Amid criticism on increasing the duration of the second dose of Covishield, a member of the group that recommended the huge change said that the decision was based on science and not vaccine shortage. Comparing the benefits of increasing the duration, the government has launched a detailed study to compare the benefits, said NK Arora, chairman of the Covid working group.
On Thursday, the government announced that the gap between two shots of Covishield should be 12 to 16 weeks- earlier, which was six to eight weeks.
A member of the National Technical Advisory Group on Immunization, Dr Arora, rejected speculation that the decision was spurred by vaccine shortage that has halted inoculations of those between 18 and 44 in parts of the country, NDTV reported.
“If I increase the gap by one month, then what difference will it make? It will make a difference of about four to six crore doses. So giving the second dose after a month is hardly going to address vaccine shortage. Increasing the gap is beneficial," he added.
He further emphasised that scientific data states that if the second dose of the Oxford AstraZeneca vaccine- officially known as Covishield in India was given after three months of the first dosage then the chances of protection from infection is 65 to 88 per cent.
“Initial studies on the vaccine had even talked about a 44-week gap. Canada has made it four months," he added.
He also stated that the antibodies to fight the virus increased substantially after the second dose, but the degree of their impact was not yet known. “But data shows if the gap is increased, the antibodies increase by 40 to 50 per cent," he added.
Addressing concerns of people who stated that they have taken shots within a one-two month gap, he said that “those who have taken the shots within a one or two month gap do not need to worry and the production of antibodies will be good."
On comparing the effectiveness of the vaccine for a 28-day gap, a four-six week gap or 12-16 week gap, Dr Arora said there was no data so far but the government had planned a study.
“How much protection will increasing the gap give? How much will it protect from the severity of infection or death? In the next four weeks, data of this study will start coming and will be released in regular bulletins," he disclosed.
So far, the data has revealed a 0.02 to 0.04 per cent chance of reinfection after both doses, and the chances of a severe infection or death were “very rare", he said.
According to him, around 95 per cent of adverse effects after full vaccination were mild and only a fraction was severe. “But our data has shortcomings. Most adverse impact cases are reported only in the first three-four days. We have asked for data on problems experienced even after 28 days."
Taking cognizance of cases of death in patients who had administered both the dosages, Dr Arora told NDTV these were still being examined and they have to see whether those are from Covid or from the vaccine.
“We don’t know much about Covaxin yet but from international reports, we know that there can be problems four to 20 days after a Covishield shot. There could be clotting or bleeding. We haven’t seen this problem here so much, only about 0.61 per cent. About six persons in a crore can experience clotting or bleeding. That is far less than European numbers," he added, asserting that the vaccines were completely safe.
Responding to the query on door-to-door vaccinations, Dr Arora said that the reason why door-to-door vaccinations had not been allowed was that in case of a severe allergic reaction if there was no immediate treatment, it could cause death.