As of October 2023, several SARS-CoV-2 vaccines are available, produced by various companies. The primary vaccines include:
1. Pfizer-BioNTech (Comirnaty) – mRNA vaccine that uses lipid nanoparticles to deliver genetic instructions for cells to produce the spike protein of the virus, prompting an immune response.
2. Moderna (Spikevax) – Similar to Pfizer-BioNTech, this is also an mRNA vaccine that generates immunity by instructing cells to create the spike protein.
3. Johnson & Johnson (Janssen) – A viral vector vaccine that uses a modified version of a common cold virus (adenovirus) to deliver instructions for making the spike protein.
4. AstraZeneca (Vaxzevria) – Another viral vector vaccine that utilizes a chimpanzee adenovirus to deliver the spike protein’s genetic material, stimulating an immune response.
5. Novavax (Nuvaxovid) – A protein subunit vaccine that contains harmless pieces of the virus (spike proteins) to provoke an immune response without using live virus.
A notable study for the Pfizer-BioNTech vaccine involved approximately 44,000 volunteers, with about half receiving the vaccine and the other half getting a placebo. The trial results showed an efficacy rate of 95% in preventing symptomatic COVID-19 after two doses. The trial also reported that severe cases were significantly reduced among those vaccinated. These promising outcomes contributed to the FDA granting Emergency Use Authorization (EUA) in December 2020 and later full approval in August 2021 (FDA, 2021).
To combat SARS-CoV-2, the body employs both innate and adaptive immune responses. Initially, the innate immune system acts as a barrier against infection through physical defenses like skin and mucous membranes, as well as immune cells like macrophages and neutrophils that respond rapidly to pathogens. If the virus breaches these defenses, the adaptive immune system is activated, involving T and B lymphocytes. T cells target infected cells, while B cells produce antibodies specific to the virus.
If vaccinated against COVID-19, the immune response would be more efficient. The vaccine primes the immune system to recognize the spike protein, leading to quicker activation of memory B and T cells upon exposure to SARS-CoV-2, thereby reducing the severity of infection or preventing it altogether.
References
U.S. Food and Drug Administration (FDA). (2021). Pfizer-BioNTech COVID-19 Vaccine. https://www.fda.gov/media/151733/download
World Health Organization (WHO). (2023). COVID-19 Vaccines. https://www.who.int/news-room/questions-and-answers/item/coronavirus-vaccines
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