Latin America risks other outbreaks as Covid interferes with prevention and treatment.

The coronavirus pandemic is opening the way for other preventable diseases to surge across Latin America and the Caribbean, interfering with routine inoculations and medical treatment in one of the world’s hardest-hit regions, World Health Organization officials warned on Wednesday.

There has been a sharp decline in measles vaccinations throughout the region, and a recent survey found that the pandemic has slowed efforts to diagnose and treat viral hepatitis B and C infections throughout Latin America and the Caribbean.

“More than 300,000 children, mostly in Brazil and Mexico, missed out on their routine immunizations last year, leaving them vulnerable to deadly yet preventable infections,” said Dr. Carissa Etienne, the director of the Pan American Health Organization, a part of the W.H.O.

“If we do not reverse these trends we risk an avalanche of worsening health issues in the Americas,” she added. “Soon, Covid-19 will not be the only health crisis demanding countries’ attention.”

Though overall caseloads have declined in the region since the spring, Covid-19 continues to take a devastating toll, and several Latin American nations, including Argentina, Colombia, Cuba, Ecuador and Paraguay are “among the countries reporting the world’s highest weekly death rates,” Dr. Etienne said at a weekly briefing. She warned that “too many places have relaxed the public health and safety measures that have proven so effective against this virus.”

Officials voiced particular concern about Cuba, which is reporting its highest rates of new cases and deaths since the pandemic began. Hot spots have also been detected in parts of Argentina, Colombia and Mexico, and new cases have risen sharply in the United States.

Though vaccines have been plentiful in the United States, Canada, Chile, Uruguay and a few other countries in the Americas, they have been scarce elsewhere. Only one-sixth of the population of Latin America and the Caribbean has been fully vaccinated.

One of the most extreme examples is Haiti, which was only recently able to begin its vaccination campaign after a donation of shots from the United States.