India extended gap between first, second Covishield vaccination jabs due to vaccine shortage
Senior epidemiologist, Dr Jaiprakash Muliyil said that If India had all the vaccines in the world, the Covid Working Group would have suggested to give the second shot earlier
Members of the Covid Working Group which recommended extension of the gap between first and second doses of Covishield said they did it because there is vaccine shortage in India. Now, two days after the Union health ministry had increased the gap between two doses to 12-16 weeks from eight weeks based on UK real time data, the Boris Johnson-led UK government said the wait between the two doses will be cut to eight weeks for those above 50 because of the concern over the Indian coronavirus variant.
“There is no vaccine. So, whatever vaccine is there, give it to as many people as possible. We will worry about the second dose later. So, we thought it’s better to give one dose now with the proviso that the second dose maybe delayed. Before the second dose comes up, we will have information on breakthrough infections,” explained Dr Jaiprakash Muliyil, a retired professor of Christian Medical College in Vellore and a member of the Covid Working Group.
India has two vaccines – Covishield and Covaxin. “Both of them have an under supply problem. In such times, the only weapon we have is the vaccine. The other is a lockdown, which does not work because people have to go out. If people are vaccinated, there is some protection,” pointed out Muliyil. The two doses of Bharat Biotech’s Covaxin will continue to be administered four-six weeks apart.
“When you don’t have enough vaccines, the question is should you try to give as many people as possible the first dose. We have realised it doesn’t matter if you give the second dose a little late, it doesn’t harm. The response is good. The gap is important,” said Muliyil.
The retired epidemiologist said that If India had all the vaccines in the world, the team would have suggested to give the second shot earlier. “The gap between vaccines does not reduce the inability to cause the booster reaction to the second dose. So, we are saying we can wait up to six months because we don’t have enough vaccines,” said Muliyil.
In UK there is anxiety about the new variant B.1.617.2, a form of the coronavirus variant first identified in India. Fortunately, the new Indian variant still obeys the rule of immunity when it comes to previous infections. “If you are already infected, there are fewer chances of the newer variant attacking you. The new virus is practically infecting previously uninfected people,” maintained Muliyil. The new variant is not very different from the old virus, except that it is more infectious; it is not more virulent.
The Covid Working group is chaired by Dr NK Arora of INCLEN Trust and has Dr Rakesh Agarwal, director and dean of JIPMER, Dr Gagandeep Kang of Christian Medical College, Dr Navin Khanna, group leader of International Centre for Genetic Engineering and Biotechnology, Dr Amulya Panda, director of National Institute of Immunology and Dr VG Somani, the Drug Controller General of India, as it other members. The recommendation of this team was accepted by the National Expert Group on Vaccine Administration for Covid-19 headed by Dr VK Paul, Niti Aayog member.
Arora underlined that they did not plan to blindly follow UK. “They have decided to reduce the interval and we have decided to increase the interval because we saw the results they had presented. Our objective is to provide maximum protection to maximum people,” said Arora.
Two weeks ago, the Public Health Agency of England had published data, which showed that if the interval between Covishield jabs is three months, then the protection is between 65%-85%.
“We wanted to take benefit of it. For three months, we did not increase the duration between shots, because we were not convinced of the data which was published as part of the trial. We started with four weeks, then increased to eight weeks and then UK published data showing good efficacy if there is increased time between shots,” explained Arora. He added that he doesn’t know why UK is fearful of the new variant B.1.617. Detailing the numbers, Arora said India would save only five crore doses by extending the interval between the two doses and that doesn’t change much for a country of India’s size.
Muliyil stressed that in the case of Covid, the virus is an extremely “antigenic one, in other words it is an immunogenic”. “The vaccines have used the same antigen to induce the same response. The real answer to vaccination is not the antibody response but the T-cell response,” underscored Muliyil.
Like B cells, which produce antibodies, T cells are central players in the immune response to viral infection. When SARS-CoV-2 virus, which causes COVID-19, replicates inside cells, T cells, along with other cells, drive the response which kills those cells infected with the virus.
“What we have seen with the vaccination is that T-cells are warned and the next time the disease comes around, there is a quicker response to the virus. That is why even though a patient contract the virus, but the seriousness of the disease is curtailed. Deaths are curtailed. The antibody levels are important in certain diseases such as Tetanus, but here it is not that. Here the important thing is the triggering of T-Cell immunity,” explained Muliyil.
While studying the data for vaccination trials, Muliyil said, they had seen even during Covishield trials that there were breakthrough infections. “This information is not unknown. The breakthrough infection is only the transient colonisation of the throat. People can get infected after vaccination, but not serious infection was seen during trials. Vaccination was to prevent serious disease and not infection,” underscored Muliyil.
The professor said that during the study, the team noticed that the first dose is not different from the second in terms of protective effect. “All this amounts to stating that there is not much difference if you take one dose or two doses. The important thing is to get the vaccine. Once the T-cells learn to deal with this antigen, your T-Cell will learn and fight back. Even in case of the elderly who have comorbidities, antibodies and T-cells do get triggered but rather late. The young people produce it early. So, when we are giving the vaccination, it is to induce an early response,” added Muliyil.
“There is no guarantee that the second dose will make it any better because it is the ability of the T-Cell that matters and not the antibodies. So, even if we don’t have the particular antibody to neutralise the new variant, the T-cell response will be good. It is almost similar to the earlier response. At the moment, the only hope is to vaccinate enough people, even if it is half as protective as the earlier virus. It is good enough,” said Muliyil.
The government is set to review the Covid vaccination data in the next three or four months. “We will look at new data and decide whether there is need to maintain the same interval or come back to four weeks or maybe even a single dose is enough. The data is dynamic, so the situation can change. We are setting up a national vaccine tracking platform to check the effect of vaccination and breakthrough infections,” highlighted Arora.