英国 NHSX（国民保健サービス・デジタル）はドイツ等と異なりApple-Google APIを使用せず集中管理方式の連絡先追跡システムにする？

こんにちは、丸山満彦です。

英国 NHSX（国民保健サービス・デジタル）はドイツ等と異なりApple-Google APIを使用せず集中管理方式の連絡先追跡システムにするとの報道がありますね。。。

ドイツ、スイス、エストニアは分散型を指向し、英国、フランスは集中型を指向するという感じですかね。。。

管理がしやすいという問題もあるし、システムを簡単に作れるというのも要素の一つになっているようですね。

国民が使うかどうかの問題（バッテリーのもちも含めて）もあるし、簡単には決まらないのかもしれませんね。。。

● BBC

・2020.04.27 NHS rejects Apple-Google coronavirus app plan

● Computing

・2020.04.28 NHS rejects Apple-Google API in favour of centralised contact tracing system

● BBC

・2020.04.27 NHS rejects Apple-Google coronavirus app plan

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Centralised matching

Contact-tracing apps are designed to automatically alert people to whether they are at high risk of having the virus, based on whether someone else they were recently near to has been diagnosed with it.

They work by logging each time two people are within a certain distance of each other for longer than a specified amount of time.

When one user registers themselves as being infected, a cascade of alerts is automatically sent out to everyone else they could have passed it on to - possibly advising them to go into quarantine and/or get tested themselves.

Like the authorities in many other countries, NHSX has opted to use wireless Bluetooth transmissions to keep track of each qualifying meeting, and has said that the alerts will be sent anonymously, so that users do not know who triggered them.

It has opted for a "centralised model" to achieve this - meaning that the matching process, which works out which phones to send alerts to - happens on a computer server.

This contrasts with Apple and Google's "decentralised" approach - where the matches take place on users' handsets.

The tech giants believe their effort provides more privacy, as it limits the ability of either the authorities or a hacker to use the computer server logs to track specific individuals and identify their social interactions.

But NHSX believes a centralised system will give it more insight into Covid-19's spread, and therefore how to evolve the app accordingly.

"One of the advantages is that it's easier to audit the system and adapt it more quickly as scientific evidence accumulates," Prof Christophe Fraser, one of the epidemiologists advising NHSX, told the BBC.

"The principal aim is to give notifications to people who are most at risk of having got infected, and not to people who are much lower risk.

"It's probably easier to do that with a centralised system."
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● Computing

・2020.04.28 NHS rejects Apple-Google API in favour of centralised contact tracing system

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The NHS had earlier said that it would use Apple-Google API in its upcoming contract tracing app, but it has since changed its mind.

"Engineers have met several core challenges for the app to meet public health needs and support detection of contact events sufficiently well, including when the app is in the background, without excessively affecting battery life," a spokeswoman for NHSX, the digital innovation unit of NHS, told the BBC.

Apple and Google are expected to launch their contact tracing API to developers on Tuesday. Their solution uses a decentralised approach to address privacy concerns and battery usage should also be lower.

The API will enable governments to create apps that are capable of detecting when two mobile phones come close to one another. When an individual is identified as being infected with coronavirus, their smartphone will send alerts - using mobile-to-mobile Bluetooth communication - to all people with whom they had come in contact with.

The UK, however, prefers a centralised solution, which it believes, will provide more insight into how the virus is spreading in various cities.

Such an approach will also allow government officials to have more control over who receives notifications. NHSX says that it will be able to analyse the data and adapt the system more quickly if information is held on a centralised system. However, other countries including Germany, Switzerland and Estonia are pursuing a decentralised approach.
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