Could you save lives from Covid if you knew what movies are watched around the country? Yes, if you are Yandex - largest Russian creator of numerous apps and services. We analysed this big data and found unexpected connections. It appeared that, by knowing what services are more used than the others, the city activity level can be measured. This discovery formed the basis of the tool that helped Russia save lots of lives during the Covid-19 pandemic.

When Covid-19 came to Russia, life in the cities changed. International experience showed that to slow down the spread of the virus and thus save lives people should stay home. For safety reasons and to decrease the number of social contacts, the president announced weeks off of work. But people perceived this as vacation and went out for walks, bbqs and other free-time activities. Somebody had to do something, otherwise this could result in more cases. This is when Yandex, Russia’s largest creator of many apps and services for a convenient life used by over a half of the population daily, decided to step in and use its resources to save people.

We came up with a simple idea: just as you can’t change the temperature if you don’t measure it, you can’t change the number of people on the streets if you don’t know how many are there. That is how the Self-Isolation Index was developed. This is an anonymous data-based tool that showed how well people were self-isolating in different cities. It is based on the anonymous data from over 20 Yandex services that are daily used by over a half of the population. We had to make the index clear for everyone, even children, that is why we made it in a form of a simple 5-grades scale. And to make this index more emotional, we chose to color it: red color meant the citizens were on the streets and in danger, green color meant they were at home and safe.

Yandex’s ecosystem includes dozens of services for a convenient city living, like maps, taxi, movie and music streaming, food delivery, etc. These services are used by over 60% of Russian population. Our homepage yandex.ru is the most visited page in Russian language internet with over 70mln daily views. When Covid came and the national self-isolation regime was announced, we started noticing changes in how people used our apps. We decided to use anonymous trends from our services to create an aggregate Self-Isolation Index. We replaced an indicator of city traffic, which people check at least 2 times a day, with our Index. We also placed it on yandex.ru, so it became impossible to ignore: the officials, bloggers, media and even regular users had to react to it by drawing attention to the importance of staying at home or even introducing new safety measures.

It’s impossible to notice when one person changes its behaviour, but when there are many of them, it becomes a trend. And this is what happened. Staying self-isolated, people didn't plan many routes, didn’t use metro map or order taxis. But they ordered more deliveries, read more content and news feeds, watched more movies. We compared these anonymous trends from over 85mln users of our 24 main services with the same data from before the pandemic. After all the calculations we aggregated the result into a simple 0 to 5 grades scale where 0 was equal to the regular activity on a day before the pandemic, and 5 meant most people were at home. The Index was measured in real time for 173 cities with over 100k population. We sent push notifications daily and when it changed by more than 0.3 points, so people were kept up to date.

• ~8 billion total impressions, including worldwide coverage in news, media and social platforms.

• +20mln search queries daily – Yandex became the most noticeable company in Russia during the pandemic and raised the number of Russian internet users from 57 to 60%.

• The Index became an official metric of self-isolation across Russia, as the government noticed this and started to refer to it in meetings.

• According to a research made by Higher School of Economics National Research University, the joint efforts of people and government on self-isolation helped prevent 80,000 deaths from Covid during the first two months of the pandemic.