As the coronavirus’ Omicron variant spreads across countries like wildfire, there is growing clamour for a vaccine booster dose to improve immunity that may have waned over time. Most Covid-19 vaccines are administered in two doses, while a few are given as a single dose.
A booster shot is an additional dose administered once the protection provided by the original shot(s) begins to decrease over time to maintain longer immunity. While India has not made any decision on administering booster doses, countries such as the United States and Israel have already asked citizens to get the additional doses.
All approved Covid-19 vaccines, barring the one produced by Johnson & Johnson, are administered in two does. Additional vaccine doses after the administration of the first two doses are known as booster shots.
Are booster doses useful?
vaccine-generated immunity is not permanent and wanes after some time, making people vulnerable to the virus. It is still unclear how long the immunity generated by vaccine doses lasts. Experts suggest that the vaccines currently available in the market offer immunity for six to nine months. Booster doses can increase this immunity for a longer period.
Booster dose and Omicron variant
The coronavirus’ Omicron variant has shown signs of evading vaccine-generated immunity, even among those who have been administered the shot recently. However, a number of studies have shown that booster doses offered increased protection against the variant, first detected last month in South Africa.
Why does booster dose offer better protection?
According to health experts, immunity functions like memory. While the effectiveness wanes over time, the memory doesn’t. Apart from extending the effectiveness of the immunity, the booster does also improve the quality of immunity. As a result, the immunity generated after a booster shot is much more effective than the one generated after the regular vaccine doses.