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The FDA has authorized Pfizer’s COVID-19 vaccine. Now what?

Millions of Americans will soon be in line for COVID-19 shots.

On December 11, the Food and Drug Administration granted an emergency use authorization for the Pfizer-BioNTech vaccine to those over 16 years of age. The decision comes as the number of COVID-19 cases, hospitalizations and deaths have increased at an alarming rate. The United States recorded a record 3,411 deaths from COVID-19 on December 9th.

The United States is the last country to authorize the vaccine, after the United Kingdom, Canada, Bahrain and Saudi Arabia (SN: 02/12/20).

This is what happens next in the United States.

The vaccine is starting to be shipped, but will not have a widespread impact for several months.

The Pfizer-BioNTech vaccine will likely be a huge help in keeping some people out of hospitals immediately and preventing deaths.

But while the vaccine and any other that is authorized can protect individuals, when it comes to widespread changes in public health, "it will probably be several months before we have all the positive impact of a vaccine," said the infectious disease expert. Anthony Fauci on Dec. 11 in an online interview with JAMA.

Initial doses of vaccines will be limited. The federal government had already said 6.4 million doses of Pfizer would be shipped to states within 24 hours of FDA authorization. On Dec. 9, a senior Trump Administration Warp Speed ​​official said only about half of those doses, about 2.9 million, will be shipped within 24 hours of the emergency use authorization. Another 2.9 million will be kept for distribution until the first vaccinated people have to make their second shot 21 days later. Another half a million doses were reserved in a reserve, U.S. Army General Gustave Perna, who is Warp Speed's chief of operations, said at a news conference. Vaccines could begin early next week.

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A similar vaccine made by the Modern Biotechnology Company will be reviewed by an FDA advisory committee on Dec. 17. 12.5 million initial doses of that vaccine are expected to be delivered if authorized.

Overall, "we believe there will be enough vaccine available for the first 20 million vaccines in December," Alex Azar, the secretary of health and human services, said at the Dec. 9 press conference.

An advisory panel from the Centers for Disease Control and Prevention recommended that health workers and people living in nursing homes be the first to receive vaccines, if both are authorized (SN: 12/1/20). But it will be up to the states to work out the details of who gets it exactly and when.

Scientists will look for hidden side effects and other health issues.

When those doses are injected into the arms, scientists will be looking for answers to key questions. One big one: are there any hidden side effects?

In the UK, two people have had severe allergic reactions after getting the Pfizer vaccine since its launch on December 8, leading health officials there to recommend that people with "significant allergies" that trigger anaphylaxis not take it. the vaccine.

These allergic reactions raise questions about whether the vaccine can cause very rare side effects that have not been seen in clinical trials. The trials, which included more than 40,000 people, found the vaccine is safe, with side effects that include fever, chills, headache, pain at the injection site and fatigue. These side effects tended to last only a day or two and were usually mild to moderate.

While these side effects may be unpleasant for some people, they are common reactions to vaccines approved for other diseases, experts say. But some side effects may come to light only once millions have been vaccinated instead of thousands.

And while millions of people get vaccinated, many other health problems can arise, including deaths, which may not be vaccine-related but may be difficult to separate, says Marm Kilpatrick, an infectious disease researcher at the University of California, Santa Cruz. .

Six people died during clinical trials, although only two were in the vaccine group. Their deaths, from a heart attack and a pre-existing narrowing of blood vessels, were almost certainly not related to the vaccine, Kilpatrick says, but as many people are vaccinated, more deaths will occur by chance, especially among people with health. “Distinguishing the cause of all their deaths by any vaccination-related effect will not be trivial,” he says.

People who already had COVID-19 may also need to be vaccinated.

A small number of people in the Pfizer study had antibodies in their blood that indicated they had been infected before joining the study. Some of these people developed COVID-19 during the study. This may suggest that having the disease does not completely protect people from reinfection and that people who previously had COVID-19 should also be vaccinated.

But Kilpatrick, of the University of California, Santa Cruz, is not convinced. “I wouldn’t say this data is evidence that previous infection offers no protection,” he says. It’s important to know when those people had COVID-19, he says. Some people may continue to produce viral RNA for long periods of time, so some of the RNAs detected may not come from a true reinfection, but left over from the first attack of disease.

To determine if there is reinfection, doctors would have to determine the genetic composition of the virus causing the first round of disease and compare it with the virus causing later rounds, which was done for some confirmed cases of reinfections (SN: 8 / 24/20) .

Mark Slifka, a microbiologist and immunologist at Oregon Health & Science University in Portland, is also unaware of whether previously infected people could come out with a single vaccine to boost their natural immunity or whether two vaccines will be needed like everyone else.

