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Health Team

FDA group endorses Moderna's COVID-19 vaccine

Posted December 17, 2020 6:07 a.m. EST
Updated December 17, 2020 5:08 p.m. EST

— Some of America’s most vulnerable communities will soon have a second vaccine to help protect them from COVID-19.

Advisers for the U.S. Food and Drug Administration on Thursday afternoon endorsed a vaccine developed by Moderna for emergency use.

The vote capped eight hours of discussion during FDA’s Vaccines and Related Biological Products Advisory Committee. It comes a week after the advisory group gave a favorable vote to another vaccine developed by Pfizer and BioNTech.

The vaccine, which was taken by 15,000 in trials, showed a 94% efficacy rate and showed no major safety issues.

“The data clearly shows that the benefits outweigh the risks,” said Capt. Amanda Cohn, acting chief medical officer for the National Center for Immunization and Respiratory Diseases.

None of the committee members voted against the emergency use authorization. Twenty members supported it, while Michael Kurilla abstained because he had concerns the committee's endorsement language was too broad.

“Efficacy was uniformly high across the groups,” FDA official Rachel Zhang told the committee. However, she said the sample size for some subgroups -- such as racial minorities and pregnant women -- was “small.”

Sample sizes drew some questions from committee members but, they had asked more questions about potential side effects of the vaccine.

The FDA approved a vaccine by Pfizer and BioNTech last week, shortly after reports emerged that health workers in the United Kingdom experienced anaphylactic reactions. On Tuesday, health officials in Alaska said a middle-aged woman experienced a similar reaction despite having no history of allergic reactions.

The FDA is still investigating those cases, Doran Fink, a deputy director in the FDA’s division of vaccines and related products applications, told the advisory group Thursday.

Moderna executives came to Thursday's meeting anticipating questions about the risk of allergic reactions, stating early that they found no evidence their vaccine would cause an anaphylaxis.

Two people had allergic reactions during the trial period, said David Martin, Moderna’s vice president of pharmacovigilance. One occurred in someone in the placebo group, Martin said. The other occurred 63 days after someone received the second dose of the vaccine.

That person had "a history of asthma and allergy to shellfish," Martin said.

In total, 15,000 people received the Moderna vaccine. Some experienced mild side effects, such as headache and myalgia, after taking the vaccine's second dose.

Overall, "We do not see a significant safety risk," said Tal Zaks, the company's chief medical officer.

Committee members also asked about four cases in which trial participants experienced symptoms of Bell's palsy, a condition that causes temporary weakness or paralysis of facial muscles.

One of the cases occurred in someone who received a placebo. Two of the people who experienced symptoms of Bell's palsy had previously had facial injections, said Zhang, the FDA official.

To date, the FDA has "no clear basis upon which to conclude a causal relationship” between the vaccine and the Bell's palsy, she said.

Public feedback

Multiple health experts expressed optimism about Moderna's vaccine during a public hearing.

Dougles Dieterich, a physician at Mount Sinai Institute of Liver Medicine in New York, shared his personal experience with the illness after becoming infected in March.

"I think it’s important to recognize there’s a space between life and death," Dieterich said before listing his lingering complications. He mentioned hypertension and pulmonary fibrosis, adding: “My sense of smell is completely gone.”

“As good as our treatment is now, prevention is clearly much better. There's a lot of long-term effects of Covid," Dietrich said. “I think a vaccine is the answer.”

The benefits of the vaccine outweigh the potential risks, said Renumathy Dhanasekaran, an instructor in Stanford University’s Division of Gastroenterology and Hepatology.

“I have personally seen the devastation COVID-19 has caused for our patients directly and indirectly,” she said. “Clearly, the vaccine is a welcome relief for elderly patients and those with chronic medical conditions.”

Moderna executives have said they plan to continue tracking the effects of the vaccine even after it's approved.

Roberta Luskin-Hawk, chief executive at St. Joseph Hospital’s Rural Regional Medical Center in California, said she looks forward to seeing how the vaccine will improve healthcare access.

Not only will it help prevent COVID-19, she said, the vaccine will also “help leave ICU capacity available for the care of patients with other acute medical conditions.”

Moderna vs. Pfizer

Moderna's coronavirus vaccine candidate is similar to the Pfizer-BioNTech vaccine that was authorized and shipped out to the first Americans earlier this week.

But there are a few key differences. Most importantly, Moderna's vaccine can be stored in normal freezers and does not require a super-cold transportation network, making it more accessible for smaller facilities and local communities.

Here's a look at what we know about the Moderna vaccine and how it compares to Pfizer's.

What is Moderna?

While Pfizer is a pharmaceutical behemoth, Moderna -- short for modified RNA -- is a biotech company based in Cambridge, Massachusetts.

Established in 2010, Moderna has never brought a product to market, or gotten any of its nine or so vaccine candidates approved for use by the FDA. It had also never brought a product to phase three of a clinical trial previously.

The company's scientists had already been collaborating with researchers from the National Institutes of Health on a vaccine for another coronavirus, Middle Eastern Respiratory Syndrome (MERS). When Chinese researchers released the genomic sequence for the novel coronavirus in mid-January, they had a jump start.

The vaccine, called mRNA-1273, had development help from the National Institute of Allergy and Infectious Diseases. The US Biomedical Advance Research and Development Authority, known as BARDA, supported late-stage clinical trials and has helped scale up manufacturing.

The FDA green-lit clinical trials of Moderna's vaccine on March 3, the first out of the gate. Its advanced stage clinical trial started July 27 and it was the first government-funded Phase 3 clinical trial for a Covid-19 vaccine in the US. The company applied to the FDA for emergency use authorization for the vaccine on November 30.

