COVID-19 vaccines are not infection-preventing but disease-modifier vaccines, said Samiran Panda, member of the government’s National Expert Group on Vaccine Administration for Covid-19 (NEGVAC). Dr. Panda was speaking to The Hindu on apprehensions about using a vaccine that isn’t 100% effective in disease prevention.
He said both the vaccines now available in India now will prevent the asymptomatic stage from moving into symptomatic stage and from symptomatic stage to developing severe disease where one requires intensive care. The vaccines also help in reducing the number of deaths significantly, he noted.
“Scientifically, it is proven that the efficacy of both the vaccines available in India is more than 70-80% . The World Health Organisation recommends that any vaccine with a 50% efficacy will be useful in a pandemic time. So, people should not be hesitant about taking the vaccine,” said Director General of the Council of Scientific and Industrial Research (CSIR) Shekhar Mande.
Dr. Mande further explained that there have been odd cases of people developing COVID after vaccination.
“There could be two explanations for this. One that these could be people who fall into those 20-30% groups who don’t get protection through a vaccine and second, these people develop an infection but the intensity of the infection remains lower. We have seen a significant reduction in hospitalisation and mortality among vaccinated people,” he said.
Speaking about how long the immunity lasts with the two vaccines available, Dr Mande said that as of now there are two types of immunity — humoral and cell-mediated. “Humoral immunity involves antibodies secreted in the blood. Since the pandemic is only 15 months old, there is no actual data on how long the antibodies remain in the blood,” he said.
Dr. Mande added that presumptions are that though the humoral immunity may last a few months, the cell-mediated immunity may last longer. And that’s an equally effective arm of the immune system to fight the infection.
Indian Medical Association member Rajeev Jayadevan said, “Currently we do not have published evidence on the duration of protection these vaccines offer. However the lack of published papers about duration of protection of vaccines is not to be interpreted as that vaccine protection is short.”
An effective vaccine lowers the chance of getting the disease if the person encounters the virus and all the currently authorised vaccines are highly efficacious at preventing serious illness, hospitalization and death, said Rajiv Dasgupta, member, government’s National Adverse Effects Following Immunization Committee.
He added that based on the real-world experience, the vaccine is effective for at least six months.
“At this point the duration of full protection is unknown but booster doses are likely to be necessary; it is still not clear though whether it'll be an annual vaccination like the flu shots. COVID-19 vaccines in adults, as per the current evidence, do not prevent the disease in 100% of the recipients and the full benefits come into play two weeks after the second dose,” he said.
N.K Arora, head of the operations research group of the Indian Council of Medical Research’s National Task Force for COVID-19 noted that “vaccine coupled with COVID appropriate behavior is the way forward.”
Warning that not getting vaccinated puts people at a disadvantage in the future, Director of the Centre for Cellular and Molecular Biology Rakesh Mishra, said right now the available vaccines work on the variants of COVID, “but if we don’t get ahead of the virus, mutations will continue and we may arrive at a stage that the mutations no longer respond to the available vaccines”.
Meanwhile, speaking about why the government isn’t opening up vaccination for all adults, Dr. Panda said the government’s decision to give vaccines to all above 45 years of age is a well-thought out move.
“The idea was to first cover those who are at higher risk of catching the infection — our healthcare workers who were treating the sick; the frontline workers, who were managing the other aspect of COVID care and then the government included the elderly and people with comorbidities, who are at a higher risk of developing severe disease and mortality,” he said.
