The first doses could be given as soon as next week.
The much-anticipated emergency use authorization– the first such approval in the United States -- was greeted with optimism by infectious disease and pulmonary experts, although unanswered questions remain regarding use in people with severe allergies, safety in pregnant women, and how smooth distribution will be.
"I am delighted. This is a first, firm step on a long path to getting this COVID pandemic under control," William Schaffner, MD, professor of infectious diseases at the Vanderbilt University School of Medicine in Nashville, said in an interview.
The FDA gave the green light after the Thursday recommendation from the agency's Vaccines and Related Biological Products Advisory Committee (VRBPAC) meeting. The committee voted 17-4 to recommend the emergency authorization.
The COVID-19 vaccine is "going to have a major impact here in the US. I'm very optimistic about it," Dial Hewlett, MD, a spokesperson for the Infectious Diseases Society of American, said.
Daniel Culver, DO, chair of medicine at the Cleveland Clinic, is likewise hopeful. "My understanding is that supplies of the vaccine are already in place in hubs and will be shipped relatively quickly. The hope would be we can start vaccinating people as early as next week."
Allergic Reactions Reported in the UK
After vaccinations with the Pfizer vaccine began in the UK on Tuesday, reports surfaced of two health care workers who experienced allergic reactions. They have since recovered, but officials warned that people with a history of severe allergic reactions should not receive the Pfizer vaccine at this time.
"For the moment, they are asking people who have had notable allergic reactions to step aside while this is investigated. It shows you that the system is working," Schaffner said.
Both vaccine recipients who experienced allergic reactions carried EpiPens, as they were at high risk for allergic reactions, Hewlett said. Also, if other COVID-19 vaccines are approved for use in the future, people allergic to the Pfizer vaccine might have another option, he added.
Reassuring Role Models
Schaffner supports the CDC Advisory Committee on Immunization Practices decision to start vaccinations with health care workers and residents of long-term care facilities.
"Vaccinating health care workers, in particular, will be a model for the general public," said Schaffner, who is also a former member of the IDSA board of directors. "If they see those of us in white coats and blue scrubs lining up for the vaccine, that will provide confidence."
To further increase acceptance of the COVID-19 vaccine, public health officials need to provide information and reassure the general public, Schaffner said.
Hewlett agreed. "I know there are a lot of people in the population who are very hesitant about vaccines. As infection disease specialists and people in public health, we are trying to allay a lot of concerns people have."
Reassurance will be especially important in minority communities. "They have been disproportionately affected by the virus, and they have a traditional history of not being optimally vaccinated," Schaffner said. "We need to reach them in particular with good information and reassurance…so they can make good decisions for themselves and their families."
No vaccine is 100% effective or completely free of side effects. "There is always a chance there can be adverse reactions, but we think for the most part this is going to be a safe and effective vaccine," said Hewlett, medical director at the Division of Disease Control and deputy to commissioner of health at the Westchester County Department of Health in White Plains, NY.
Distribution: Smooth or Full of Strife?
In addition to the concern that some people will not take advantage of vaccination against COVID-19, there could be vaccine supply issues down the road, Schaffner said.
Culver agreed. "In the early phases, I expect that there will be some kinks to work out, but because the numbers are relatively small, this should be okay," he said.
"I think when we start to get into larger-scale vaccination programs — the supply chain, transport, and storage will be a Herculean undertaking," Culver added. "It will take careful coordination between health care providers, distributors, suppliers, and public health officials to pull this off."
Planning and distribution also should focus beyond US borders. Any issues in vaccine distribution or administration in the United States "will only be multiplied in several other parts of the world," Culver said. Because COVID-19 is a pandemic, "we need to think about vaccinating globally."
Investigating Adverse Events
Adverse events common to vaccinations in general — injection site pain, headaches, and fever — would not be unexpected with the COVID-19 vaccines. However, experts remain concerned that other, unrelated adverse events might be erroneously attributed to vaccination. For example, if a fall, heart attack, or death occurs within days of immunization, some might immediately blame the vaccine.
"It's important to remember that any new, highly touted medical therapy like this will receive a lot of scrutiny, so it would be unusual not to hear about something happening to somebody," Culver said. Vaccine companies and health agencies will be carefully evaluating any reported adverse events to ensure no safety signal was missed in the trials.
"Fortunately, there are systems in place to investigate these events immediately," Schaffner said.
Pregnancy Recommendations Pending
One question still looms on whether COVID-19 vaccination is safe for pregnant women. This isn't just a question for the general public, either, Schaffner said. He estimated that about 70%of health care workers are women, and data suggests about 300,000 of these health care workers are pregnant.
"The CDC's Advisory Committee on Immunization Practices will speak to that just as soon as the EUA is issued," he added.
Patients are asking Culver about the priority order for vaccination. He said it's difficult to provide firm guidance at this point.
People also have "lingering skepticism" about whether vaccine development was done in a prudent way, Culver said. Some people question whether the Pfizer vaccine and others were rushed to market. "So we try to spend time with the patients, reassuring them that all the usual safety evaluations were carefully done," he said.
Another concern is whether mRNA vaccines, which includes both the Pfizer vaccine and one from Moderna,can interact with human DNA. "The quick, short, and definitive answer is no," Schaffner said. The m stands for messenger — the vaccines transmit information. "Once it gets into a cell, the mRNA does not go anywhere near the DNA, and once it transmits its information to the cell appropriately, it gets metabolized, and we excrete all the remnants."
Hewlett pointed out that investigations and surveillance will continue. Because this is an EUA and not full approval, "that essentially means they will still be obligated to collect a lot more data than they would ordinarily," he said.
How long protection will last also remains an unknown. "The big question left on the table now is the durability," Culver said. "Of course, we won't know the answer to that for quite some time."