How long does immunity last after vaccination, will the third dose be needed?


Scientists worldwide are trying to find out how long a person who has been cured of the Coronavirus and who has been vaccinated has immunity against this epidemic.

Efforts are also being made to determine if a third dose of the vaccine (booster shot) be required for immunity.

So far, no concrete information has been found in this direction, but some early indications have begun to appear.

The situation is not clear regarding the time of the third dose

Based on the information so far, it is being said that a third dose (vaccine dose to increase antibodies) will be needed shortly after the vaccine is applied, but it is not yet clear when it will be needed.

Dr Peter Marks, director of the US Food and Drug Administration’s Center for Biologics Evaluation and Research, said, “A third dose will be needed. I think a normal adult may need to take this dose a year after the vaccine was applied.”

Immunity is detected with antibodies.

Immunity against a disease can be achieved after a vaccine or recovery from that disease.

Actually, after being cured of vaccination or disease, antibodies are formed in the human body against the disease, protecting the person from getting sick again.

The presence of antibodies usually measures immunity, but antibodies and T-cells are necessary for the body to fight disease.

Companies studying immunity

Several vaccine makers, including Pfizer and Moderna, are investigating the possible use of the third dose.

These companies are studying whether the vaccine immunity will disappear after some time and whether their vaccine will protect against new variants of the corona.

Therefore, people who have been vaccinated may also have to take the third dose to protect against new variants.

A booster shot is needed for many diseases.

If a third dose is needed against the corona, it will be the same, as it is advisable to get tetanus vaccinated every ten years. Or vaccines are given every year to prevent any other diseases.

Vaccines made for measles and smallpox provide life-long protection, but not in the case of influenza and coronavirus. Frequent mutations in them are the primary reason for this.

Natural immunity lasts for about a year.

According to a study published in the journal Nature on Monday, researchers found that immune cells present in the bone marrow of corona-infected individuals may have a ‘memory’ of the infection for a long time (about 11–12 months). Similarly, another study published in the journal EClinicalMedicine showed that antibodies against the coronavirus were detected even ten months later in individuals recovering from the epidemic.

The third dose is also being considered in India.

This week the Indian government said it was considering a third dose. Dr VK Paul, the head of the country’s Corona Task Force and a member of the NITI Aayog, said no vaccine could provide 100 per cent protection against corona infection. Therefore, trials are being conducted regarding the need for booster shots to increase the protection against viruses. He said that people would be informed about this when needed.


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