"The virus is spreading more actively than ever before," PAHO Director Carissa Etienne told a briefing.
The Caribbean has had the steepest increase in infections since the start of the two-year-old pandemic, the regional agency said. In North America, the United States and Canada are experiencing a surge of COVID-19 hospitalisations.
Given a shortage of testing, PAHO recommended that countries prioritize rapid antigen tests for people with COVID-19 symptoms and who are at risk of spreading the virus.
Even though more than 60% of people in Latin America and the Caribbean have been fully vaccinated against COVID-19, omicron is spreading rapidly in all regions, said PAHO Incident Manager Sylvain Aldighieri.
The variant's advance in coming weeks and months will depend on public health measures to contain it, including use of masks and social distancing and above all vaccinations, to reduce the severity of COVID-19 cases and hospitalisations, he said.
Brazil reported a record 137,103 cases of the coronavirus in 24 hours as omicron spread in Latin America's largest country, the Health Ministry said on Tuesday, as new infections soared above the previous daily record of 115,228 in June last year.
Brazil has the world's third highest death toll from COVID-19 after the United States and Russia, according to a Reuters tally.