According to researchers, a larger outbreak of the coronavirus can be avoided with a combination of measures for the time being. At least in Singapore, it says in the specialist magazine “The Lancet Infectious Diseases”.
Comprehensive school closings, work in the home office for half the population and strict quarantine for sick people and their families: According to a simulation study from Singapore, these three measures together over the period of two weeks could suppress the new corona virus.
For the Southeast Asian city-state, this means in concrete terms: Instead of – as in the worst of the scenarios modeled – 1.2 million people, almost a third of the population, an assumed high infection rate could still affect a quarter of a million people within 80 days with the pathogen Sars- Connect the CoV-2. After all, this corresponds to a reduction of almost 80 percent.
The team led by Alex Cook from the National University of Singapore used a simulation program for the calculations, which actually provides models for the spread of flu viruses. 100 cases of infection in the population were assumed, the number of cases was calculated 80 days later. The epidemiologists ran through four scenarios, each valid for two weeks.
In the first scenario, only sick people and their families are sent to quarantine. In the second scenario, all schools are also closed. In the third scenario, schools remain open, but half of the working population works from the home office – in addition there is the quarantine for infected people and their families. In the fourth scenario – in addition to the quarantine regulation – all schools are closed and at the same time work in the home office is made possible for half of the population – similar to Germany. All of these measures will be implemented for 14 days.
Without these regulations, according to the study, around a third of the population in Singapore would fall ill within 80 days – provided the transmission rate of the virus is particularly high. The transmission rate – in technical jargon basic reproduction number – is the number of infections that come from a single infected person. How much Sars-CoV-2 is transmitted has not yet been determined exactly. The Robert Koch Institute writes that various studies indicate values between 2.4 and 3.3. The Singapore authors therefore calculated three different values: low (1.5), moderate (2) and high (2.5).
With low transmission and a combination of all three measures – quarantine, school closings and home office regulations – it is possible that the number of infected people will only increase to 1,800 after 80 days, the scientists said.
At the highest transmission rate, the combination of the three measures can still reduce the number of infected people by around 80 percent, so that instead of 1.2 million, only 258,000 infected people would have to be accepted. In this case, however, if one only ordered quarantine for those affected and refrained from further interventions in everyday life, more than half a million infected people would still have to be expected.
The questioning of the different scenarios is of particular importance for Singapore, because so far no schools have been closed in the state, and – at least until the beginning of the week – there were no nationwide rules for working in the home office. In general, a lot of tests are carried out in Singapore, infected people are isolated, and people – also with the help of social media and smartphones – are called on to keep their distance. According to Johns Hopkins University, there were around 560 confirmed cases in the city-state as of Wednesday.
However, the significance of the study is limited by a number of factors, the scientists concede. So it is not considered how infected people entering the country influence the infection process. In addition, many properties of the Sars-CoV-2 pathogen are still unknown. In addition, it makes a decisive difference how many people are infected asymptomatically – i.e. show no signs of disease. You could spread the virus more.
The scientists initially expected 7.5 percent asymptomatic infected. When they increased the proportion of these asymptomatic cases to 50 percent, the epidemic could no longer be easily controlled, even when all measures were combined. Even with the lowest transmission rate of only 1.5, the number of infected people rose to almost 280,000 after 80 days despite using all three measures to reduce contacts.
In general, the team still sees a lot of need for clarification: “The optimal times for the implementation of each measure and their duration in order to achieve long-term control of the epidemic should be researched.” In principle, Cook emphasizes, the study can also provide data to politicians in other countries to take measures to contain the pandemic.
In an accompanying comment, epidemiologists Joseph Lewnard and Nathan Lo from the University of California at Berkeley and San Francisco describe the scientific basis for measures that lead to more social distance and contain the epidemic as “resilient”. At the same time, they call for ethical aspects to be taken into account: they recommend policies that increasingly take care of economically disadvantaged groups. This includes people who are at risk of losing income or jobs, but also homeless people, prisoners and people who are illegally staying in a country.