Pfizer’s COVID-19 vaccine gets full FDA approval as Delta variant spreads, boosters shots soon available for the vaccinated

August 30 - September 5, 2021

By Wesley Brown


Some 18 months after competition to find a cure for the COVID-19 began in earnest early 2020, the Food and Drug Administration has fully approved the first COVID-19 vaccine to marketed and sold to the public.


On Aug. 23, FDA officials said that Pfizer-BioNTech COVID-19 vaccine formerly known as BNT162b2 will now be marketed as Comirnaty for the prevention of COVID-19 disease in individuals 16 years of age and older. The vaccine also continues to be available under emergency use authorization (EUA), including for individuals 12 through 15 years of age and for the administration of a third dose in certain immunocompromised individuals.


“The FDA’s approval of this vaccine is a milestone as we continue to battle the COVID-19 pandemic. While this and other vaccines have met the FDA’s rigorous, scientific standards for emergency use authorization, as the first FDA-approved COVID-19 vaccine, the public can be very confident that this vaccine meets the high standards for safety, effectiveness, and manufacturing quality the FDA requires of an approved product,” said Acting FDA Commissioner Dr. Janet Woodcock.


“While millions of people have already safely received COVID-19 vaccines, we recognize that for some, the FDA approval of a vaccine may now instill additional confidence to get vaccinated,” continued Woodcock. “Today’s milestone puts us one step closer to altering the course of this pandemic in the U.S.” 


Since Dec. 11, 2020, the Pfizer-BioNTech vaccine has been available under so-called emergency use authorization (EUA) for anyone older than age 16. That authorization was expanded to include those 12 through 15 years of age in May. In Arkansas, the first shipments of the drug began arriving in Arkansas and other states across the U.S. on Dec. 14, only two days EUA approval.


Comirnaty, which requires two injections 21 days apart, has demonstrated 91%-95% efficacy against COVId-19 with minimal side effects, and works on messenger RNA (mRNA) technology, which instructs cells in the body to make different proteins. The result of a person receiving a mRNA vaccine is that the immune system will ultimately react defensively to COVID-19. 


FDA officials said EUAs can be used by the federal agency during public health emergencies to provide access to medical products or drugs that may be effective in treating a disease, provided it outweighs any known or potential risks of the product.


Under normal circumstances, FDA-approved vaccines undergo the agency’s standard process for reviewing the quality, safety and effectiveness of medical products. Then the FDA evaluates data and information included in the manufacturer’s submission of a biologics license application (BLA), which is a comprehensive document that is submitted to the agency providing very specific requirements. 


For Comirnaty, the FDA said the vaccine license builds on the extensive data and information previously submitted that supported the EUA, such as preclinical and clinical data and information, details of the manufacturing process, vaccine testing results, and inspections of the sites where the vaccine is made. The agency also conducts its own analyses of the information in application to make sure the vaccine is safe and effective and meets the FDA’s standards for approval. 


“Our scientific and medical experts conducted an incredibly thorough and thoughtful evaluation of this vaccine. We evaluated scientific data and information included in hundreds of thousands of pages, conducted our own analyses of Comirnaty’s safety and effectiveness, and performed a detailed assessment of the manufacturing processes, including inspections of the manufacturing facilities,” said Dr. Peter Marks, director of FDA’s Center for Biologics Evaluation and Research. “We have not lost sight that the COVID-19 public health crisis continues in the U.S. and that the public is counting on safe and effective vaccines. The public and medical community can be confident that although we approved this vaccine expeditiously, it was fully in keeping with our existing high standards for vaccines in the U.S.”


To support the Aug. 23 approval, the FDA said it reviewed updated data from the clinical trial which supported the EUA and included a longer duration of follow-up in a larger clinical trial population. Specifically, in the FDA’s review for approval, the agency analyzed effectiveness data from approximately 20,000 vaccine and 20,000 placebo recipients ages 16 and older who did not have evidence of the COVID-19 virus infection within a week of receiving the second dose. 


Also, the safety of Comirnaty was evaluated in approximately 22,000 people who received the vaccine and 22,000 people who received a placebo, the FDA said. More than half of the clinical trial participants were followed for safety outcomes for at least four months after the second dose. Overall, approximately 12,000 recipients have been followed for at least 6 months.


