India has begun administering booster doses of Covid-19 vaccine to frontline workers and vulnerable elderly people, with the fast-spreading Omicron variant fuelling an almost eight-fold rise in daily infections since the start of the year.

India reported 179,723 new cases , most of them in the country's biggest cities — Delhi, Mumbai and Kolkata — where Omicron has overtaken Delta as the most prevalent strain of the virus, according to Reuters.

There were 146 deaths reported, bringing the toll to 483,936 since the pandemic first struck India in early 2020.

Facing this rising third wave of infections, the government sent booster reminders to more than 10 million people who took their second dose of the Covaxin or Covishield shot nine months ago.