Pfizer–BioNTech COVID-19 vaccine
The Pfizer–BioNTech COVID-19 vaccine, sold under the brand name Comirnaty, is an mRNA-based COVID-19 vaccine developed by the German biotechnology company BioNTech. For its development, BioNTech collaborated with the American company Pfizer to carry out clinical trials, logistics, and manufacturing. It is authorized for use in humans to provide protection against COVID-19, caused by infection with the SARS-CoV-2 virus. The vaccine is given by intramuscular injection. It is composed of nucleoside-modified mRNA that encodes a mutated form of the full-length spike protein of SARS-CoV-2, which is encapsulated in lipid nanoparticles. Initial guidance recommended a two-dose regimen, given 21 days apart; this interval was subsequently extended to up to 42 days in the United States, and up to four months in Canada.
Clinical trials began in April 2020; by November 2020, the vaccine had met the primary efficacy goals of the phaseIII clinical trial, with over 40,000 people participating. Interim analysis of study data showed a potential efficacy of 91.3% in preventing symptomatic infection within seven days of a second dose and no serious safety concerns. Most side effects are mild to moderate in severity and resolve within a few days. Common side effects include mild to moderate pain at the injection site, fatigue, and headaches. Reports of serious side effects, such as allergic reactions, remain very rare with no long-term complications documented.
The vaccine is the first COVID19 vaccine to be authorized by a stringent regulatory authority for emergency use and the first to be approved for regular use. In December 2020, the United Kingdom was the first country to authorize its use on an emergency basis. It is authorized for use at some level in the majority of countries. On 23 August 2021, the Pfizer–BioNTech vaccine became the first COVID-19 vaccine to be approved in the US by the Food and Drug Administration. The logistics of distributing and storing the vaccine present significant challenges due to the requirement for its storage at extremely low temperatures.
In August 2022, a bivalent version of the vaccine was authorized for use as a booster dose in individuals aged twelve and older in the US. The following month, the BA.1 version of the bivalent vaccine was authorized as a booster for use in the UK. The same month, the European Union authorized both the BA.1 and the BA.4/BA.5 booster versions of the bivalent vaccine. In August 2024, the FDA approved and granted emergency authorization for a monovalent Omicron KP.2 version of the Pfizer–BioNTech COVID-19 vaccine. The approval of Comirnaty was granted to BioNTech Manufacturing GmbH. The EUA amendment for the Pfizer-BioNTech COVID-19 Vaccine was issued to Pfizer Inc. The emergency use authorization was revoked in August 2025.
Medical uses
The Pfizer–BioNTech COVID-19 vaccine is used to provide protection against COVID-19, caused by infection with the SARS-CoV-2 virus, by eliciting an immune response to the S antigen. The vaccine is used to reduce morbidity and mortality from COVID-19.The vaccine is supplied in a multidose vial as "a white to off-white, sterile, preservative-free, frozen suspension for intramuscular injection". It must be thawed to room temperature and diluted with normal saline before administration.
The initial course consists of two doses. The World Health Organization recommends an interval of three to four weeks between doses. Delaying the second dose by up to twelve weeks increases immunogenicity, even in older adults, against all variants of concern. Authors of the Pitch study think that the optimal interval against the Delta variant is around eight weeks, with longer intervals leaving receptors vulnerable between doses.
A third, fourth, or fifth dose can be added in some countries.
Effectiveness
A test-negative case-control study published in August 2021, found that two doses of the BNT162b2 vaccine had 93.7% effectiveness against symptomatic disease caused by the alpha variant and 88.0% effectiveness against symptomatic disease caused by the delta variant. Notably, effectiveness after one dose of the Pfizer vaccine was 48.7% against alpha and 30.7% against delta, similar to effectiveness provided by one dose of the ChAdOx1 nCoV-19 vaccine.
In August 2021, the US Centers for Disease Control and Prevention published a study reporting that the effectiveness against infection decreased from to when the Delta variant became predominant in the US, which may be due to unmeasured and residual confounding related to a decline in vaccine effectiveness over time.
Unless indicated otherwise, the following effectiveness ratings are indicative of clinical effectiveness two weeks after the second dose. A vaccine is generally considered effective if the estimate is ≥50% with a >30% lower limit of the 95% confidence interval. Effectiveness is generally expected to slowly decrease over time.
