Several countries that have lifted coronavirus restrictions and reopened businesses, including China, have seen jumps in coronavirus cases, underscoring the "challenges that may lie ahead," the World Health Organization warned Monday.
"In the Republic of Korea, bars and clubs were shut as a confirmed case led to many contacts being traced," WHO Director-General Tedros Adhanom Ghebreyesus said during a press conference at the agency's headquarters in Geneva. "In Wuhan, China, the first cluster of cases since the lockdown lifted was identified. Germany has also reported an increase in cases since the easing of restrictions."
Tedros urged caution as more countries seek to ease such restrictions and jump-start the economy. He added that South Korea, China and Germany have all rolled out surveillance infrastructure such as broad testing and tracing to alert authorities in case the virus does reassert itself.
Before any country begins to lift restrictions, it should have the epidemic under control, ensure that its health systems are able to cope with a potential resurgence and have necessary testing, tracing and isolating infrastructure in place, Tedros said.
"Countries put these stringent measures in place, sometimes called lockdowns, in response to intense transmission," he said. "Many have used the time to ramp up their ability to test, trace, isolate and care for patients, which is the best way to track the virus, slow the spread, and take pressure off the health systems."
Serological, or antibody, studies show that a relatively low portion of the population has antibodies to Covid-19, which means many are still susceptible to the virus, Tedros said. He added that the WHO understands the economic costs of shutdown measures and encourages countries to take "a slow, steady" approach in lifting restrictions.
The lifting of the shutdown measures represents "some hope," said Dr. Mike Ryan, executive director of WHO's emergencies program. He added that "extreme vigilance" is needed as well as the necessary public health infrastructure, which some countries have yet to implement.
"Many countries have made very systematic investments in building up their public health capacities during those lockdowns. Others have not," he said. "And we need every country to put in place the necessary public health measures, public health surveillance, in order to be able to at least have a chance of avoiding larger second waves later."
The apparent resurgence in cases abroad comes as dozens of states across the U.S. begin to reopen nonessential businesses and lift restrictions. Some states such as Texas reopened businesses even as their new daily confirmed cases continued to rise, according to epidemiologists.
The U.S. has performed just under 9 million coronavirus tests in total as of Sunday and more than 277,000 on Sunday, according to data compiled by the Covid Tracking Project.
On Saturday, the U.S. Food and Drug Administration issued the first emergency use authorization for a new category of tests to help rapidly detect coronavirus antigens.
Antigen tests can provide results in minutes and can be rolled out much quicker than other types because the equipment needed to process them is already used for flu and strep testing. However, the antigen tests' negative results aren't as accurate as those of more standard PCR diagnostic tests.
Due to the nature of the virus and potential testing limitations in some states, public health officials may not know of a resurgence in cases for days or even weeks after someone became infected, developed symptoms, got tested and received the results.