By Julie Steenhuysen CHICAGO (Reuters) – U.S. officials now say that people 50 and older can get a second COVID-19 booster shot to fortify their immune defenses against COVID-19. But for individuals in that group, the decision is complicated. Here are considerations health experts say people should weigh. WHAT IS THE RECOMMENDATION? Last month, the U.S. Food and Drug Administration and the Centers for Disease Control and Prevention said any person aged 50 and older can get a second COVID-19 booster of an mRNA vaccine from Moderna and Pfizer/BioNTech at least four months following their last sh…