A booster dose of Johnson & Johnson’s vaccine performed well in terms of protecting against hospitalization in people who contracted COVID-19 in South Africa, according to a study published Thursday. A second study indicated that people who initially received Pfizer’s COVID-19 vaccine and got a Johnson & Johnson (J&J) booster saw a 41-fold increase in neutralizing antibody responses and a jump in T-cells within weeks. The first study analyzed over 69,000 vaccinated health care workers, pegged effectiveness against hospitalization at 63 percent zero to 13 days after the boost. That figure climbed to 85 percent one to two months post-boost. The study did not include an assessment of effectiveness past that time frame. “We provide the first evidence of the effectiveness of a homologous Ad26.COV.2 vaccine boost given 6-9 months after the initial single vaccination series during a period of omicron variant circulation,” authors wrote in the preprint study. They received …