What is StopCoro?

StopCoro is a coronavirus (COVID-19) contact tracing app which uses Bluetooth technology to help its users know whether or not they had contact with an infected person.
StopCoro can tell with certainty which person has been in direct contact with the user and which has not (for example, by being behind a wall or slab).
It is a contact tracing app developed by TonkaIn in Cameroon.
We will present here:

What is StopCoro's case scenario?

When friends visit your home or you go out to public areas, you can now create a log of friends and other people you meet in public gatherings.  StopCoro assigns a unique anonymous identifier to you when you register. It could be that one of them is infected by the virus but in incubation phase and shows no symptoms. Your friend and the other people you meet do not know that they are infected.

Many days later one of your friends, or one of the contacts you have met starts feeling the coronavirus (COVID-19) symptoms.

This person goes to the testing laboratory where he is diagnosed and tested positive with the coronavirus (COVID-19).

The medical doctor then enters this person's anonymous StopCoro identifier to notify StopCoro server.

An alert will then be sent to you and everyone else this person had been in contact with in the previous 14 days, urging them to isolate themselves and call  the helpline.


Can you remember everyone you met during the past 14 days? NO. StopCoro will do it for you making it easier to break the chain of contamination.

StopCoro can say with certainty which signal has been in direct contact with the user and which one has not been (by being for example behind a wall or slab).

Stopcoro enables its users create a log of people with whom they came in contact while strolling, in the taxi, in the bus, in the plane, at work, or in the market, this without the collection of personal information.

If a user is infected with the virus, he notifies StopCoro which then reaches out to every one of the anonymous contacts he registered before, urging them to isolate themselves. Other users coming in contact with this tagged infected identifier are informed of the presence of a coronavirus carrier around, advising them to take proper measures in order to break the contamination chain.

Help stop the spread of coronavirus (COVID-19)!

Protect yourself and protect others!


How does StopCoro work?

1- Download StopCoro app from Google app store (Apple version coming soon)


2- Connect to the internet and launch the StopCoro app

When the application is launched, the following page is displayed for a few seconds.

At the very first launch of the application you need to be connected to the internet in order to get your application ID (This unique identifier is anonymous and is only linked to the StopCoro app and not to your name. This is the only information StopCoro needs to log all your contacts and trace them in case of an infection).

3- Install the app and Enable the Bluetooth

After you install and launch the app, you will receive a message asking you to allow the activation of your Bluetooth. StopCoro uses Bluetooth signals to log your contacts devices. It does not track GPS signals.
Your Bluetooth will be enabled just for the time you need it to log your contacts. This prevents your Bluetooth from being on all the time, at the mercy of hacker's attack.

4- Enable location sharing

Why does location sharing have to be done on Android devices?
Android operating systems requests the switch of location sharing when devices want to share anonymous identifiers (token) without pairing. StopCoro doesn't query or process your location.
Your location will be enabled just for the time you need it to log your contacts.

5- Log contacts

You can use StopCoro to create a log of people with whom you came into contact. It helps you protect yourself from the COVID-19 pandemic and offers you the possibility to trace the coronavirus (COVID-19) contamination chain.

6- Alert registered contacts in case of infection


In case you are diagnosed Coronavirus (COVID-19) positif, you notify the StopCoro server which then reaches out to everyone of the anonymous contacts you had registered during the past 14 days, urging them to isolate themselves

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Can the police use StopCoro to search for infected people?

With StopCoro, Bluetooth does not run in the background. You switch on your Bluetooth only the time to log your contacts (people with whom you physically met).
In our desire to develop a solution that avoids the detection and stigmatization of patients infected with coronavirus (COVID-19), we noticed that if the Bluetooth is always on, the user is not anonymous in certain situations. The population or the police can use this scenario to track patients. Just go to a suspicious area and start looking for Bluetooth devices of people who are sick. The application will detect all patients. Why? Because this scenario allows the application to run in the background. This is one of the reasons that prompted us to stop the development of this scenario. Being infected with the coronavirus (COVID-19) does not mean you are a danger to the population, especially if you respect the rules established by the World Health Organization (WHO) and the Ministry of Health.

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 Is StopCoro accurate?

Yes! Stopcoro enables you to anonymously register people with whom you physically met.

Distance measurement via Bluetooth is not accurate.

Many communication technologies are able to detect signals emitted by other devices, but are not able to make a clear difference between signals in direct contact and those behind a wall or slab. This is not the case with Stopcoro. Stopocoro is capable of accurately determining and saying with certainty which signal is or has been in direct contact with you and which one is or has not been (by being for example behind a wall or slab) . This feature is very important as it enables you to know with assurance who has been in direct contact with you and who has not. 

