll since May. Thanksgiving gatherings and holiday shopping may propel case numbers even higher in the coming weeks.

Moderna said it filed an application with the Food and Drug Administration (FDA) for emergency use authorization (EUA) of its vaccine. Drugmaker Pfizer filed its own application on November 20, with data showing similar high efficacy.

AstraZeneca also released preliminary results last week from its phase 3 trial, with efficacy up to 90 percent. However, the company faces questions about its study after a manufacturing error led to some participants receiving a lower, and apparently more effective, dose.

While researchers welcomed these results, they caution that final peer-reviewed data will still be needed. During its review, the FDA will have access to the full raw data from the companies’ trials.

An approved vaccine won’t be widely available until spring, although some high-risk groups may have earlier access.

Until then, physical distancing, wearing masks, and following other public health measures will be needed to slow the rise in COVID-19 hospitalizations and deaths.

Dr. Bruce Y. Lee, executive director of the Public Health Computational and Operations Research (PHICOR) group and professor of health policy and management at CUNY Graduate School of Public Health and Health Policy, said Moderna’s announcement is positive news, but we should be careful not to overhype the results.

“These are preliminary results,” he said, “and the data hasn’t gone through scientific peer review.”

In the study, 30,000 people were randomly assigned to receive either two doses of the vaccine 28 days apart, or two injections of an inactive placebo on the same schedule.

There were 196 cases of symptomatic infection among the study participants. Only 11 of those were in people who received the vaccine. The rest were in the placebo group.

All of the 30 cases of severe COVID-19 occurred in the placebo group, with no severe illness in people who had received the vaccine. One person in the placebo group died from COVID-19 during the study.

The 196 cases included 33 older adults, and 42 people who were Hispanic, Black, Asian American, or multiracial. The efficacy was similar across all subgroups, the company reported.

The results suggest that the vaccine can protect against symptomatic coronavirus infection and severe illness.

“This positive interim analysis from our phase 3 study has given us the first clinical validation that our vaccine can prevent COVID-19 disease, including severe disease,” Stéphane Bancel, CEO of Moderna, said in a news release.

Older adults also appear to be equally protected, something that does not happen with every vaccine.

“We know that other vaccines — for instance, the flu vaccine — may not work as well in older adults or in people with impaired immune systems,” Lee said.

It’s not known whether Moderna’s vaccine protects against asymptomatic infection, or if it prevents people from spreading the virus to others.

No serious negative side effects were reported during the study. The most common side effects were minor, such as pain at the injection site, fatigue, and achy muscles and joints.

While Pfizer, Moderna, and AstraZeneca are the first companies to announce early results from phase 3 clinical trials, 10 other vaccines have reached this stage of testing.

Many more candidate vaccines are in earlier stages of testing or are being tested in the lab or animals.

Moderna’s and Pfizer’s data still needs to be reviewed by the FDA, which will occur during a public meeting scheduled for December 10.

Emergency authorization would make the vaccines available to high-risk groups such as healthcare and other essential workers. Full FDA approval will be needed before widespread distribution can occur.

If the FDA grants one or both vaccines emergency approval, it might not happen until several weeks after the FDA’s meeting, reports STAT News.

The high efficacy seen with both of these experimental vaccines is encouraging, but real-world effectiveness may be lower due to a number of factors.

“It’s very standard to see lower effectiveness once a vaccine is rolled out to the population compared to the efficacy measured in a trial,” Lee said.

“So we need to see more information before we have a better sense of what the actual effectiveness and efficacy will be,” he added.

As with Pfizer’s results, several questions about Moderna’s vaccine remain.

“We would want to follow people for a longer period of time,” Lee said, “because that gives us a better sense of what the side effects are and how long this protection may last.”

Study participants were only followed for an average of 2 months after their second dose.

The Centers for Disease Control and Prevention (CDC) routinely monitors approved vaccines for adverse events.

Dr. Michael Mina, an epidemiologist at the Harvard T.H. Chan School of Public Health, wrote on Twitter that the results from the clinical trials of these two mRNA vaccines is “exceedingly encouraging.”

“These results show that these vaccines are eliciting the correct antibody responses to stop symptomatic infection!” he added.

However, he’s concerned that the protection against the virus seen in these two trials may be a shorter-lived antibody response.

“[With] these early efficacy results, we may be measuring the effects of an impressive front line army that spins up in response to the vaccine,” he wrote, “but then we should be careful not to assume the same efficacy persists to hold that line after most of the troops disappear!”

It’s also not clear whether the vaccine blocks people from transmitting the virus to others, or whether the vaccine protects people who have already been exposed to the virus.

Moderna and Pfizer’s vaccines are both based on messenger RNA, or mRNA, technology. The vaccine delivers the genetic instructions for making the coronavirus spike protein, which the virus uses to infect cells.

After the vaccine is given, cells in the body make copies of the spike protein. This triggers the immune system to produce antibodies to fight the virus.

Because the vaccine contains instructions for only one part of the virus, it doesn’t cause infection.

Vaccines using this technology are in development for protecting against Zika virus, seasonal influenza, and rabies, but none have been approved for use in people.

Although Pfizer and Moderna are using similar vaccine technologies, Moderna says its vaccine can be stored in standard freezers for 6 months and at refrigerator temperatures for 30 days.

Pfizer’s vaccine requires storage in a specialized ultracold freezer, which has set off a race among hospitals and other facilities to obtain this equipment.

The company also expects to be able to ship 20 million vaccine doses to the United States by the end of 2020. By next year, it expects to be able to ship up to 1 billion doses worldwide.

Moderna’s vaccine trial was conducted in collaboration with the National Institute of Allergy and Infectious Diseases (NIAID).

The company received funding through the U.S. federal government’s Operation Warp Speed program to help it develop the vaccine; Pfizer did not.

Dr. Anthony Fauci, director of the NIAID, said he doesn’t expect an approved vaccine to be widely available to people in the United States until spring, reported The New York Times.

However, healthcare workers, first responders, and other high-risk groups may be vaccinated earlier.