Nov 22 (Reuters) - Pfizer Inc (PFE.N) said on Monday its COVID-19 vaccine provided strong long-term protection against the virus in a late-stage study conducted among adolescents aged 12 to 15 years. A two-dose series of the vaccine was 100% effective against COVID-19, measured seven days through over four months after the second dose, the company said.The long-term data will support planned submissions for full-regulatory approval of the vaccine in the age group in the United States and worldwide. Pfizer and BioNTech (22UAy.DE) will seek clearance for a 30 micrograms dose of the vaccine for those aged 12 and above. The vaccine was authorized for emergency use in people aged 12-15 years by the U.S. Food & Drug Administration in May, and granted full approval for use in people aged 16 and above in August.