Pfizer-BioNTech COVID-19 vaccine (2020) E / U.S. Secretary of Defense / Wikimedia Commons / CC BY 2.0
A year into the unprecedented coronavirus pandemic, the Food and Drug Administration (FDA) has issued an Emergency Use Authorization (EUA) for COVID-19 vaccines from three companies: Pfizer-BioNTech, Moderna, and Johnson and Johnson.
COVID-19 vaccine development was the fastest seen in history due to the world’s growing technological advances. The scramble for a vaccine was one of the first responses to the coronavirus because vaccines can increase immunity. Only the immune system can fight a virus off once an individual is infected.
“Vaccines are the best way of going about preventing viruses. You can vaccinate large numbers of people and then look to generate herd immunity, where there’s just so many people who are immune to the disease that outbreaks really can’t be sustained,” said Diana Brainard, an infectious disease physician.
COVID-19 spreads through air and droplets; social distancing, wearing a mask, and washing one’s hands can prevent the virus from spreading. Vaccinations take these precautions to another level.
“Vaccines are a game-changer when it comes down to being able to decrease the effect [of the virus] on people,” said Jason Lau, a pediatric resident at the University of California, Davis. “Once enough people have vaccinations, and there’s herd immunity, we can go about more towards our normal lives, which we really can’t quite do with just masking and social distancing.”
The immune system protects the human body from infection. Different types of white blood cells help fight the infection: macrophages eat up germs and dead cells but leave behind parts of the virus, or antigens, which are dangerous to the body; B-lymphocytes then come and produce antibodies that attack the antigens; lastly, the T-lymphocytes attack the infected cells.
If an individual faces the same virus again, the T-lymphocytes left from the previous encounter, called memory cells, will know what to do and act quickly. After identifying the germ, B-lymphocytes will begin producing antibodies to fight it.
The COVID-19 vaccines teach the T-lymphocytes and B-lymphocytes how to fight the virus without having an individual get the infection.
“How we get immunity is to expose parts of the protein of the virus to our bodies, whether it be a messenger RNA (mRNA) method or an adenovirus that carries the spike protein,” Lau said. “It introduces the components of the virus to our body and allows us to mount an immune system response.”
The spike protein is a major antigen for the SARS-CoV-2 virus and appears on the virus particle’s surface, making it a target as the vaccine instruction to produce the protein.
“The Pfizer, Moderna, and Johnson and Johnson vaccines express the spike in a stabilized prefusion conformation, and this is the conformation that will induce the immune response that can potently block virus infection,” said Jing Jin, a researcher and virologist.
The three vaccines all express the same antigen but differ in how they deliver it.