The need is not crystal clear. Studies show the vaccines are still offering strong protection against serious illness for all ages. And many experts want to focus attention on getting shots to the unvaccinated, the group most in danger of infection, hospitalization and death.
On the other hand, there is a slight drop in the vaccine's effectiveness among the oldest adults. And immunity against milder infection appears to wane months after people's initial shots. Protecting health care workers from even mild illness may help some hospitals now struggling to care for unvaccinated COVID-19 patients.