Booster shots are keeping the Omicron variant from landing millions of Americans in hospitals, emergency rooms and urgent care clinics across the country, three new government studies show. [In one study] a third dose of either the Pfizer or Moderna vaccines was 90% effective at preventing hospitalization, and at least 82% effective in preventing a trip to the emergency room or urgent care. … [A second study] found that booster shots also protected Americans, particularly those over 50, from COVID-related deaths. … [A third report] found that among Americans tested for COVID-19 in December 2021, three doses of an mRNA vaccine offered greater protection against cases of symptomatic COVID-19 infection than being fully vaccinated (with two doses) or unvaccinated did.