NEW YORK (REUTERS) - Pfizer Inc said on Friday (Jan 22) it had finished enrolling children aged between 12 and 15 in a study testing its Covid-19 vaccine, as the US drugmaker seeks to expand the shot's use among different age groups.

The study, which was announced in October, had enrolled over 2,000 participants, a Pfizer spokeswoman said in an e-mailed statement.

Vaccines from Pfizer and Moderna Inc, which are being rolled out in the United States, are not yet available for use in children due to a lack of study data.

Children rarely experience severe Covid-19 symptoms but they could still spread the virus.

Last month, Moderna also began a study to test its vaccine, which uses a similar technology as the Pfizer vaccine, in adolescents aged 12 to less than 18.