December 11, 2020 – Today marks a historic moment in the fight against the COVID-19 pandemic as the US Food and Drug Administration (FDA) approved Pfizer and BioNTech’s coronavirus vaccine, BNT162b2, on an emergency basis for adults aged 16 years and older. The news of emergency approval brings hope to the people of the country who just witnessed 3000 plus deaths today – the highest number recorded since the inception of the pandemic. The Pfizer vaccine has already been given to people in the UK, where it was authorized for emergency use on December 2nd. Health Canada approved the vaccine on December 8th. Besides, Bahrain and Saudi Arabia have also given the go-ahead.
The emergency authorization came after the advisory panel meeting on Thursday that began with a discussion on the FDA’s study of Pfizer’s data. The meeting was composed of independent scientific experts, infectious disease doctors, and statisticians, as well as industry and consumer representatives. CDC’s plans for safety monitoring and distribution of the vaccine to the people were also discussed in the meeting.
Emergency authorization isn’t the same as full approval, which can take a few months. For now, only a selected population will be administered the vaccine. It is most likely to be started with healthcare workers and nursing home residents.
How efficacious and safe is Pfizer’s vaccine?
The details about the vaccine trials and vaccine’s efficacy and safety were published on December 10th in the New England Journal of Medicine. BioNTech’s vaccine is an mRNA-based vaccine that encodes for SARS-CoV-2 full-length spike protein. The two-dose regimen of the vaccine was found to be safe and 95% effective against COVID-19. The vaccine provided 52% protection against the virus after the very first dose, but it reached full efficacy of 95% seven days after the booster dose. The vaccine also protects against the severe COVID-19 infection with 88.9.0% efficacy after the first dose. However, it still remains to determine whether the vaccine protects children and pregnant women.
As for safety, it was generally favorable. The most commonly reported systemic events were fatigue and headache. However, there were cases of vaccine-related serious events that are worth noting. Sixty-four vaccine recipients and six placebo recipients reported lymphadenopathy. Four vaccine-related serious adverse events, including shoulder injury, right axillary lymphadenopathy, paroxysmal ventricular arrhythmia, and right leg paresthesia, were reported among vaccine recipients.
How does the vaccine fare in older individuals and ones with comorbidities?
Approximately 20% of older (>65 years) individuals were represented in the trial, and 45% of the total participants had comorbidities. The vaccine worked with approximately 95% efficacy in both the older group as well as the ones with comorbidities with the same efficacy as the younger healthy group.
Will the trials be stopped after emergency authorization?
While emergency authorization would allow immediate vaccination of the selected population, the trials will not be stopped right away. Trials will continue for 2 years to determine the vaccine’s safety, and the FDA will review six-month safety data for final approval.
How will the FDA determine if the vaccine’s efficacy in the trial is also true in the real world?
After EUA, the CDC will collect data from several large databases that track adverse events, including Vaccine Adverse Events Reporting System, run by the CDC and the FDA, CDC’s V-safe and VSD databases and databases from the Department of Veterans Affairs, Department of Defense, and Genesis Healthcare.
As for the efficacy testing, it will be done in the same way as the efficacy of the flu vaccine is tested. Individuals who will contract the infection after EUA will be first checked whether they are vaccinated. If they are, then the timing of vaccination will be checked. Currently, this will be studied among healthcare workers and later on in severely affected or hospitalized patients, the elderly, and those in long term care and with underlying conditions.
When will the vaccines be distributed in the US?
The federal government is expected to ship 2.9 million doses of the vaccine within 24 hours of the emergency authorization across the country. Another lot with the same amount of doses will be distributed 21 days after the primary dose. With these many vaccines, only a fraction of the American population will be protected. However, Dr. Moncef Slaoui has assured that by the end of February, 100 million Americans will receive the vaccine, and by the end of June, entire U.S. population will be vaccinated. “We could see people getting vaccinated Monday, Tuesday of next week,” the secretary of health and human services said on ABC’s “Good Morning America” today.
Every state, along with six major cities, has submitted a list of hospitals to the federal government that would first receive the vaccine. In Florida, five hospitals are bound to receive the vaccine in Jacksonville, Miami, Orlando, Tampa, and Hollywood.
How will the issue of allergic reaction be addressed?
We are aware of the reports of anaphylactic reaction in the recipients in the UK and are monitoring the situation closely said Marion Gruber, director of the office of vaccines research and review at the FDA, in the Thursday meeting. She added that the FDA has included warning information related to allergic reactions. Any patient who has a history of an allergic reaction to any of the vaccine components should avoid taking it.
Can a pregnant and lactating mother take the vaccine?
So far there is no data on how vaccine fares in pregnant women. However, the FDA told vaccine manufacturers to perform DART studies. These studies are done in pregnant animals meant for understanding developmental and reproductive toxicities in developing fetuses following vaccination. None of the vaccine manufacturers who are nearing Phase 3 completion have performed this study. However, Pfizer told in the meeting that preliminary results from its DART studies in Wistar rats would be out by mid-December.
However, this data will not be sufficient to demonstrate the safety of the vaccine in pregnant women. And trials including pregnant and lactating women are necessary before the vaccine can be administered to them. But experts want FDA to not completely shut the possibility of vaccinating these women as a big chunk of health care workers are women, and a large portion of them are of child-bearing age.
By Ruchi Jhonsa, Ph.D.
Video: Rajaneesh K. Gopinath, Ph.D.
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