The study found that avoiding infection with the Corona virus was more than just maintaining a two-metre distance

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How likely are you to get it? Covid-19 After exposure to an infected person? This has been a question on many people’s minds during the pandemic, and a group of researchers in the UK have finally found an answer.

Researchers from the Nuffield Department of Medicine at the University of Oxford analyzed data from 7 million people in England and Wales who, during the health emergency, were notified by the country’s NHS COVID-19 app that they had been in contact with an infected person.

The goal was to find out how many people alerted had actually been infected with SARS-CoV-2.

The NHS COVID-19 app, which closed in April 2023, allowed people who downloaded it to let others know they were infected.

At the same time, the app will send an alert to users if they are in close proximity to an infected person (based on non-mandatory reporting to the app). People will then have to either isolate themselves or get tested.

The mission of Luca Ferretti, the lead researcher on the Oxford University study published in the journal Nature this month, and his colleagues was to understand whether the app was working properly.

Did you notify people when there was a reasonable risk? The short answer is yes. But researchers discovered much more than that.

“The app was sending to our servers anonymous information about who had been notified of the risks, which people had been tested, who had a positive result, and information about the specific contact: duration, proximity,” Ferretti says. Euronews Next.

“We looked at what the app calculated as an individual’s risk, in terms of distance and duration, and it turned out that the two were really closely linked,” he says.

Duration versus distance

The researchers took advantage of this “treasure trove” of information to study the relationship between distance and duration of encounter with an infected person to see how this would affect someone’s risk of infection.

It turns out that duration is just as important as distance, if not more.

“Everyone was focused on distance. There was a one or two meter distance rule in shops and stations. But distance should never have been the focus because as we know now, the reality is more nuanced than that,” Ferretti said.

“Once you’re within a short distance of someone, it’s the duration that matters. If you’re exposed for 10 seconds, you’re certainly not going to have any luck with particles from the infected person’s mouth getting into your mouth or nose. But if you’re there for an hour, of course you’re going to have “Your luck is 60 times per minute.”

The researchers found that longer exposure at greater distances had a similar risk as shorter exposure at closer distances.

There is no golden rule about how much time you can spend with an infected person before you get COVID-19, as this can change depending on what the infected person does. For example, if a person coughs a lot, the other person will have greater chances of getting infected.

But the more time a person spends with someone else who is sick, the more likely they are to become ill, even if they maintain a distance of two meters at all times.

“In fact, what we’re seeing is that a lot of the people who got sick were people who we assumed were households because they were staying together for more than 8 hours,” Ferretti said.

“These represented approximately 6 percent of communications and 40 percent of transmissions.”

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What can we learn from this?

For Ferretti, the lesson we can draw from this study is that duration will be important for combating one or the next pandemic.

“Of course, distance still matters, but once that is determined, we need to talk about duration,” he says.

The duration of contact with an infected person is “something that frankly was not accounted for in the pandemic response, and should have been taken into account,” Ferretti says.

The researcher says that in the era of big data, we must be able to use the latest technologies to develop an epidemiological tool that will help us combat the spread of new pathogens.

But the researcher is concerned that not enough is being done to direct the knowledge gained during the epidemic towards fighting the next one.

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“I will not condemn anyone or anyone who wants to forget about Covid,” he said. “I’m more concerned with the fact that policymakers have decided to forget about it at the institutional level because that brings us to the point where all the knowledge and skills we’ve acquired are gone.”