COVID-19 spreads even before people show symptoms, study says

Melbourne, Apr 10: Scientists have identified six drug candidates from more than 10,000 compounds that may help treat COVID-19.

The research, published in the journal Nature, tested the efficacy of approved drugs, drug candidates in clinical trials and other compounds.

"Currently there are no targeted therapeutics or effective treatment options for COVID-19," said Professor Luke Guddat from the University of Queensland in Australia.

"In order to rapidly discover lead compounds for clinical use, we initiated a programme of high-throughput drug screening, both in laboratories and also using the latest computer software to predict how different drugs bind to the virus," Guddat said.

The project targeted the main COVID-19 virus enzyme, known as the main protease or Mpro, which plays a pivotal role in mediating viral replication, the researchers said.

This makes it an attractive drug target for this virus, and as people don't naturally have this enzyme, compounds that target it are likely to have low toxicity, they said.

"We add the drugs directly to the enzyme or to cell cultures growing the virus and assess how much of each compound is required to stop the enzyme from working or to kill the virus. If the amount is small, then we have a promising compound for further studies," said Guddat.

After assaying thousands of drugs, researchers found of the six that appear to be effective in inhibiting the enzyme, one is of particular interest.

"We're particularly looking at several leads that have been subjected to clinical trials including for the prevention and treatment of various disorders such as cardiovascular diseases, arthritis, stroke, atherosclerosis and cancer," Guddat said.

Researchers said compounds that are already along the pipeline to drug discovery are preferred, as they can be further tested as antivirals at an accelerated rate compared to new drug leads that would have to go through this process from scratch.

"With continued and up-scaled efforts we are optimistic that new candidates can enter the COVID-19 drug discovery pipeline in the near future," Guddat said.

London/Milan, Jun 2: World Health Organization experts and a range of other scientists said on Monday there was no evidence to support an assertion by a high profile Italian doctor that the coronavirus causing the COVID-19 pandemic has been losing potency.

Professor Alberto Zangrillo, head of intensive care at Italy's San Raffaele Hospital in Lombardy, which bore the brunt of Italy's COVID-19 epidemic, on Sunday told state television that the new coronavirus "clinically no longer exists".

But WHO epidemiologist Maria Van Kerkhove, as well as several other experts on viruses and infectious diseases, said Zangrillo's comments were not supported by scientific evidence.

There is no data to show the new coronavirus is changing significantly, either in its form of transmission or in the severity of the disease it causes, they said.

"In terms of transmissibility, that has not changed, in terms of severity, that has not changed," Van Kerkhove told reporters.

It is not unusual for viruses to mutate and adapt as they spread, and the debate on Monday highlights how scientists are monitoring and tracking the new virus. The COVID-19 pandemic has so far killed more than 370,000 people and infected more than 6 million.

Martin Hibberd, a professor of emerging infectious disease at the London School of Hygiene & Tropical Medicine, said major studies looking at genetic changes in the SARS-CoV-2 virus that causes COVID-19 did not support the idea that it was becoming less potent, or weakening in any way.

"With data from more than 35,000 whole virus genomes, there is currently no evidence that there is any significant difference relating to severity," he said in an emailed comment.

Zangrillo, well known in Italy as the personal doctor of former Prime Minister Silvio Berlusconi, said his comments were backed up by a study conducted by a fellow scientist, Massimo Clementi, which Zangrillo said would be published next week.

Zangrillo told Reuters: "We have never said that the virus has changed, we said that the interaction between the virus and the host has definitely changed."

He said this could be due either to different characteristics of the virus, which he said they had not yet identified, or different characteristics in those infected.

The study by Clementi, who is director of the microbiology and virology laboratory of San Raffaele, compared virus samples from COVID-19 patients at the Milan-based hospital in March with samples from patients with the disease in May.

"The result was unambiguous: an extremely significant difference between the viral load of patients admitted in March compared to" those admitted last month, Zangrillo said.

Oscar MacLean, an expert at the University of Glasgow's Centre for Virus Research, said suggestions that the virus was weakening were "not supported by anything in the scientific literature and also seem fairly implausible on genetic grounds."

As the deadly coronavirus has spread worldwide, it has carried with it xenophobia -- and Asian communities around the world are finding themselves subject to suspicion and fear.

When a patient on Australia's Gold Coast refused to shake the hand of her surgeon Rhea Liang, citing the virus that has killed hundreds, the medic's first response was shock.

But after tweeting about the incident and receiving a flood of responses, the respected doctor learned her experience was all too common.

There has been a spike in reports of anti-Chinese rhetoric directed at people of Asian origin, regardless of whether they have ever visited the centre of the epidemic or been in contact with the virus.

Chinese tourists have reportedly been spat at in the Italian city of Venice, a family in Turin was accused of carrying the disease, and mothers in Milan have used social media to call for children to be kept away from Chinese classmates.

In Canada, a white man was filmed telling a Chinese-Canadian woman "you dropped your coronavirus" in the parking lot of a local mall.

In Malaysia, a petition to "bar Chinese people from entering our beloved country" received almost 500,000 signatures in one week.

The incidents are part of what the Australasian College for Emergency Medicine has described as "misinformation" which it says is fuelling "racial profiling" where "deeply distressing assumptions are being made about 'Chinese' or 'Asian-looking' people." Disease has long been accompanied by suspicions of foreigners -- from Irish immigrants being targeted in the Typhoid Mary panic of 1900s America to Nepali peacekeepers being accused of bringing cholera to earthquake-struck Haiti in the last decade.

"It's a common phenomenon," said Rob Grenfell, director of health and biosecurity for Australia's science and research agency CSIRO.

"With outbreaks and epidemics along human history, we've always tried to vilify certain subsets of the population," he said, comparing the behaviour to 1300s plague-ridden medieval Europe, where foreigners and religious groups were often blamed.

"Sure it emerged in China," he said of the coronavirus, "but that's no reason to actually vilify Chinese people." In a commentary for the British Medical Journal, doctor Abraar Karan warned this behaviour could discourage people with symptoms from coming forward.

Claire Hooker, a health lecturer at the University of Sydney, said the responses from governments may have compounded prejudice.

The World Health Organisation has warned against "measures that unnecessarily interfere with international travel and trade", but this has not stopped scores of countries from introducing travel bans.

The tiny Pacific nation of Micronesia has banned its citizens from visiting mainland China altogether.

"Travel bans respond largely to people's fears," said Hooker, and while sometimes warranted, they often "have the effect of cementing an association between Chinese people and scary viruses".

Abbey Shi, a Shanghai-born student in Sydney, said the attitude shown by some of her peers has "become almost an attack on students who are Chinese".

While Australia's conservative government has banished its citizens returning from Wuhan -- the central Chinese city at the epicentre of the virus -- to a remote island for quarantine, thousands of students still stuck in China risk their studies being torpedoed.

"Right now it looks like they have to miss the semester's start and potentially the whole year, because of the way the courses are set up," Shi said.

According to Hooker, studies in Toronto on the impact of Severe Acute Respiratory Syndrome, or SARS -- another global coronavirus outbreak in 2002 -- showed the impact of xenophobic sentiment often lasted much longer than the public health scare.

"While there may be a cessation of direct forms of racism as news about the disease dies down, it takes quite a bit of time for economic recovery and people continue to feel unsafe," she said.

People may not rush back to Chinese businesses or restaurants, and may even heed some of the more outlandish viral social media disinformation -- such as one popular post imploring people to avoid eating noodles for their own safety.

"In one sense you might think the effects lasted from the last coronavirus to this one because the representation as China being a place where diseases come from has been persistent," Hooker said.