According to FDA and Pfizer, the most reported side effects by clinical trial participants who received Comirnaty were pain, redness and swelling at the injection site, fatigue, headache, muscle or joint pain, chills, and fever. Still, officials said, the vaccine is effective in preventing COVID-19 and potentially serious outcomes including hospitalization and death.


Additionally, the FDA said it also conducted a rigorous evaluation of the post-authorization safety surveillance data pertaining to myocarditis and pericarditis following administration of the Pfizer-BioNTech vaccine and has determined that the data demonstrate increased risks, particularly within the seven days following the second dose. 


The FDA and Centers for Disease Control and Prevention, which are both a part of the U.S. Department of Health and Human Services, also said they are monitoring any safety concerns that are identified and evaluated in a timely manner, such as risks of myocarditis and pericarditis following vaccination with Comirnaty. 


Myocarditis is inflammation of the heart muscle, and pericarditis is inflammation of the lining outside the heart. In both cases, the body’s immune system is causing inflammation in response to an infection or some other trigger. Symptoms can include chest pain, shortness of breath, or palpitations. Since April 2021, the CDC has reported increased cases of myocarditis and pericarditis in the U.S.  from both the Pfizer-BioNTech and Moderna vaccine, particularly in adolescents and young adults.


FDA and CDC officials said further studies will include an evaluation of long-term outcomes among individuals who develop myocarditis following vaccination with Comirnaty. Although not required, Pfizer has also committed to additional post-marketing safety studies to evaluate pregnancy and infant outcomes from taking the fully approved vaccine.


While the FDA granted the Pfizer application “priority review” status under former President Donald Trump’s Operation Warp Speed program to accelerate the development of a COVID-19 cure, no other vaccine has move beyond the EUA stage yet. However, Moderna is expected to also gain full FDA approval in coming days.


On Dec. 18, 2020, Moderna was the second pharmaceutical firm to receive EUA for prevention of COVID-19 only a week after Pfizer. Last week, the FDA amended the EUAs for both the Pfizer-BioNTech and Moderna vaccines to allow for booster shots for patients with weak immune systems amid concerns about the spread of the highly transmittable Delta variant.


That reversed an earlier decision by the Biden administration in July where FDA and CDC officials said a third dose of the two vaccines that use mRNA technology-based would not be needed anytime soon. CDC, FDA and HHS officials followed up that decision on Aug. 18 with another joint statement that on the Biden administration had conducted an independent evaluation and now recommends that all vaccinated Americans receive booster shots in the fall.


 “We have developed a plan to begin offering these booster shots this fall subject to FDA conducting an independent evaluation and determination of the safety and effectiveness of a third dose of the Pfizer and Moderna mRNA vaccines …,” said CDC Director Rochelle Walensky. “We are prepared to offer booster shots for all Americans beginning the week of Sept. 20 and starting 8 months after an individual’s second dose. At that time, the individuals who were fully vaccinated earliest in the vaccination rollout, including many health care providers, nursing home residents, and other seniors, will likely be eligible for a booster.


Meanwhile, the Johnson and Johnson vaccine, which received FDA emergency use authorization on Feb. 27, requires only one dose and is based on viral vector technology that alters the coronavirus so it cannot harm the body. On April 23, the FDA amended the company’s EUA to include information about a very rare and serious type of blood clot in people who receive the vaccine.


As noted, the competition to find a COVID-19 vaccine first kicked off in February 2020 after a National Institute of Health sponsored a randomized, controlled clinical trial to evaluate the investigational antiviral drug remdesivir, produced by Foster City, Calif.-based Gilead Science Inc. At the time, remdesivir was previously tested in humans with Ebola virus disease and has shown promise in animal models for treating Middle East respiratory syndrome (MERS) and severe acute respiratory syndrome (SARS), which are caused by other coronaviruses. 


The FDA has also issued an EUA for remdesivir for the treatment of hospitalized patients with severe COVID-19, including former President Donald Trump. However, the FDA emphasizes that remdesivir is still an investigational drug whose safety and efficacy for the treatment of COVID-19 as a vaccine has not been established.    


PHOTO CAPTION:  On Aug. 23, the Food and Drug Administration endorsed Comirnaty as the first fully approved vaccine for the prevention of COVID-19 in adults 16 years or older. The two-dose drug was previously known as the Pfizer-BioNTech BNT162b2 vaccine that  received FDA emergency use authorization (EUA) on Dec. 11, 2020.