Individuals must receive both doses of the COVID-19 vaccine if the vaccine is a two-dose regimen to receive the maximum protection against COVID-19.
The CDC also highlights that vaccines for COVID-19 are not ''interchangeable.'' If one had a Pfizer-BioNTech vaccination, they must get a second dose from the same vaccine company. Even if the first dosage causes adverse effects, an individual should obtain a second dose except if a vaccine provider or doctor recommends otherwise. Suppose other diseases or drugs have impaired immune systems; in that case, an individual can still have the COVID-19 vaccine if they haven't had a severe or immediate allergic reaction to any of the vaccine's ingredients.
Dr. Soumya Swaminathan, WHO's Chief Scientist, discusses in Science in 5 why it's crucial to obtain the second dosage if the vaccination is a two-dose schedule. Swaminathan explains that the first dose primes the immune system by exposing it to the new antigen. At the same time, the second dose stimulates the immune system so that the antibody and T cell-mediated responses are strong. She adds that a long-lasting memory response is created so that when the body encounters the antigen, viral protein repeatedly, it will react quickly.
Initial studies observed that the Pfizer-BioNTech and Moderna vaccines elicited a mild immune response when given a single dose. A second dosage, on the other hand, induced a more robust immune response, states Healthline. With the first dose of the COVID-19 vaccine, the course of building up protection begins. The second dosage works to bolster this protection even further.
Among the COVID-19 vaccines that require two doses, including those currently in development, are Oxford-AstraZeneca, Novavax, Sputnik V, Coronavac, Pfizer-BioNTech, and Moderna states Healthline.
Johnson & Johnson developed the COVID-19 vaccine, which only requires one dose. The FDA has authorized this vaccine Emergency Use Authorization in the U.S. after examining safety and effectiveness data from large-scale clinical trials.
The immunological response to the first dosage is insufficient in vaccinations with a two-dose schedule, and the second dose assists in the development of cell-mediated immunity. Hence, receiving a second dose of the COVID-19 vaccine is crucial.