Pfizer/BioNTech and Moderna win U.S. regulatory nod for second booster shot (updated)
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Update: Shortly after the FDA authorization, the U.S. Centers for Disease Control and Prevention (CDC) updated its recommendations allowing certain individuals to receive a second mRNA-based booster shot of Pfizer (NYSE:PFE)/BioNTech (NASDAQ:BNTX) and Moderna (NASDAQ:MRNA) COVID-19 vaccines.
Accordingly, an additional booster shot is indicated for certain immunocompromised individuals and people over the age of 50 after at least four months from their initial booster dose.
In addition, the CDC recommended a second mRNA-based COVID-19 booster at least four months after Johnson & Johnson (JNJ) vaccine recipients completed their primary and booster doses. 
Previously: The U.S. Food and Drug Administration (FDA) authorized a second booster shot of Pfizer (PFE)/BioNTech (BNTX) and Moderna (MRNA) COVID-19 vaccines for those aged 50 years and older on Tuesday.
The FDA clearance allows the use of a fourth dose of mRNA-based vaccines after at least four months from the first booster.
âEmerging evidence suggests that a second booster dose of an mRNA COVID-19 vaccine improves protection against severe COVID-19 and is not associated with new safety concerns,â the FDA said in a statement.
Previously, the FDA had cleared a second booster shot only for those with weaker immune systems. According to the latest announcement, the group can receive an additional booster shot or a fifth shot at least four months after their previous vaccine dose.
The immunocompromised people aged 12 years and above are eligible for a Pfizer (PFE)/BioNTech (BNTX) booster shot, while a Moderna (MRNA) booster is indicated for those aged 18 years of age and older.
Earlier, Pfizer (PFE)/ BioNTech (BNTX) sought FDA nod for a second booster in those aged 65 years and older. Two days later, Moderna (MRNA) filed for authorization of its second booster in adults aged 18 years and above.