India on Monday began administering precautionary third doses of the Covid-19 vaccine to healthcare and frontline workers, and senior citizens with co-morbidities.

In Tamil Nadu and Karnataka, the chief ministers of the respective states MK Stalin and Basavaraj Bommai attended programmes to mark the beginning of the new phase of the vaccination drive.

The administration of booster doses to senior citizens, healthcare workers and frontline workers also began in Delhi and Mumbai, which have reported very high Covid-19 numbers in the past two weeks.

The booster dose of the vaccine will be given to people who received their second dose at least nine months or 39 weeks earlier, ANI reported. The CoWin portal will send SMSs to people to take the booster dose when they become eligible for it.

Union Health Minister Mansukh Mandaviya said on Sunday that such SMSs have been sent to over 1 crore eligible persons.

On Sunday, Prime Minister Narendra Modi chaired a high-level meeting to assess the Covid-19 situation in the country. During the meeting, he said that vaccination coverage the precaution dose should be taken up in a mission mode, according to a press release.

The Union health ministry said on Friday that there is no need to make a new registration on the CoWin portal to register for booster doses, the Hindustan Times reported. Beneficiaries can also walk into vaccination centres to get the precautionary dose.

The Centre has also stated that it will not mix coronavirus vaccines when administering booster doses. This means that those who received primary doses of Covishield will get the same vaccine as a booster dose, and likewise for Covaxin.

On December 25, Prime Minister Narendra Modi announced that India’s vaccination programme will be opened to children over the age of 15 from January 3. He also said that a “precautionary dose” would be administered to healthcare workers and those over 60 years with co-morbidities from January 10.

On January 3, Covid-19 vaccination for children began across the country.

Healthcare workers, frontline workers and senior citizens have begun getting their booster doses amid a sharp rise in Covid-19 cases across the country. India on Sunday reported 1,79.339 new Covid-19 cases.

Meanwhile, the Indian Council of Medical Research cited a pre-print study to say that a third dose of Bharat Biotech’s Covaxin “hold promise”.

The study showed that the third dose produced good levels of antibodies and no serious adverse events were reported.