The Food and Drug Administration on Tuesday authorized a second booster of Pfizer-BioNTech and Moderna for adults 50 years and older, announcing that a fourth shot improves protection against severe Covid-19. The agency also authorized a second Pfizer-BioNTech booster for immunocompromised children older than 12 and a second Moderna booster for immunocompromised adults over 18 […] Read the full story on GreekReporter.com.