Johnson & Johnson (NYSE:JNJ) has announced that a booster of its viral-vector COVID-19 vaccine led to considerable increases in coronavirus spike-binding antibodies, according to interim data from two Phase 1/2 trials known as VAC31518COV1001 and VAC31518COV2001. In particular, the boosters led to a nine-fold increase in antibodies relative to levels 28 days after administering the prime…