Chaos reigned outside many Covid vaccination centres of the Calcutta Municipal Corporation on Tuesday as far fewer doses were available than the number of people waiting for the jab.

In the evening, the state health department announced that half the available doses would be reserved for second dose recipients till the supply improved.

Police had to rush to many of the vaccination centres to control the situation as people who stood in the queue for five hours or more vent their anger after being told that no more doses were available.

Civic officials said each ward health clinic received only 50 doses on an average. This was way short of the demand. At some of the centres, as many as 350 second-dose recipients had turned up for the jab. In addition, there were many waiting to get their first dose.

“The police had to be sent to many vaccination centres. One of those was in Kasba and another in Netaji Nagar. At both centres, there were at least 350 second-dose recipients. They had queued up since the morning. They got very angry when we put out a notice that only 40 to 50 doses were available,” said a CMC official who is responsible for managing vaccination in many wards.

“Some of them kept asking, ‘will we ever get our second dose?’ We had no answer,” said the official.

Queues at vaccination centres had reduced considerably after the Centre increased the gap between two doses of Covishield from six-eight weeks to 12-16 weeks. The rush has since resumed as the second dose has become due for many Covishield recipients.

Vaccine supply, however, is still very low.

Ajay Chakraborty, the state’s director of health services, said on Tuesday evening that “due to acute shortage of vaccines, second dose will be given priority till we receive adequate” supplies.

The state’s central store had only 6 lakh doses left on Tuesday, he said.

An order issued by the health department said: “It is now decided that at least 50 per cent doses should be assigned for second dose on daily basis. This formula may continue till further order.”

The order also says: “It is clear that the number of due/overdue vaccines is growing rapidly. It is imperative on the administration to provide second dose to all such persons without delays.”

The order also mentioned that 637,263 second doses were due till July 31 in Calcutta alone. These people had taken their first dose of Covishield or Covaxin between April 1 and May 7. The corresponding figure for the entire state was 37,93,640.

CMC officials said the situation was unlikely to improve soon.

If only 50 doses are allotted to a clinic daily, the number of those due for the second dose will keep mounting. “Very soon we will have to stop administering the first dose altogether,” an official said.