Epidemics were afraid of what has now occurred: that the new corona virus will spread locally beyond individual cases in many parts of the world outside of China. "It seems to me that this virus has really escaped from China and is now quite widespread," said British epidemiologist Christopher Dye. Experts are not really surprised by this new phase of the outbreak that is now emerging: in Asia, the Middle East and, with Italy, also in Europe.

In Italy, more than 200 people have been infected with the new Sars-Cov-2 coronavirus, and five have died. The authorities' reaction is drastic: schools are being closed in the north of the country, the Venice Carnival has been canceled and entire communities have been quarantined. "These extraordinary measures in northern Italy are crucial to contain the outbreak," said Andrea Ammon, head of the European Disease Control Agency, Andrea Ammon on Sunday. "They may need to be taken to other churches in the coming days." The goal: to prevent the virus from spreading too quickly - to Europe and the world.

When this happens when a new pathogen spreads worldwide, experts call it a pandemic. The World Health Organization has so far avoided the word when it communicates about the novel coronavirus Sars-CoV-2. But many experts are now using the "P-word" when talking about the pathogen and the lung disease Covid-19 caused by it.

Since China reported an accumulation of unusual pneumonia at the end of December, the virus from the coronavirus family, which is related to the Sars pathogen, has spread rapidly. There are now around 80,000 confirmed cases, the majority of which are in China. And scientists assume that the number of unreported cases is high - since many infected people only experience mild cold symptoms.

The WHO's strategy to stop the outbreak was crystal clear - and General Director Tedros Adhanom Ghebreyesus explains it over and over again: fight the virus with all its might at its source in China and at the same time prevent it from gaining a foothold elsewhere. The world has a chance to stop it, he does not tire of stressing. Most recently, he said this by video link to the health ministers of Africa gathered in Addis Ababa. There is still a chance to contain the outbreak, even if the window for it is slowly closing.

The strategy was correct and important. "If this virus behaved like Sars, it would probably have worked," said epidemiologist Alessandro Vespignanivon of Northeastern University in Boston. But Sars-CoV-2 behaves differently, we now know that. The world has saved valuable time due to strict quarantine measures in China and travel restrictions. But the past week has shown that the pathogen can probably not be prevented from spreading worldwide.

On the one hand, there is the virus itself: it is more contagious than the flu and causes only mild symptoms in many people that are not easy to recognize. The way it has spread in hospitals, churches and on cruise ships is another warning sign. There, the virus not only spread quickly, but also widely.

And then there are the new cases outside of China.

Hundreds of people have been infected in Japan and South Korea. And it is not clear in every case how they got infected. This indicates that the virus was able to spread silently there as well. Even Singapore, which is widely regarded as the gold standard when it comes to tracking down cases of illness, finding contact persons and thus containing an infection, has to do with nine cases where it is not clear where they were infected.

In Iran, where there wasn't officially a single Covid 19 case until Wednesday, more than 60 infections have now been registered and twelve deaths have been officially confirmed. According to media reports, 50 people may already have died of Covid-19 in the city of Qom in February. Either way, the known cases should only be the tip of the iceberg; after all, researchers are currently assuming that only around one in 100 infections leads to death. The fact that the pathogen has already been detected in travelers to Iran in other countries also suggests that there are many more cases. How big the iceberg really is, that will show in the next days and weeks.