Duration of COVID-19 Vaccine Immunity
The global race to combat the COVID-19 pandemic has led to the development of several vaccines, each with its unique technology and administration requirements. This article provides an overview of five leading vaccines: Moderna, Pfizer-BioNTech, Johnson & Johnson, Oxford-AstraZeneca, and Novavax.
The Moderna, Pfizer-BioNTech, and Johnson & Johnson vaccines are currently approved for use in the United States. The Moderna (mRNA-1273) and Pfizer-BioNTech (Comirnaty) vaccines use mRNA technology, instructing cells to produce a protein from the SARS-CoV-2 virus, triggering an immune response. The Johnson & Johnson (Janssen) vaccine, on the other hand, is an adenovirus vector vaccine that uses a lab-created inactive adenovirus as a shell for spike proteins from the SARS-CoV-2 virus.
The Oxford-AstraZeneca and Novavax vaccines, while not yet approved for use in the US, are distributed in several countries worldwide. The Oxford-AstraZeneca vaccine, like the Johnson & Johnson vaccine, uses adenovirus vector technology. It requires two doses, given 4 to 12 weeks apart, and provides immunity for about 3 months. Novavax is a protein adjuvant vaccine that uses proteins from the SARS-CoV-2 made into nanoparticles. It requires two doses, 21 days apart, and has shown to be about 89.7 percent effective in preventing COVID-19 and 100 percent effective in preventing serious illness.
All five vaccines have demonstrated effectiveness against variants such as the Beta, Gamma, and Delta variants. Early evidence suggests that the Johnson & Johnson vaccine is very likely to be effective in protecting recipients from variants. An August 2021 pre-print study found the Oxford-AstraZeneca vaccine was at least 67 percent effective against the Delta variant. Moderna, Pfizer-BioNTech, and Novavax vaccines have also shown effectiveness against these variants.
Immunity from the Moderna, Pfizer-BioNTech, and Johnson & Johnson vaccines is achieved 2 weeks after the second dose, while immunity from the Novavax vaccine is achieved 2 weeks after the second dose, given 21 days apart. Immunity from the Oxford-AstraZeneca vaccine is achieved 15 days after the second dose, and immunity from the Johnson & Johnson vaccine is achieved 2 weeks after a single dose.
Trials are still being done to determine how long immunity from the Novavax vaccine will last, but the efficacy data suggests that the Moderna vaccine provides immunity for at least 6 months, Pfizer-BioNTech for about 6 months, and Novavax for about 6 months. Protection against COVID-19 with the Johnson & Johnson vaccine is expected to last at least 8 months according to pre-print studies released in July 2021.
Booster shots have also been a topic of discussion. An August 2021 statement from Novavax suggested that a booster shot given 6 months after the second dose provided immunity more than four times stronger than immunity after the first two doses.
In summary, the five most frequently administered COVID-19 vaccines (Moderna, Pfizer-BioNTech, Johnson & Johnson, Oxford-AstraZeneca, and Novavax) have been developed to combat the pandemic, providing effective protection against the virus and its variants. The currently recommended immune protection duration for these vaccines is at least 6 months, with an ideal interval of 12 months between last exposure (infection or vaccination) and the next vaccination to ensure optimal immune response.
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