Several states have sought the Centre’s directions in this regard, said health ministry officials. The National Technical Advisory Group on Immunisation will have to weigh in, they said, as it is not clear how long immunity lasts after vaccination.
“While there is evidence that immunity from a Covid-19 infection can last eight months or more, there is no concrete scientific data on immunity acquired through vaccination,” said a health ministry official.”There is also a more complex issue, of which booster dose to administer. If a healthcare worker had received Covaxin, should he or she be given a booster shot of Covishield or vice versa?”
‘For dose forecast exercise’
States such as Haryana and Chhattisgarh have raised the issue formally with the Centre to ascertain whether there should be a change in protocol for healthcare workers who had received both doses of the vaccine by February-end.
“We have written to the health ministry and NEGVAC (National Expert Group on Vaccine Administration for Covid-19), seeking clarity on whether our healthcare workers, who completed the vaccine protocol in the first months, need a booster dose,” Haryana’s additional chief secretary (health) Rajeev Arora told ET.
“In case they do, we would need to understand how many doses would be required and we would include that in our dose forecasting exercise.”
Haryana has also raised with the NEGVAC the issue of mixing of doses.
Chhattisgarh has also raised the issue in meetings with central government officials. State health minister TS Singh Deo said, “The issue of a booster dose is under study by scientists and there is a view that a third booster dose of Covishield is very effective. It needs to be seen whether it is a sales pitch or based on reliable scientific research. We have sought clarity on this.”
According to the Indian Council of Medical Research (ICMR), the immune response following a Covid-19 infection can last seven to 12 months. When asked about the need for a booster dose of Covaxin, ICMR director general Balram Bhargava said on Tuesday, “This is still in scientific ideation stage.”
Meanwhile, joint secretary (health) Lav Aggarwal said the Centre’s priority at present is to inoculate priority groups with both doses of Covid-19 vaccine.