NEW YORK (AP) — Three studies released Friday offered more evidence that COVID-19 vaccines are standing up to the omicron variant, at least among people who received booster shots.

They are the first large U.S. studies to look at vaccine protection against omicron, health officials said.

The papers echo previous research — including studies in Germany, South Africa and the U.K. — indicating available vaccines are less effective against omicron than earlier versions of the coronavirus, but also that boosters doses rev up virus-fighting antibodies to increase the chance of avoiding symptomatic infection.

The first study looked at hospitalizations and emergency room and urgent care center visits in 10 states, from August to this month.

It found vaccine effectiveness was best after three doses of the Pfizer or Moderna vaccines in preventing COVID-19-associated emergency department and urgent care visits. Protection dropped from 94% during the delta wave to 82% during the omicron wave. Protection from just two doses was lower, especially if six months had passed since the second dose.

Officials have stressed the goal of preventing not just infection but severe disease. On that count, some good news: A third dose was at least 90% effective at preventing hospitalizations for COVID-19, both during the delta and omicron periods, the study also found.