The World Health Organization (WHO) urged countries on Monday to press on with efforts to contain the novel coronavirus, noting the pandemic was worsening globally and had not peaked in central America.
More than 136,000 cases were reported worldwide on Sunday, "the most in a single day so far", WHO Director General Tedros Adhanom Ghebreyesus said.
"More than six months into the pandemic, this is not the time for any country to take its foot off the pedal," he told an online briefing.
In response to a question on China, WHO's top emergencies expert, Dr Mike Ryan, said retrospective studies of how the outbreak has been addressed could wait, adding: "We need to focus now on what we are doing today to prevent second peaks."
Ryan also said infections in central American countries including Guatemala were still on the rise, and that they were "complex" epidemics.
"I think this is a time of great concern," he said, calling for strong government leadership and international support for the region.
Brazil is now one of the hotspots of the pandemic, with the second highest number of confirmed cases, behind only the United States, and a death toll that last week surpassed Italy's.
After removing cumulative numbers for coronavirus deaths in Brazil from a national website, the Health Ministry sowed further confusion and controversy by releasing two contradictory sets of figures for the latest tally of infection cases and fatalities.
Ryan said Brazil's data had been "extremely detailed" so far but stressed it was important for Brazilians to understand where the virus is and how to manage risk, and that the WHO hoped communication would be "consistent and transparent".
Maria van Kerkhove, a WHO epidemiologist, said that a "comprehensive approach" was essential in South America.
More than 7 million people have been reported infected with the coronavirus globally and over 400,000 have died.
"This is far from over," van Kerkhove said.
At least half of Singapore's newly discovered coronavirus cases show no symptoms, the co-head of the government's virus taskforce told Reuters on Monday, reinforcing the city-state's decision to ease lockdown restrictions very gradually.
Van Kerkhove said that many countries doing contact tracing had identified asymptomatic cases but were not finding that they caused further spread of the virus, adding: "It is very rare".
Ryan, asked about technical cooperation with the United States, after President Donald Trump's announcement 10 days ago that it was 'terminating' its relationship with the WHO, said the WHO relies heavily on experts from the Centers for Disease Control and National Institute of Health.
"We will continue to do that until we are otherwise instructed or informed," he added.