Coronavirus vaccine update: We may need a booster shot for COVID-19 vaccine; here’s what it means

Even as the novel coronavirus continues to wreak havoc across the world, the global race for a coronavirus vaccine has also intensified. As of now, more than 150 vaccine candidates are already in different stages of trials and 4 of them have reached the last stage of human testing--the final stage before getting regulatory approvals for licensing of the vaccine. After the encouraging preliminary results of Oxford’s Coronavirus vaccine, there are renewed hopes of a COVID-19 vaccine to be made available before fall 2020.

As the world inches closer to coronavirus vaccine, it is also important to note that we may need more than one dose of the vaccine to battle against the novel contagion. We are talking about the booster dose, which essentially means an additional dose of the vaccine which is given periodically to increase the immune response of the body against a pathogen.

The first approach of developing a vaccine to induce a strong immune response is to introduce live but disabled version of pathogens in the human body. These vaccines are known as the live-attenuated vaccines and they create a natural immune system response against the virus. More often than not just one or two doses of live-attenuated vaccine is enough to provide life long protection against the disease.

As of now, the MMR combined vaccine (Measles, Mumps and Rubella), and vaccines for Rotavirus, Smallpox, Chickenpox and yellow fever are made by disabling the infectious agent of the pathogen.

However, because this type of vaccine contains weakened but live version of the pathogen, it is often recommended that people with a compromised immune system and chronic medical conditions talk to their medical care provider before getting the dose of live-attenuated vaccine.

It should be noted that it may take years of research to develop a safe and effective live-attenuated vaccine. This is precisely why a vaccine developed by using a modified live SARS-CoV-2 may not be the safest approach for the elder population and those with a compromised immune system.

The other kind of vaccine is the inactivated one, which uses a killed version of pathogens to induce an immune system response. However, inactive vaccines do not provide a life long protection against the disease, when compared to the live-attenuated vaccines. This is why a booster dose of these vaccines are given to remind the immune system as the pathogen present in the vaccine is not live.

Following a similar approach, a vaccine candidate being developed by Oxford University uses a part of the spike protein of the novel coronavirus to induce an immune response in the body.

In the case of COVID-19, to get long-lasting immunity against the virus, booster doses may be required after the initial administration of the vaccine. Infact, a lot of experts around the world believe that since COVID-19 outbreaks may become seasonal, they will require similar vaccines (like the flu vaccine) to keep inducing the immune response against the virus.