Do you need a booster dose to prevent Covid19?
Many countries that have successfully immunised the majority of their adult population must grapple with this quandary of whether or not they should administer a booster shot. Some governments are debating whether to re-vaccinate persons who have already been vaccinated against the extremely dangerous Delta version of SARS-CoV-2, which has been linked to skyrocketing infection rates. Several nations, notably the United Arab Emirates, China, and Russia, have already begun providing further doses of the vaccine, including Germany and Israel.
What is Booster?
It’s another dose of a vaccine you receive on top of the first 2 mandatory doses. The concept is to prolong protective immunity, particularly if there is evidence that protection is waning after a period of time. Most children receive routine vaccinations, including boosters, for illnesses such as chickenpox, tetanus, diphtheria, mumps, measles, and rubella—to name a few. Boosters are recommended because you need the extra doses to get longer lasting protective immunity.
There is also a technical distinction between the terms “third dose” and “booster.” Doctors use the term third dose when referring to people with compromised immune systems who may not have gotten the level of protection they need from the first two doses. The third dose provides that level of immunity.
A booster shot is recommended due to concern that the effectiveness of the vaccine decreases over time and may not protect against a new strain, such as Delta. A booster may be given to older people or those with chronic medical conditions or other risk factors.
Why do you need a booster?
There is an initial increase in the number of immune cells that create antibodies and other chemicals, which then gradually decreases after vaccinations. ‘Memory’ B and T cells are left in the body to keep an eye out for future infections caused by the same virus. A booster does numerous things to these cells.
It encourages antibody-producing B cells to proliferate, re-increasing antibody levels against the infection. Their numbers will eventually drop, but the pool of memory B cells left behind will be higher than before, resulting in a faster, more powerful response to subsequent encounters. Affinity maturation is a process in which ‘engaged’ B lymphocytes — those that have been stimulated by the vaccination — migrate to the lymph nodes. They get alterations here, which makes the antibodies they make attach to pathogens more tightly, perhaps increasing their potency.
With repeated boosting (or reinfection), the number of memory B cells and antibody levels will ultimately plateau, although such levels are unlikely to be attained in persons who have received the recommended COVID-19 vaccination regimen or a previous infection. Stronger immune responses should be elicited by a booster injection.