Evidence emerges people without symptoms can spread coronavirus

The European Union’s disease prevention agency is set to tighten its advice on coronavirus as evidence emerges that people showing no symptoms can spread the virus.

Until Monday the European Centre for Disease Prevention and Control (ECDC) had advised that “people who are infected but who do not show symptoms cannot transmit the virus”, a belief that has influenced policy and quarantine decisions in several EU countries as cases balloon.

This was in conflict with advice from the World Health Organization and the US Centers for Disease Control and Prevention. The WHO states that, while rare, "there are people who can shed Covid-19 virus 24-48 hours prior to symptom onset".

Chinese researchers reported a case of asymptomatic transmission on February 21st, and German doctors wrote to the New England Journal of Medicine on March 5th to warn they had identified a case of transmission by a person without symptoms near Munich.

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Asked by The Irish Times why it advised that the virus could not be transmitted without symptoms, the ECDC responded that it “will be updating the information on our webpage within the coming days”.

A spokeswoman confirmed this was an update of advice on asymptomatic transmission, declining to give further details.

It comes as cases of the disease have boomed around Europe and Italy announced a national lockdown to try to prevent the virus from spreading, encouraging all citizens to stay at home if they can and avoid social contacts.

Citizens who must venture out are advised to keep a distance of one metre from other people.

The death toll in Italy spiked by 97 to 463 on Monday, as overall cases in the hardest-hit EU country topped 9,000.

In France, culture minister Franck Riester tested positive for the virus, and gatherings of more than 1,000 people have been banned as cases rose to 1,412 with 25 deaths. The chief executive of France's busiest airports Paris Charles de Gaulle and Orly, Augustin de Romanet, also tested positive.

In Spain, schools and universities in the Madrid region and schools in the capital of the Basque region Vitoria are to close for two weeks as a precaution as the infection spread further there. Official figures show 28 people have died in Spain from the virus, and there are a total of 1,204 cases.

Israel has announced it will require anyone arriving from overseas to self-quarantine for 14 days as a precaution, as the number of cases reached 43 there. Non-Israelis seeking to enter the country will have to prove they have the means to self-quarantine, and the measure could affect 300,000 citizens in a country of about nine million according to local media.

‘Example’

Portuguese president Marcelo Rebelo de Sousa announced from his balcony that he would observe voluntary quarantine for two weeks despite testing negative for coronavirus, as an "example" to Portuguese people.

“I’m going to keep working from home,” he yelled to media below, as cases reached 35 in the country. He added later in a telephone interview: “I had commitments involving hundreds, thousands of people in the coming weeks. It’s not worth the risk.”