Scientists will fight if people from the placebo group are vaccinated.

Another giant question is how long the vaccine-induced protection against coronavirus lasts. Researchers could learn this over time by tracking cases that arose in the placebo group and in the vaccine group. But that also raises a big question: Should people in the placebo group have access to the vaccine? Pfizer has proposed vaccinating the placebo group, but some scientists argue that doing so would make it impossible to know the duration of protection and long-term side effects.

People in the trial might ask if they received the vaccine or not and ask about the vaccine if they were part of the placebo group, but Slifka expects trial participants to continue to maintain their ignorance of which group they are in. Knowing it could change tells the participant’s behavior and tarnishes the data coming out of the trial.

The altruism of many participants will likely lead them to continue the trial as it is. “The people who are in these studies are heroes,” Slifka says. "They stepped up and pulled out their arms to get an experimental vaccine, not just for them, but for the country and the world."

But it becomes a more complicated question about what to do with future vaccine trials. When vaccines are approved, it is unethical to do placebo-controlled trials. Instead, companies must show that their vaccines cause immune reactions that are at least as strong as an existing vaccine.

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This is usually done by measuring the levels of antibodies produced after vaccination. If a new vaccine meets a certain standard level known as a protector (called an immune correlate), it can also be approved, as long as it is safe. But no one knows what level of antibodies or other defenses are needed to protect against COVID-19.

In addition, the Pfizer vaccine is not yet fully approved and is in limited quantities, so other companies may still need to compare vaccines to placebos to determine if they work. Once vaccines are authorized, it may be difficult to recruit people to participate in these trials.

Research will continue on whether the vaccine works for children and other groups.

Although trials have found that the Pfizer-BioNTech vaccine is 95 percent effective overall, there are not enough data to show that it is true for all populations.

Take children: Pfizer has been testing its vaccine in teens 12 years of age and older and Moderna began testing its vaccine in teens on December 10th. There is still not enough data to say how well the vaccine works for them.

No company has tested COVID-19 vaccines in children under 12 years of age. Children tend to develop milder symptoms of COVID-19 than adults. As a result, trials to test efficacy would have to be huge if they were done in the same way for children as in adults. In contrast, vaccine manufacturers can measure antibodies in younger vaccinated children to see if children have the same type of immune reactions to the vaccine as adults and adolescents.

There are also limited data on the proper functioning of the Pfizer-BioNTech vaccine in people with HIV or hepatitis B or hepatitis C or in other people with immunosuppression.

“If you have a person on chemotherapy for cancer or an autoimmune disease, the likelihood … is that their level of response to any vaccine is not as robust as someone who doesn’t have an underlying disease,” Fauci said. December 11th. "It simply came to our notice then. That means you have to vaccinate them. But you have to be prepared to not necessarily have 95 percent protection. "

COVID-19 vaccines were feared not to work well for the elderly or obese, because age and obesity can decrease immune responses and people in both groups have a higher risk of developing severe COVID-19 or dying (SN). : 22/04/20). But data from Pfizer trials suggest that the vaccine works just as well in people 65 and older than in younger adults. Obese people were also protected at levels similar to non-obese people. Scientists will want to confirm that these groups are actually protected by the vaccine.

Pfizer-BioNTech will continue to seek full FDA approval of its vaccine.

The company will likely need to collect additional safety and efficacy data to obtain full approval from the FDA and other regulatory agencies around the world. Emergency use authorization is provisional and only lasts as long as the emergency continues, said Peggy Hamburg, a former FDA commissioner during a Dec. 3 news conference hosted by SciLine, a free, independent service for journalists based in the American Association. for the Advancement of Science. .

Total approval would mean that the vaccine meets all safety and efficacy standards and is no longer experimental. The vaccine would become the standard by which any new COVID-19 vaccine is judged.

Vaccine developers are also not allowed to market their product under emergency use provisions as they can when the product obtains full FDA approval.

Does life, slowly, return to any appearance of normalcy?

Even with multiple vaccines, life may not return to pre-pandemic normalcy soon. “My optimistic hope is that we will return to more normal life by the fall,” says Ross McKinney Jr., a pediatric infectious disease specialist and scientific director of the Association of American Medical Colleges, based in Washington, D.C.

Controlling the pandemic with the use of masks, social distancing, avoiding meetings especially indoors, and taking other security measures will be key to “getting out on the other side,” says Jason Schwartz, a vaccination policy researcher at the Yale School of Public Health. "Vaccines are amazing," he says, but "they can't work miracles."

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