A healthcare worker gives a dose of the COVISHIELD vaccine against the coronavirus disease (COVID-19), manufactured by Serum Institute of India, to a man as others decorate the vaccination centre to celebrate the milestone of administering one billion COVID-19 vaccine doses, in Ahmedabad, India, October 21, 2021.

NEW DELHI, Oct 21 (Reuters) - India celebrated the milestone of administering 1 billion COVID-19 vaccine doses on Thursday, with the government promoting the achievement in song and video even as a recent drop in inoculations worries healthcare providers.

COVAX partner UNICEF also congratulated India and said it looked forward to "hearing details about the expected timeline and volumes of supplies to be made" to the global facility.

Reuters has reported that India has delayed supplies of the AstraZeneca vaccine to COVAX.