The Centre is considering a COVID vaccine booster shot for all those above 18 years in view of a surge in coronavirus infections in parts of the world and also to ease difficulties faced during international travel, sources said on March 21.

Currently, healthcare and frontline workers and those above 60 years are being administered the precaution doses of the COVID vaccine. All people above 60 years have become eligible for this dose after the Union Health Ministry removed the co-morbidity clause recently.

The prioritisation and sequencing of the dose are based on the completion of nine months, or 39 weeks, from the date of administration of the second dose. "The government is considering a booster dose of COVID vaccine for all those above 18 years in view of a surge in infections in parts of the world and to ease difficulties faced during international travel," a source said.

Amid a growing chorus for booster doses by several states, Rajya Sabha MP also raised the issue in the Rajya Sabha and asked the government to come out with clear guidelines for boosters for those under 60 years, noting that several countries are imposing strict conditions for foreign travellers.

The MP said several countries want that the second shot of the COVID vaccine should have been taken within a certain time frame, failing which the vaccination certificate will not be considered valid. In many European countries, she said, vaccines are considered valid only for 270 days. If travellers got their last vaccine shot in April 2021, they cannot enter many EU countries without a valid COVID test.

"Hence, Indians finally looking forward to travelling abroad are now left in a lurch due to the absence of clear guidelines regarding the need for the third additional dose to travel abroad. The present situation regarding the travel and vaccination causes of the perplexing situation for Indians," she said during Zero Hour.

India now has a surplus of vaccines yet there is no clear guideline to vaccinate people below 60 years for those who are seeking a booster dose for travel purposes or for safety purposes, the Rajya Sabha MP added.

White House Chief Medical Advisor Dr Anthony Fauci, meanwhile, said that vaccines and booster shots remain the best means to prevent serious illness from the virus. Fauci also warned that a highly contagious sub-variant of Omicron variant of COVID -19, known as BA.2, could soon lead to another uptick in coronavirus cases in the US.

The US' top infectious disease expert said the sub-variant is estimated to account for around 30 per cent of all new cases in the US and is also the most dominant variant in the country. Fauci said BA.2 is about 60 per cent more transmissible than Omicron, but it does not appear to be more severe.

It does have an increased transmission capability, Fauci said on Sunday on ABC's This Week. However, when you look at the cases, they do not appear to be any more severe and they do not appear to evade immune responses either from vaccines or prior infections, he explained.

The variant has already caused a surge in cases in China and parts of Europe. India began administering precaution doses of the COVID vaccine to healthcare and frontline workers and those aged 60 and above with co-morbidities from January 10 this year.

Since January 10, more than 2.17 crore precaution doses have been administered to the identified categories of beneficiaries so far. COVID -19 vaccination for children in the age group of 12-14 years began on March 16 this year.

The countrywide vaccination drive was rolled out on January 16, 2021, with healthcare workers getting inoculated in the first phase. Vaccination of frontline workers started on February 2 last year. The next phase of COVID -19 vaccination commenced on March 1 last year for people over 60 years of age and those aged 45 and above with specified co-morbid conditions.

India launched vaccination for all people aged more than 45 years from April 1, 2021. The government then decided to expand its vaccination drive by allowing everyone above 18 years of age to be inoculated against the viral disease from May 1, 2021. The next phase of COVID vaccination commenced from January 3 this year for adolescents in the age group of 15-18 years.