LONDON – Six weeks on from the initial alert, “the window of opportunity” to control the COVID-19 epidemic is “narrowing,” according to the latest assessment from World Health Organization (WHO) Director General Tedros Adhanom Ghebreyesus.

“We need to act quickly, before the window closes completely,” Ghebreyesus said in an update from WHO headquarters in Geneva on Feb. 21.

In support of this, the WHO-led expert mission to China is due to travel to the epicenter of the outbreak in the city of Wuhan on Saturday Feb. 21. Elsewhere, WHO has stepped up its response by appointing six special envoys on COVID-19 to provide strategic advice and high level political advocacy in different parts of the world.

Although the number of cases outside China is low, the situation is now “very worrisome,” Ghebreyesus said. In particular, he cited 18 cases and four deaths from the novel coronavirus that had been reported from Iran in two days. It appears those are not connected to travel to China or contact with people who have been in China.

In addition, confirmed cases have been reported from Canada and Lebanon in individuals who had traveled from Iran. Two more suspected cases are being investigated in Lebanon.

With Iran under economic sanctions and Lebanon in a parlous financial situation, Ghebreyesus expressed concern about the potential for COVID-19 to spread in countries with weaker health care systems. Iran and Lebanon have the laboratory capacity to detect the virus and WHO has been in touch to offer assistance, Ghebreyesus said.

As of 6 am CET on Feb. 21, 1,152 cases of COVID-19 infection outside China had been reported by 62 countries. There have been eight deaths. “The total number is relatively small, but I am concerned about the number of cases with no epidemiological links,” said Ghebreyesus.

A further source of concern is the rapid increase in confirmed cases in South Korea, where the number of infections more than doubled from Feb. 19 to Feb. 21, reaching 204. Four confirmed cases are in people with no history of being in China, or having contact with anyone who had traveled there.

Daegu and Cheongdo, cities in southern South Korea, have been declared “special care zones” and military bases across the country are under quarantine, after three soldiers tested positive.

Ghebreyesus said WHO is working with the South Korean government to fully understand the transmission dynamics.

The cluster of cases in South Korea is the second largest outside China after those on the Diamond Princess, the cruise ship quarantined in Yokohama, Japan, on Feb. 5. Of 3,700 passengers, more than 620 have tested positive for COVID-19. Two Australians, who tested negative when they were released from the ship after 14 days quarantine, were confirmed to have the virus on being repatriated on Feb. 21.

Cases fall in China, as reporting standard changes again

In China, there are now 75,567 confirmed cases and 2,239 deaths. In the 24 hours to Feb. 21, 892 new cases were confirmed, and there were 118 deaths.

That is a significant decline in new cases, but as Ghebreyesus noted, the fall is partly due to another change in the way China reports numbers.

“As you know, last week China started reporting clinically diagnosed cases, in addition to laboratory-confirmed cases. They have now switched back to reporting only suspected and lab-confirmed cases,” he said.

As a result, some cases that had been clinically confirmed have been subtracted from the total because the laboratory test was negative.

That may indicate that after being overwhelmed by the volume of infections, the health system in Wuhan is getting on top of problem and now has the capacity to test all suspect cases.

But although the number of cases in Hubei province, where Wuhan is situated, continues declining, Ghebreyesus said he is concerned about an increase in cases in Shandong province. “We are seeking more information about that,” he said.

Gaps in knowledge of epidemiology frustrate control measures

The latest published research on what is known so far about the epidemiology of COVID-19 highlights how gaps in knowledge are undermining control efforts.

A paper by clinicians in China, published in JAMA on Feb. 21, describes the possible transmission of the virus from a resident of Wuhan who was asymptomatic, to five family members in the city of Anyang, in the neighboring province of Henan.

The five fell ill between Jan. 17 and Jan. 26, after initial contact between Jan. 10 and Jan. 13 with the 20-year-old woman who had traveled from Wuhan. The woman herself remained fit, with a normal chest CT scan, though after a negative result on Jan. 26, she did test positive for COVID-19 on Jan. 28.

This is the first report of transmission from an asymptomatic carrier. “If the findings in this report of presumed transmission by an asymptomatic carrier are replicated, prevention of COVID-19 infection could prove challenging,” the researchers conclude.

Also on Feb. 21, researchers at the WHO Collaborating Center for Infectious Disease Modeling at Imperial College, London, published their latest analysis, looking at COVID-19 cases exported from mainland China. They compared country-specific rates of detected and confirmed cases per flight volume from Wuhan City airport, to estimate the relative sensitivity of surveillance in different countries.

Although travel restrictions have reduced the number of travelers to and from China, the researchers estimate about two-thirds of COVID-19 cases exported from China have remained undetected worldwide. As a result, there may be multiple chains of as-yet-undetected human-to-human transmission outside China.

“Undoubtedly, the exported cases vary in the severity of their clinical symptoms, making some cases more difficult to detect than others. However, some countries have detected significantly fewer than would have been expected,” based on the number of passengers coming from Wuhan city airport, the researchers conclude.

“We should not be surprised this report suggests that this virus is more widespread than official figures suggest,” said Jonathan Ball, professor of molecular virology at Nottingham University, commenting on the analysis. “With each new finding of how this virus is behaving – large proportions of people with mild or no symptoms, frequent detection of the virus in the nose and throat irrespective of disease severity – we should start to accept that this outbreak will be incredibly difficult to control using standard public health measures, such as isolation of cases and contact tracing.

“I don’t think too many people would argue that we are likely to see continued spread around the world and the eventual emergence of what will be the fifth commonly circulating human coronavirus infection,” Ball said.

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