SATARA/BHUBANESWAR -- India’s COVID-19 vaccination drive hit a bump on the first day due to glitches in an app called Co-Win that is being used to coordinate the campaign, according to several officials involved in the immunisation programme.

Prime Minister Narendra Modi launched what his government has described as the “world’s largest vaccination programme” on Saturday to rein in the pandemic in India, which has reported the second highest number of cases after the United States.

Co-Win, developed by the government, is supposed to help by alerting healthcare workers who are first in line to get shots, and by allowing officials monitor and manage the entire drive.

But many health workers, who were to receive the vaccines, did not get the message on Saturday, said a senior official with the health department of the western state of Maharashtra.

“We were planning to vaccinate 28,500 people on Saturday but could do only 18,328 because of glitches in the Co-Win app,” the official told Reuters on condition on anonymity as the details are not public yet.

Maharashtra, home to the financial hub of Mumbai, has been hit the hardest by coronavirus among all Indian states.

India was aiming to vaccinate more than 300,000 people on day one, but only 191,181 people were inoculated on Saturday, official data shows.

In the eastern state of Odisha, officials said they were forced to use printouts due to issues with the app.

“We also went with our plan B and contacted people to be vaccinated directly offline,” Bijay Kumar Mohapatra, Director, Health Services, Odisha, told Reuters.

The Indian government did not respond to a request for comment on Sunday.

“The system performance and speed was improved and is being further optimised,” Manohar Agnani, additional secretary, ministry of health and family welfare, said on Saturday.