By Dr Sandeep Patil, Chief Intensivist, Fortis Hospital Kalyan ~
During the early days of pandemic, it was unclear how individuals would develop protective and lasting immunity against SARS-CoV-2. People lived in a limbo of whether they would gain immunity after infection or vaccination. Therefore, the initial focus was on understanding and defining virus neutralising antibodies from B cells after infection. Early reports indicated that such antibodies decline substantially over less than six months. This raised questions about how long protective immunity might last following an infection.
T-cells known to be important in protecting against infections through processes like cellular immunity, were also considered in research work. Later, defining the roles of T cells in COVID-19 became a central focus for all investigations. Continuous scientific investigations determined that both memory T-cell and B-cell responses specific to SARS-CoV-2 on an average for 3 months. Similar T and B cell responses might be expected following vaccination, and may account for the good efficacy, as suggested by interim results from the three most advanced vaccine candidates, indicating a clear chance of populations to develop vaccine induced immunity.
SO HOW DO WE ACHIEVE VACCINE INDUCED IMMUNITY?
As many experts suggest, vaccination has become a critical addition to our defenses against COVID-19—this much is certain. But our ability to achieve vaccination-induce herd immunity is still unknown. While that shouldn’t stop us, it also shouldn’t stop us from practicing safety guidelines that can curb the disease. If COVID-19 is a raging forest fire, then vaccines are the firefighters trying to quell it. We have to continue with the preventive measures—social distancing, mask wearing, hand hygiene, and rapid testing.
World Health Organization (WHO) estimates that 65-70% of a given population must get vaccine to halt the spread of disease. After that, the COVID-19 virus will have few human hosts to choose from, driving down transmission rates dramatically. The process of getting there is simple theory, but laborious and time-consuming in practice. However, we cannot stop trying as I mentioned earlier.
VACCINATION SAFETY: IMMUNE SYSTEM AND HOW IT WORKS?
Some concerns about vaccine safety relate to how vaccines interact with the immune system, or even how the immune system functions in different situations (e.g., natural infection versus immunization). While it is fair to consider these concerns, it is important to understand them in the context of how the immune system works. It is true that natural infection causes better immunity than vaccines. However, the difference between vaccination and natural infection is the price for immunity. Do we need to find for proactive solutions? Immunization with vaccines, like natural infections, induces long-term immunity. And moreover, the vaccine candidates that have received approval from regulatory authorities are efficacious and safe. Speak to your doctor today if you have more doubts.
