How we can prevent the next pandemic

When no vaccine is available, contact tracing is extremely important when it comes to fighting epidemics. If we can identify and isolate cases quickly, the disease cannot spread. The contacts are usually traced by asking the patients who they have met and where they have been. This is very time consuming and it is difficult to find all relevant contacts. Using technology, we could solve this problem much faster and with higher accuracy. Here is an example of how it could be done:

1. Every person in the country receives a bracelet or ankle strap with a device that detects other persons in the vicinity. It does this by broadcasting a unique ID and listening for other broadcasting devices. When another device is nearby, the ID of the other person and the time of the meeting is stored on the device.
2. If a person tests positive for the disease, the health authorities will scan the device and access the stored data. Using this information, it is relatively easy to identify persons that may have been exposed and to identify the source in this case. The persons at risk will be told to isolate themselves in their homes.

In order to make this effective, almost every person in the country must carry this device. Therefore, laws would have to be changed to force people to carry it. This may of course not be very popular but the privacy impact would arguably be far less painful than other (less effective) measures such as curfews or shutting down schools, airports and businesses.

The device would be small, light, have a short range radio module (e.g. Bluetooth or UWB), a battery and a little amount of memory. The cost of manufacturing these devices would be a tiny fraction of what other measures costs. The chips these days are very power efficient so it should not be too difficult to build the device that runs for several months before replacing the battery.

In order to limit the privacy concerns, it is worth pointing out that such a device could be made so that:

• The device only communicates with short range radio. It cannot send the stored information anywhere on its own.
• The stored information is encrypted with a key only known to the health authorities.
• The stored information is accessed only if you have been diagnosed.
• The stored information is automatically deleted after a period that equals the maximum incubation period.
• The ID that the device broadcasts can only be connected to you by the health authorities. Laws could be made so that the health authorities are not allowed to share this information with other authorities, media etc.

Questions and answers

Are the health effects really worth the privacy intrusion?
That is a question that needs to be discussed publicly, preferably in a time when there is no immediate fear of a pandemic. The answer to this question likely varies with the characteristics of the disease. Perhaps we decide to deploy it in an Ebola epidemic (mortality rate >50%) but not in an Covid-19 epidemic (mortality rate <5%).

The manufacturing and distribution of the devices will take a long time. Will it be too late to stop a pandemic?
It is probably too late to start if there already is a pandemic underway. However, it is worth noting that some diseases can return in a second wave.

How long should a person be isolated if he/she has met someone with the disease?
It is up to the health authorities to decide. If the pandemic is extremely dangerous, it is likely that the optimal isolation time is close to the maximum incubation period. However, since it is less likely that the disease was transmitted if the meeting was very brief and the device can tell how long the meetings lasted, the health authorities could chose to reduce the isolation time for people with low risk.

Has this been done before?
Contact tracking devices has been developed before. They have not yet been deployed in a larger population (as far as I know).

Will the device detect 100% of all meetings?
No, but a 100 percent detection level is not necessary in order to stop a pandemic. All it takes is to reduce the disease’s reproduction number (R0) to below 1.

Viruses can survive on surfaces for some time, which means that a disease can spread between two persons even if they don’t meet. Does this make the device useless?
Indirect transmission may occur but direct transmission is much more common. Again, we don’t need 100% transmission detection to stop a pandemic, all we need is to reduce the disease’s reproduction number to below 1.

If the pandemic is out of control, will the health authorities have the resources to test everybody with symptoms?
No. A possible solution to this problem is to let people download an app where the user can answer some questions about his/her current health. If the user has enough of the symptoms matching the disease in question, the app concludes that the user has contracted the disease, extracts the data from the device and uploads the data to the health authorities.

Since a radio signal can pass through walls, will the device erroneously register meetings e.g. neighbors in apartments or if I’m driving close to a bus?
Probably, but it should not be a big issue if there are relatively few mistakes. The mistakes can be limited since:

• The radio signal strength can be used to estimate the distance between the devices, and neighbors will appear to be further away from each other than they really are since walls reduces the signal strength.
• If a device has registered many short meetings, they can probably safely be ignored. Most of the mistaken meetings will be short.
• When a larger share of the population is infected, it is likely that the government restricts gatherings and public transportation. This will reduce erroneous meetings.

Can the battery really last several months?
Most likely. In order to save energy, the device doesn’t have to broadcast all the time but perhaps only every 10 seconds. If the device is allowed to be slightly larger and more expensive, it could be possible to use kinetic energy to charge the battery.

Is it possible for the police/criminals/stalkers to track an individual by listening on the broadcasted ID?
Anyone with a smartphone can fairly easy find out which ID a person in the vicinity broadcasts. Using the ID, it is easy to build a scanner which detects if you get close. One way to prevent this abuse is to have the device switch between many different IDs (but all IDs are known to the health authorities).

Is a separate device really necessary? Isn’t a smartphone and an app enough?
An app could possibly do the same job. There are pros and cons compared to a separate device. It is also conceivable that smartphone manufacturers could build this technology into the phones.

Is it important to have a global standard?
Many different technologies would probably be much less effective since they would not be able to identify each other.