A comparison of the different calculation methods showed that they all yield similar results. “That gives us confidence in our calculations based on new infections,” Stadler says. She and her colleagues, based at ETH Zurich as well as the University of Basel and the University Hospital Basel, among others, submitted their study for publication on the medRxiv preprint server. It should appear in a few days without going through the scientific review process.
Too early to relax the measures
Is the data encouraging enough to consider relaxing social distancing measures? “It’s too early for that,” Stadler says. The fact that the situation is currently stable is certainly positive, for example for hospitals and their capacity planning: as long as the situation remains like this, hospitals know that they will need as much capacity for new admissions in the future as they do now.
However, this does not mean the epidemic is contained. “If we lift those measures anytime soon, there’s no doubt that the virus will immediately begin spreading exponentially again,” Stadler says. Only once the peak of the epidemic is definitely far behind us can the current measures be lifted and replaced. A reproductive number well below one would be an indication that this point has been reached.
An app for contact tracing holds promise
That is the point in time at which the current drastic measures could conceivably be replaced with an effective system for identifying people who have had contact with an infected person – known as contact tracing – and, based on this, for ensuring the isolation not just of people with the infection but also of their contacts who test positive for the virus. “For this to work, the tracing process must be very fast. One way to achieve that would be with an app featuring SMS alerts, which is now being discussed,” Stadler says. However, the promise of such tracing and isolation arrangements relies on the number of patients being small. “If the previous measures were replaced by contact tracing and isolation today, I fear that many of us would receive a text message within a few days telling us we had recently been close to an infected person.”
On 20 March, the Swiss Federal Council tightened the measures further and decreed that people may meet in groups of no more than five, provided that they remain an appropriate distance apart. It is still too early to tell whether this tightening is sufficient to contain the epidemic. “That’s something we should start seeing in the next few days,” Stadler says. She and her colleagues will continue their evaluation on an ongoing basis.