Johnson & Johnson announced this morning that its COVID-19 booster shot is 94% effective when administered two months after the first dose.

They say it also increases antibody levels four to six times higher than one shot alone.

The company also said that those who got the booster tolerated it well - and side effects were generally consistent with those seen after the initial dose.

When a booster of the Johnson & Johnson COVID-19 vaccine was given six months after the single shot, antibody levels increased nine-fold one week after the booster and continued to climb to 12-fold higher four weeks after the booster.