India's top committee on coronavirus disease (Covid-19) vaccines has increased the interval between administering two doses of Covishield to four to eight weeks, from the existing four to six weeks, to increase the efficacy of the vaccine, said Union ministry of health and family welfare in a statement on Monday.
"In view of the emerging scientific evidence, the interval between two doses of a specific Covid-19 vaccine i.e. Covishield, has been revisited by National Technical Advisory Group on Immunization (NTAGI) and subsequently by National Expert Group on Vaccine Administration for Covid-19 (NEGVAC) in its 20th meeting. During this meeting the recommendation has been revised to provide 2nd dose of Covishield at 4-8 weeks' interval after the 1st dose, instead of earlier practiced interval of 4-6 weeks," said the health ministry statement.
However, the Indian health ministry also emphasised that this decision of revised time interval between two doses was applicable only to Covishield, the Oxford-AstraZeneca vaccine locally manufactured by Serum Institute of India (SII), and not Covaxin, that is co-developed by Bharat Biotech and the Indian Council of Medical Research.
Union health secretary, Rajesh Bhushan, on Monday, communicated the recommendation of the expert committee to the chief secretaries of all States and Union Territories. "…he has noted that the Ministry of Health and Family Welfare, Government of India has accepted the recommendations of NTAGI and NEGVAC and has thereafter advised the States and UTs to ensure the administration of 2nd dose of Covishield to beneficiaries within this stipulated time interval of 4-8 weeks after 1st dose," the letter read.
"Keeping the existing scientific evidence in view, it appears that protection is enhanced if the second dose of Covishield is administered between 6-8 weeks, but not later than stipulated period of 8 weeks," it added.
Bhushan also urged the states to instruct the officials concerned accordingly, to undertake necessary steps to widely disseminate the message of revised dosing interval amongst programme managers, vaccinators and recipients of Covishield vaccine, and ensure adherence to the revised dosing interval for maximum efficacy.