The Calcutta Municipal Corporation’s Covid vaccination centres will administer only second doses on Mondays, Wednesdays and Fridays and first doses on other days from next week, Atin Ghosh, who heads the civic body’s health department, said on Friday.

Vaccines are not administered on Sundays.

Senior officials of the civic body said the decision to reserve separate days for the first and second doses was taken to ensure that those whose second doses have become due do not miss out on the shot.

CMC officials in charge of vaccination said they had noticed that nearly 80 per cent of those who had been vaccinated at their centres over the past 10 days were first dose recipients.

“If the trend continues, very soon people whose second dose has become due may complain that they are not getting their shots. We want to prevent that. The decision will ensure equal opportunities to both sets of recipients,” an official said.

What also prompted the civic body to take the decision, the official said, was the fact that the CMC has been getting fewer doses than what it used to in May.

Some of the centres that used to administer 300 or 350 doses each day in May are now administering only 150 a day because of inadequate supply.

Those who took Covishield first dose in May are now eligible for the second dose. “If most of the 150 doses being administered daily go to first dose recipients, the backlog of second dose recipients will keep increasing,” an official said.

“From Monday, our centres will administer only second doses on Mondays, Wednesdays and Fridays. First doses will be administered on Tuesdays, Thursdays and Saturdays,” said Atin Ghosh, a member of the CMC’s board of administrators who is in charge of the health department.

A senior CMC official said about 23 lakh second doses of Covishield are yet to be administered in Calcutta.

“The majority of vaccine doses in Calcutta are being administered from CMC centres. The teaching hospitals and some private hospitals and clinics are also administering the doses. It is unlikely that most of those who have taken their first dose at CMC centres will prefer to take the second dose from other places. So we have to create a situation where these people do not have any difficulty in getting the second dose,” said the official.