In Rio de Janeiro, where the virus has already killed tens of thousands, upturned the economy and sent rates of homelessness soaring, moments that recall the darkest days of the pandemic are once more appearing in the news.

Sick people, unable to get help in the medical system, are again being found dead at home. Lines stretching into the hundreds are forming for intensive care beds. Hospital officials are warning of supply shortages and an imminent collapse in medical services.

Even the vaunted private heath-care system reached 98 percent capacity in its intensive care units this past week, officials said. In states across the country, the situation wasn’t much better.