In November 2021, Public Health England reported a possible but extremely small reduction in effectiveness against symptomatic disease from the Delta sublineage AY.4.2 at longer intervals after the second dose.
Preliminary data suggest that the effectiveness against the Omicron variant starts to decline in about 10 weeks, either after the initial two-dose regimen or after the booster dose. For other variants, the effectiveness of the initial doses starts to decline in about six months. A case-control study in Qatar from 1 January to 5 September 2021 found that effectiveness against infection peaked at in the first month after the second dose, followed by a slow decline that accelerated after the fourth month, reaching 20% at months 5 to 7. A similar trajectory was observed against symptomatic disease and against specific variants. Effectiveness against severe disease, hospitalization and death was more robust, peaking at in the second month and remaining almost stable through the sixth month, declining thereafter.
In October 2021, a phase III trial showed that a booster dose given approximately 11 months after the second dose restored the protective effect to the efficacy level against symptomatic disease from the Delta variant.
In December 2021, Pfizer and BioNTech reported that preliminary data indicated that a third dose of the vaccine would provide a similar level of neutralizing antibodies against the Omicron variant as seen after two doses against other variants.
In December 2021, private health insurer Discovery Health, in collaboration with the South African Medical Research Council, reported that real-world data from more than 211,000 cases of COVID-19 in South Africa, of which 78,000 were of the Omicron variant, indicate that effectiveness against the variant after two doses is about 70% against hospital admission and 33% against symptomatic disease. Protection against hospital admission is maintained for all ages and groups with comorbidities.
A study of the bivalent booster effectiveness against severe COVID-19 outcomes in Finland, September 2022–January 2023, has shown that it reduced the risk of severe COVID-19 outcomes among the elderly. By contrast, among the chronically ill 18–64-year-olds the risk was similar among those who received bivalent vaccine and those who did not. Among the elderly a bivalent booster provided highest protection during the first two months after vaccination, but thereafter signs of waning were observed. The effectiveness among individuals aged 65–79 years and those aged 80 years or more was similar.
Specific populations
Based on the results of a preliminary study, the U.S. Centers for Disease Control and Prevention recommends that pregnant women get vaccinated with the COVID19 vaccine.A statement by the British Medicines and Healthcare products Regulatory Agency and the Commission on Human Medicines reported that the two agencies had reached a conclusion that the vaccine is safe and effective in children aged between 12 and 15 years.
In May 2021, experts commissioned by the Norwegian Medicines Agency concluded that the Pfizer-BioNTech vaccine is the likely cause of ten deaths of frail elderly patients in Norwegian nursing homes. They said that people with very short life expectancies have little to gain from vaccination, having a real risk of adverse reactions in the last days of life and of dying earlier.
A 2021 report by the New South Wales Government in Australia found that the Pfizer-BioNTech vaccine is safe for those with various forms of immunodeficiency or immunosuppression, though it does note that the data on said groups is limited, due to their exclusion from many of the vaccine earlier trials held in 2020. It notes that the World Health Organization advises that the vaccine is among the three COVID-19 vaccines it deems safe to give to immunocompromised individuals, and that expert consensus generally recommends their vaccination. The report states that the vaccines were able to generate an immune response in those individuals, though it does also note that this response is weaker than in those that are not immunocompromised. It recommends that specific patient groups, such as those with cancer, inflammatory bowel disease and various liver diseases be prioritised in the vaccination schedules over other patients that do not have said conditions.
In September 2021, Pfizer announced that a clinical trial conducted in more than 2,200 children aged 5–11 has generated a "robust" response and is safe.
Adverse effects
In Phase III trials for the vaccine, there were no safety concerns and few adverse events.Most side effects of the Pfizer–BioNTech COVID19 vaccine are mild to moderate in severity, and are gone within a few days. They are similar to other adult vaccines and are normal signs that the body is building protection to the virus. During clinical trials, the common side effects affecting more than one in 10 people are : pain and swelling at the injection site, tiredness, headache, muscle aches, chills, joint pain, fever or diarrhea. Fever is more common after the second dose.
The European Medicines Agency regularly reviews the data on the vaccine's safety. The safety report published on 8 September 2021 by the EMA was based on over 392million doses administered in the European Union. According to the EMA "the benefits of Comirnaty in preventing COVID19 continue to outweigh any risks, and there are no recommended changes regarding the use of this vaccine." Rare side effects include temporary one sided facial drooping and allergic reactions, such as hives or swelling of the face.