After recognizing that the ChAdOx1 nCoV-19 (Oxford/AstraZeneca) vaccine caused rare but severe adverse reactions, European health authorities recommended that people younger than 55 years should switch to the BNT162b2 (Pfizer-BioNTech) vaccine for their second dose. A study published in Nature found the combination to be more effective and immunogenic than the standard BNT162b2 […]