To get or not to get booster vaccine for Covid-19
Anika H. Ahmed, MD
As pharmaceutical staff continues to work round the clock, conducting clinical trails, collecting data, circulating questionnaires and surveys, they have been successful in bringing out the booster shots for protective vaccination against the highly infectious, often deadly Coronavirus causing the global pandemic of Covid-19. Public now has multiple choices in relevant vaccination against Covid-19, with pharmaceutical companies like Pfizer, Moderna, Johnson & Johnson, and Sinopharm taking the lead.
The most amazing feature of the human immune system is that it has an immunological memory of past infections or vaccines. Any time the immune system is exposed to an infection or a vaccine, which is basically an attenuated form of the virus or bacteria, it can trigger an antibody response of the immune system, hence keeping the body protected. However, it is normal for the virus fighting antibodies, such as those that are stimulated by a Covid-19 vaccine to wear out over time. Research indicates that these protective antibodies remain high for six months after the second dose of the vaccine and then wane over time. One way of measuring vaccine efficacy is to measure the antibody levels in the blood, and this has led scientists to repeatedly find a decline in the antibody levels, among vaccinated individuals, six months after the second dose of mainly Pfizer or Moderna Covid-19 vaccine.
Booster Covid-19 vaccine shots cash on the unique feature of the immune system to have a remarkable immunological memory of past vaccines. In people getting booster shots of Covid-19 vaccine, the memory response of the immune system is even more vigorous than the original response to earlier vaccination. This is why some people may experience more severe side effects, lasting for a longer time period, but with full recovery in 24-48 hours. This memory response of the immune system not only includes antibody response, but also includes an additional arm of the immune system controlled by a different group of white blood cells called T cells or T lymphocytes. T cells immune response are especially important for viral infections like Coronavirus, as they have proven to be just as important as antibody response, in protecting against infection and preventing serious complications requiring hospitalization.
If there are limited supplies, both FDA and CDC do support a mix and match approach of booster shots, with one booster dose of Pfizer given after a Moderna first and second dose or vice versa. However, if the supplies last, the current public health recommendations are that people should stick to one type of mRNA vaccine for all doses of vaccination, maintain an immunization record card and be ready for more booster shots as new variants make an appearance that may not be covered by the previous shots of vaccines.