Does the vaccine work?

The Moderna vaccine was effective in preventing Covid-19 cases in total and in limiting severe Covid-19 during the trial.

The vaccine's efficacy against Covid-19 was 94.1%, occurring at least 14 days after the second dose, according to a briefing document released by an advisory committee to the FDA.

In Moderna's trial, 15,000 study participants were given a placebo, which is a shot of saline that has no effect. Over several months, 185 of them developed Covid-19, with 30 developing severe forms of the disease. One of them died.

Another 15,000 participants were given the vaccine, and only 11 of them developed Covid-19. None of the 11 became severely ill.

The vaccine was effective across age groups, genders, racial and ethnic groups, and participants with medical comorbidities associated with high risk of severe Covid-19, according to the briefing document. About 10% of study participants were Black and 20% were of Hispanic or Latino.

How does it work?

Like Pfizer's vaccine, Moderna's delivers messenger RNA, or mRNA, which is a genetic recipe for making a piece of the spikes that sit atop the coronavirus. Once injected, the body's immune system makes antibodies to the spikes. If a vaccinated person is later exposed to the coronavirus, those antibodies should stand at the ready to attack the virus.

The Moderna vaccine in particular contains a synthetic mRNA that codes for a structure called the "pre-fusion stabilized spike glycoprotein" of the virus.

The vaccine also contains fatty materials called lipids, tromethamine, tromethamine hydrochloride, acetic acid, sodium acetate and sucrose.

How is Moderna's vaccine different from Pfizer's?

The two vaccines are very similar, but they have a few key differences that make Moderna's vaccine "more flexible," as US Health and Human Services Secretary Alex Azar said last month.

Efficacy: Both Moderna's and the Pfizer-BioNTech vaccine have shown similar efficacy levels of near 95%.

"They appear to be roughly equivalent," said Dr. Paul Offit, a member of the FDA's vaccine advisory committee, during an appearance on CNN's "New Day" on Tuesday.

Structure: Both vaccines rely on mRNA, or messenger RNA, to work, although with slightly different structures and makeup.

"Even though they're both messenger RNA vaccines, they're really different messenger RNA molecules, they have different so-called lipid delivery systems, meaning the sort of fatty droplet in which the messenger RNA is located," Offit said on Monday. "That's why they have different storage and handling characteristics."

Cold storage: Most importantly, Moderna's vaccine does not need to be kept at super-cold temperatures, like Pfizer's.

The Pfizer vaccine needs to be stored at about minus-75 degrees Celsius, about 50 degrees colder than any vaccine currently used in the US. The vaccine can be put in the refrigerator for only up to five days before it expires.

To accommodate that, the CDC created a complex set of handling and storage requirements known as the "cold chain" that included expensive ultra-cold freezers and lots of dry ice.

In contrast, Moderna's vaccine can be kept at about minus-20 degrees Celsius, or about the temperature of a home freezer, according to Moncef Slaoui, the head of the US effort to develop a vaccine for Covid-19. Moderna's vaccine can also be kept in a refrigerator for 30 days before it expires.

"So that's more manageable and much more commonly available," Slaoui said Tuesday.

These differences suggest that Pfizer's vaccine may be used more for major institutions with established infrastructure like hospitals, while Moderna's may be more useful to smaller facilities like a local chain or pharmacist.

Dosage and timing: Moderna's vaccine is administered as two 100-microgram doses given 28 days apart. Pfizer's vaccine is administered as two 30-microgram doses given 21 days apart.

Age: If authorized, the Moderna vaccine would be used in people 18 and older, while the Pfizer vaccine was authorized for people 16 and older.

Is it safe?

The vaccine has a "favorable" safety profile, the briefing document to the FDA says, "with no specific safety concerns identified" that would prevent it from getting emergency authorization.

The most common adverse reactions to the vaccine have been injection site pain, fatigue, headache, muscle pain, joint pain and chills, according to the document. Swollen lymph nodes have also been reported.

Overall, "the frequency of non-fatal serious adverse events was low and without meaningful imbalances" between the group that received the vaccine and the group that received the placebo.

One study participant, 24-year-old Yasir Batalvi, told CNN he got a low-grade fever, fatigue and chills after getting the second shot of what he believed to be the real vaccine. He was fine by the next morning.

Slaoui, the Operation Warp Speed chief scientific adviser, has said about 10-15% of immunized study subjects will develop "quite noticeable side effects."

When will I be able to get it?

The US initially purchased 100 million doses of Moderna's vaccine, and last week agreed to buy 100 million more doses. Moderna began manufacturing the first 100 million doses while clinical trials were getting underway, Health and Human Services said in a statement.

The vaccine still has to be authorized first. The FDA's advisory committee meets Thursday to discuss emergency use authorization for it, and Slaoui said he expects the committee to approve it by Friday.

If that happens, he said to expect shipments to begin 24 hours later in order for the vaccines to arrive at facilities by Monday morning.

There will be more than 6 million doses of Moderna vaccines shipped to more than 3,200 sites, far more than the 636 sites that Pfizer's vaccines were shipped to.

From there, the vaccines will be administered in an order established by state and local authorities. Vaccine advisers to the CDC recommended that health care workers and residents of long-term care facilities be first in line for any coronavirus vaccines that get emergency approval.

CNN Chief Medical correspondent Dr. Sanjay Gupta estimated that vaccines will be generally available by late spring or early summer.

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