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Houston, Mar 15: Researchers, studying the novel coronavirus, have found that the time between cases in a chain of transmission is less than a week, and over 10 per cent of patients are infected by someone who has the virus, but does not show symptoms yet, a finding that may help public health officials contain the pandemic.

The study, published in the journal Emerging Infectious Diseases, estimated what's called the serial interval of the coronavirus by measuring the time it takes for symptoms to appear in two people with the virus -- the person who infects another, and the infected second person.

According to the researchers, including those from the University of Texas at Austin, the average serial interval for the novel coronavirus in China was approximately four days.

They said the speed of an epidemic depends on two things -- how many people each case infects, and how long it takes cases to spread.

The first quantity, the scientists said, is called the reproduction number, and the second is the serial interval.

Due to the short serial interval of the disease caused by the coronavirus -- COVID-19 -- they said, emerging outbreaks will grow quickly, and could be difficult to stop.

“Ebola, with a serial interval of several weeks, is much easier to contain than influenza, with a serial interval of only a few days,” said Lauren Ancel Meyers, study co-author from UT Austin.

Meyers explained that public health responders to Ebola outbreaks have much more time to identify and isolate cases before they infect others.

“The data suggest that this coronavirus may spread like the flu. That means we need to move quickly and aggressively to curb the emerging threat,” Meyers added.

In the study, the scientists examined more than 450 infection case reports from 93 cities in China, and found the strongest evidence yet that people without symptoms must be transmitting the virus -- known as pre-symptomatic transmission.

More than one in ten infections were from people who had the virus but did not yet feel sick, the scientists said.

While researchers across the globe had some uncertainty until now about asymptomatic transmission with the coronavirus, the new evidence could provide guidance to public health officials on how to contain the spread of the disease.

“This provides evidence that extensive control measures including isolation, quarantine, school closures, travel restrictions and cancellation of mass gatherings may be warranted,” Meyers said.

The researchers cautioned that asymptomatic transmission makes containment more difficult.

With hundreds of new cases emerging around the world every day, the scientists said, the data may offer a different picture over time.

They said infection case reports are based on people's memories of where they went and whom they had contact with, and if health officials move quickly to isolate patients, that may also skew the data.

“Our findings are corroborated by instances of silent transmission and rising case counts in hundreds of cities worldwide. This tells us that COVID-19 outbreaks can be elusive and require extreme measures,” Meyers said.

Beijing, May 25: China has reported 51 new coronavirus cases including 40 asymptomatic infections, majority of them in the contagion's first epicentre Wuhan, where over six million tests have been conducted in the last 10 days, health officials said on Monday.

The country's National Health Commission (NHC) said that 11 new imported cases were reported on Sunday.

While no new domestically-transmitted COVID-19 cases were reported in China on Sunday, 11 imported cases including 10 in the Inner Mongolia Autonomous Region and one in Sichuan province were reported, the NHC said in its daily report.

Out of the 40 new asymptomatic cases, 38 were reported in Wuhan, which is currently undergoing mass testing of its over 11.2 million people after a spike in the asymptomatic cases.

Currently, 396 people with asymptomatic symptoms are under medical observation in China, including 326 in Wuhan, according to the health authority.

Asymptomatic cases refer to the patients who have tested COVID-19 positive but develop no symptoms such as fever, cough or sore throat. However, they pose a risk of spreading the disease to others.

Wuhan, which earlier had over 50,000 cases between January and March, started a campaign on May 14 to expand the nucleic acid testing in order to better know the number of asymptomatic cases or people who show no clear symptoms despite carrying the virus.

According to the latest figures released by the Wuhan municipal health commission, the city conducted more than 6 million nucleic acid tests between May 14 and 23.

On Saturday, the city carried out nearly 1.15 million tests, state-run Xinhua news agency reported on Monday.

Nucleic acid testing is a molecular technique for screening blood donations to reduce the risk of transfusion transmitted infections.

As of Sunday, a total of 82,985 confirmed COVID-19 cases have been reported in China with 4,634 fatalities, the NHC added.

Tehran, Feb 28: The coronavirus epidemic in Iran has cost 26 lives, the health ministry announced Thursday, with a vice president becoming the latest top official to be infected as the spread appeared to accelerate.

Health ministry spokesman Kianoush Jahanpour told a news conference that the tally of infections had risen to 245 with 106 more cases confirmed -- the highest number for a single day since Iran announced its first infections on February 19.

The Islamic republic has the highest death toll from the virus outside China, where COVID-19 first emerged.

Among the latest coronavirus sufferers is one of Iran's seven vice presidents, Massoumeh Ebtekar, who oversees women's affairs.

Ebtekar, a former spokeswoman for students who took 52 Americans hostage at the US embassy in Tehran in 1979, is being treated at home and members of her team have been tested, state news agency IRNA reported.

Mojtaba Zolnour, head of parliament's national security and foreign affairs committee, also contracted the virus, appearing in a video posted by Fars news agency saying he was in self-quarantine.

The cleric is a deputy for the Shiite holy city of Qom in central Iran where the country's first cases were detected.

According to media reports, among the deceased in Qom on Thursday was theologian Hadi Khroroshahi, who in 1981 was named Iran's first ambassador to the Vatican.

The announcement by Zolnour comes two days after another top official, deputy health minister Iraj Harirchi, head of the government's coronavirus task force, said he too had contracted the virus.

On Wednesday, Iranian authorities announced domestic travel restrictions for people with confirmed or suspected infections.

They also placed curbs on access to major Shiite pilgrimage sites, including the Imam Reza shrine in second city Mashhad and the Fatima Masumeh shrine in Qom.

Visitors to the shrines will be allowed to visit on condition they are provided "with hand-washing liquids, proper (health) information, masks", Health Minister Saeed Namaki said.

They must "not gather together in groups but just pray and leave", he said.

In a rare move, authorities announced the cancellation of the main Friday weekly prayers in Tehran, Qom and Mashhad as well as in the capitals of 22 of Iran's 31 provinces and other infected areas.

"All of these decisions are temporary and if the situation changes, we might intensify or ease them," Namaki said.