Let's imagine you live in a multi-story building. Your apartment is on the fourth floor, you receive a visit from friends and everyone launches the application. At the same time, the neighbor who is on the third floor, less than two meters away from you does same. The only thing that separates both of you is the slab. In this case, your neighbor's application will register the people at your home as those with whom you had direct physical contact. Which is not correct. What will happen if one of your neighbors is tested positive? The server will send you a message that you were in physical contact with someone infected with the coronavirus. Imagine that after respecting the health rules proper to Coronavirus (COVID-19) patients thinking that you are infected, you latter on discover that you had never been infected with the virus! What psychological and material damage would it have caused if you never had a diagnostic test? With Bluetooth it is not possible to determine whether or not there has been direct physical contact with someone. StopCoro is a solution that will allow physical contacts to be determined with precision.

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Bluetooth technology searches for all devices

If you are at the station and launch the application, it will search for all the devices which are more than 10 meters from you depending on its power. If the bus leaves in two minutes and the application detects a suspicious case around you, you will not know that this suspicious case does not constitute a danger for you. So, you will get a false alert that will prevent you from traveling. We have found a possible solution to this. The solution is StopCoro which is more reliable and will not give false alerts.

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Why should you use StopCoro?

  • All data collected is anonymous to protect the privacy of the users.
    • This prevents coronavirus (COVID-19) carriers from being stigmatised.
    • It also eradicates all possible attempts to use their data for other purposes (e.g. spying, targeted advertisement, geolocation,). StopCoro is not linked to the user's phone number. Therfore does not allow user identification.
  • Moreover its development is not financed by a government as it is the case in some countries. This prevents all governments from using StopCoro to spy on citizens.
  • StopCoro is developed by Africans to meet African health needs, which are different from those of other continents.

Help stop the spread of coronavirus(COVID-19) ! 
Protect your relatives, others and yourselves ! 
Take the fight against coronavirus (COVID-19) into your hands and together, let's stop it spread using StopCoro!

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What are the benefits of using StopCoro for healthcare workers and how does it help stop the spread of coronavirus (COVID-19) in Africa?
The fact that manual contact tracing is tedious and time consuming favors the rapid spread of the pandemic. This is not the case with StopCoro, which provides on the other hand a fast and easy contact tracing.

  • In most African countries, home addresses do not exist. This makes it difficult to locate, or accurately trace out the contamination chain. With Stopcoro, finding exposed people will not be a problem any longer, simply because Stopcoro can help reach to them easily through their anonymous identifiers.
  • With Stopcoro, the difficulties faced by healthcare workers in trying to communicate with exposed people are fixed too. The random blinking nature of electricity and telephone network is no more a big deal. There is no need for the healthcare workers to call several times before being able to communicate with people who were exposed to the disease. Stopcoro does that for him, and does it continually (24h/24h).  StopCoro can reach your exposed friends faster than healthcare personnel  and therefore reduces the spread of COVID-19 in Africa.
  • Problems resulting from the limited number of trained staff, able to manage the growing number of people with COVID-19 are resolved, as StopCoro server can be easily scaled and don’t need extra training for the tracing of exposed contacts.

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Who develops StopCoro?

StopCoro is developed by TonkaIn which is a research and development institute for embedded and computer systems with headquarters in Bangangté, Cameroon.

Is the application free and open source?

No. The reason is that we are developing StopCoro under high pressure (22nd April 2020), because we have to deliver it quickly in order to save as many lives as possible. It is a race against time, to try to reduce the effects of the virus on the African population. We have stopped all our projects to devote ourselves solely to this project. We are developing the functionalities, security and testing of the application. We don't have time to specify and document the development as it is done in an open source project.

Given the urgency of the coronavirus (COVID-19) in Africa and the fact that our health systems are not adequate enough to receive a large number of patients in case of an exponential spread of the virus, please download the application, use it and give us your feedback so that we can improve it and add more features.

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What motivated us to tackle the coronavirus (COVID-19) spread ?

Seeing what was reported on TV stations and social media about the state of coronavirus (COVID-19) spread in Cameroon, we said we must take our responsibilities in relation to this pandemic. We saw people loosing their lives around us everyday and we could no longer continue to do research and development while the virus is spreading exponentially. For this reason, on April 4, 2020 we started discussing about what should be our contribution for the fight against the spread of the virus in our country and in Africa in general. We spent the whole weekend brainstorming about possible solutions, based on the technology we mastered. On April 6, 2020 we decided to stop the research and development of integrated circuits and IT solutions to devote ourselves solely to find solutions to combat the spread of the coronavirus (COVID-19). We came out with scenarios 1 and 2. That is how everything started. Why did we decide to use the technology we mastered? Simply because it is a race against the time. Using a new technology means loosing time while learning and this may take months. Not doing something would have been very bad for our values.

Could StopCoro be used in all african countries?

Yes. It will depend on the availability of the health authorities in each country. You can also get them to join the project and help accelerate the deployment in your country and save lives.

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Last modified: 18th Mai 2020


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