In virology, a spike protein or peplomer protein is a protein that forms a large structure known as a spike or peplomer projecting from the surface of an enveloped virus. The proteins are usually glycoproteins that form dimers or trimers.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus behind the worldwide outbreak of COVID-19 disease. One of the key biological characteristics of SARS-CoV-2, as well as several other viruses, is the presence of spike proteins that allow these viruses to penetrate host cells and cause infection.

An overview of the coronavirus structure

Coronaviruses (CoVs) like the Middle East respiratory syndrome (MERS)-CoV, which had infected almost 2,500 individuals by the end of 2019, as well as the novel severe acute respiratory syndrome (SARS)-CoV-2, are enveloped and spherical viruses that typically measure between 80 and 120 nanometers (nm) in size.

The RNA genome of coronaviruses, which, at a median length of 29 kb is the longest among all RNA viruses, is comprised of six to ten open reading frames (ORFs) that are responsible for encoding both the replicase and structural proteins for the virus.

Each of the components of the viral genome is packaged into a helical nucleocapsid that is surrounded by a lipid bilayer.

The viral envelope of coronaviruses is typically made up of three proteins that include the membrane protein (M), the envelope protein (E), and the spike protein (S).

All the myths and facts about COVID-19 vaccines

Pfizer

The most commonly reported side effects, which typically lasted several days, were pain at the injection site, tiredness, headache, muscle pain, chills, joint pain, and fever. Of note, more people experienced these side effects after the second dose than after the first dose, so it is important for vaccination providers and recipients to expect that there may be some side effects after either dose, but even more so after the second dose.

On December 11, 2020, the U.S. Food and Drug Administration issued the first emergency use authorization (EUA) for a vaccine for the prevention of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in individuals 16 years of age and older. On May 10, 2021, the FDA expanded the emergency use authorization for the Pfizer-BioNTech COVID-19 Vaccine to include adolescents 12 through 15 years of age. On June 25, 2021, the FDA revised the patient and provider fact sheets regarding the suggested increased risks of myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the tissue surrounding the heart) following vaccination. On August 12, 2021, the FDA amended the Pfizer-BioNTech COVID-19 Vaccine EUA to allow for an additional dose to be given to certain immunocompromised individuals. The emergency use authorization allows the Pfizer-BioNTech COVID-19 Vaccine to be distributed in the U.S.

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Emergency Use Authorization Status: Authorized Name: Pfizer-Bio NTech COVID-19 Vaccine Manufacturer: Pfizer Inc.