Moderna is seeking a green light for using its Covid-19 vaccine for teens as young as 12 in the EU, United States and Canada, as Pfizer-BioNTech's shot is already being administed across the regions.
Pfizer is now planning to test its vaccine on children aged between five to 11, while China has approved Sinovac Biotech's shot for emergency use in children as young as three.
However, with many parts of the world still awaiting doses for more vulnerable people, the World Health Organisation is urging wealthy countries to donate their surplus doses to poorer countries instead.
The following is a list of some countries that have approved or are considering vaccinating children:
EU countries
France has started vaccinating those from 12 years upwards, provided they have parental consent.
Germany's vaccine advisory committee recommended on June 10 that only children and adolescents with pre-existing conditions should be given Pfizer's vaccine.
Austria aims to have over 340,000 children aged 12-15 vaccinated by the end of August, according to news site Vindobona.
Estonia could start vaccinating teenagers by the autumn, public broadcaster ERR reported, citing the head of the government's COVID-19 council.
Hungary started vaccinating 16 to 18-year-olds in mid-May, according to Xinhua news agency.
Italy on May 31 approved extending the use of Pfizer's vaccine to 12-15 year olds.
Lithuania's prime minister said the country could start vaccinating children from age 12 in June, news site Delfi reported.
Spain plans to start vaccinating children between 12 and 17 years old around two weeks before the academic year starts in September, the health minister said.
Europe (non-EU)
British ministers will be advised against mass vaccinations of children below 18 until scientists obtain more data on the risks, The Telegraph reported on June 16, though the country's regulator has already approved Pfizer's shot for 12- to 15-year olds.
Switzerland approved on June 4 vaccinating 12 to 15-year-olds with Pfizer's shot, ahead of the country's plan to start inoculating younger people starting as early as July.
Norway may consider the Pfizer vaccine for children who have a high risk of becoming seriously ill with COVID-19, VG newspaper reported.
San Marino has opened vaccinations for children aged 12-15, reported San Marino RTV, citing its Institute for Social Security.
Middle East
Israel launched its innoculation campaign for children aged 12-15 on June 6, The Times of Israel reported, though some health groups were already vaccinating under-16s in at-risk groups.
Dubai has started offering the Pfizer-BioNTech vaccine to 12 to 15-year-olds, after the United Arab Emirates approved the shot for emergency use for the same age group in mid-May.
Asia-Pacific
China on June 5 approved emergency use of Sinovac's vaccine for those between three and 17.
Singapore opened up its vaccination programme to adolescents aged 12-18 from June 1.
Japan on May 28 approved the use of Pfizer's vaccine for those aged 12 and above.
The Philippines on May 26 decided to allow the Pfizer-BioNTech's vaccine for emergency use in children aged 12-15.
Hong Kong will open its COVID-19 vaccine scheme to children over the age of 12, the government said.
Americas
Brazil on June 11 approved use of Pfizer's vaccine for children over 12.
Chile has approved use of Pfizer's vaccine for 12 to 16-year-olds.
US states began inoculating young adolescents in mid-May.
Canada in early May approved use of Pfizer's vaccine for use in children aged 12-15.