BENGALURU: The Centre’s advisory to states to extend the interval between the first and second doses of Covishield vaccine to 12-16 weeks from the earlier 6-8 weeks has left many senior citizens confused. Those who took the second dose after six weeks are now concerned about its efficacy.
“We took the second dose in 6-8 weeks but the latest advisory suggesting an interval of 12-16 weeks has left us confused,” said Sridhar MS, 61, from Bengaluru.
Dr T Jacob John, retired professor and head of clinical virology and microbiology at Christian Medical College, Vellore, said there isabsolutely no problem if the second dose of Covishield is delayed.
“The protection it offers after a four-week interval is nearly 100% against a severe form of the disease,” he explained. “But it is not 100% against mild and moderate Covid. If you increase the interval up to 12 weeks, the efficacy against mild to moderate disease increases.”
Dr John conceded no study has been conducted to test efficacy beyond a 12-week window. “What is known so far with all vaccines is that even if you delay the second dose by a year, the first dose is still effective. Given the situation, a four-week interval is ideal. But if there is a problem with supply, is it better to delay it so more people get the first dose,” he said. “If someone has missed the second dose of Covaxin, it can be taken within a year as well,” he said.