Covid-19 escalates.

WHO calls for more testing as countries worldwide bring in strict measures to slow new coronavirus's spread, reports Adam Vaughan.

THE total number of coronavirus cases and deaths outside China has now overtaken those within the country. Around the world, countries have closed borders and ramped up social distancing measures.

When New Scientist went to press, there had been more than 180,000 confirmed cases and more than 7000 deaths globally. China has still had the highest number of cases, followed by Italy and Iran. Spain is now fourth, having overtaken South Korea.

Many countries are imposing border restrictions to reduce the spread of the virus, including Canada, Costa Rica and Tunisia. The European Union closed its external borders on Tuesday.

The World Health Organization's director general Tedros Adhanom Ghebreyesus said on Monday that there has been a “rapid escalation” of cases in the past week. He said that while governments had increased efforts to slow the outbreak, they weren't doing enough, and called for continued testing.

“You cannot fight a fire blindfolded. And we cannot stop this pandemic if we don't know who is infected. We have a simple message for all countries: test, test, test. Test every suspected case,” he told journalists at a briefing.

His comments came as the UK stepped up its response, with prime minister Boris Johnson announcing a “national fightback” against the virus. Guidance included avoiding unnecessary social contact, ending non-essential travel and other social distancing steps. However, the measures are voluntary and stop short of many of the country's European neighbours, several of which have closed schools and instituted mandatory lockdowns.

It is thought that a new modelling study by a team led by Neil Ferguson at Imperial College London may have influenced the UK's new measures. The team's analysis, which the UK government told New Scientist had been discussed at meetings informing the new policies, says previous estimates of predicted demand for intensive care units in hospitals had been doubled because of data coming in from Italy and the UK.

Intensive care is still likely to be overwhelmed even with the new steps, with demand likely to be eight times higher than availability even in the most optimistic scenario, the team warned.

21 Number of new, confirmed cases in China on 16 March

France is taking a more extreme approach, and from Tuesday the whole country's population must “stay at home” for anything other than food shopping, medical supplies or exercise. Flouting the rules risk fines of up to €135 (£121).

In the US on Monday, the White House issued guidelines as part of its “15 days to slow the virus” campaign. Chief among them is a ban on mass gatherings, with people told to avoid gathering in groups of more than 10, and to avoid bars, restaurants and unnecessary travel.

Australia, which has had relatively few cases so far, told Australians to come home from abroad and is weighing up stronger measures.

New cases in China, where the virus originated, have stayed low in recent days. The country confirmed 21 cases on Monday, 20 of which were people arriving from abroad.

South Korea, which was also hit early by the virus but has tested at a greater rate than any other country, had its third day running with fewer new cases, at 84 on Monday.

The latest coronavirus news online Stay up to date with the science of covid-19 newscientist.com/article-type/coronavirus