MUMBAI: Vaccination against COVID-19 in Mumbai will have to be suspended for the next two days if enough fresh stock is not provided, a civic official warned on Thursday.

The city is witnessing long queues of those above 45 at vaccination centres while a senior official indicated that the drive for the 18-44 age group may not start on May 1 due to the shortage of doses.

"We were told on Wednesday night that we would get around 75,000 vials of vaccine.

With such a low supply, the BMC opened only some vaccination centres while others were kept closed," said Suresh Kakani, additional commissioner of the Brihanmumbai Municipal Corporation.

"Out of the total stock, we have used up some 50,000 vials till this evening.

If we do not get more doses, we will have to suspend the vaccination drive," he told reporters.

As per the Maharashtra Health Department, only 26,610 people received the jab in the country's financial capital on Wednesday.

"If we do not get enough supplies, we will suspend the drive for a couple of days and wait for sufficient stock so that we can aggressively resume inoculation," Kakani added.

Long lines were seen outside vaccination centres in the city during the day.

Though the vaccination begins at 12 noon, at several centres people queue up from as early as six in the morning, said an official.

The civic body has now allowed eligible persons to walk in at vaccination centres without registering themselves on the Co-WIN app.

This also added to the rush.

"Limited supply is one reason for long queues. Earlier people hesitated to get the jab. But with growing number of COVID-19 deaths, there has been a surge at vaccination centres," the official said.

Many people complained that they could not receive the dose.

"We have been standing here for more than three hours but the queue is not moving at all. We are not sure whether we will get a dose today," said 54-year-old Smriti Bindra at the Nesco vaccination centre in Goregaon.

Senior citizens need not stand in long queues as vaccine is in short supply "only for now", tweeted additional municipal commissioner Ashwini Bhide.

"But be rest assured that all 45 plus years citizens will eventually get vaccinated," she added.

The IAS official also said that vaccination for the new age group "will start only after enough vaccines are made available and not exactly on 1st May", so it will not affect the ongoing drive.

Those who have taken their first dose are "reasonably protected" and should not panic if there is a slight delay in getting the second dose, Bhide said, asking people to take precautionary measures such as double masking and social distancing.