Another potential drawback, is that the centralized approach may eat up more power. Apple’s solution lets the contact tracing happen in the background, but the UK’s app has to be woken up every time the device detects another nearby device running the same software, BBC explains.

By choosing the centralized approach, the NHS is aligning more with Australia than some of its EU counterparts. Australia’s app, which was released over the weekend, uses a mix of Bluetooth and stored contact data on both the app and servers. Germany, on the other hand, has switched its stance and is now pursuing a decentralized architecture, as are Austria, Estonia and Switzerland.

So far, the European Commission and the EU’s data protection watchdog support both models but note that the differences aren’t entirely clear, EUobserver reports. In either case, the challenge will be getting enough widespread adoption for the apps to be effective.