The average person doesn’t need a COVID-19 booster yet, an international group of scientists — including two top U.S. regulators — wrote Monday in a scientific journal. The experts reviewed studies of the vaccines’ performance and concluded the shots are working well despite the extra-contagious delta variant, especially against severe disease. “Even in populations with fairly high vaccination rates, the unvaccinated are still the major drivers of transmission” at this stage of the pandemic, they concluded.