Frequently Asked Questions

Your Safe Score tells you if your Safe2 app is aware of any symptoms, test results, or potential exposures to COVID-19. If you have been symptom-free and haven’t crossed paths with anyone that has symptoms or a positive test result, your score will be high and in the “Healthy” status range. If you have crossed paths with others that have confirmed or likely COVID, if you’ve experienced symptoms, or if you have tested positive, your score will be lower in the “Uncertain,” “At-Risk,” or “Confirmed” status ranges respectively.

Your Safe Score exists only on your phone. No one can see it unless you show it to them.

A Safe2 community is a group of people who want to use the Safe2 COVID app. Safe2 communities are groups like churches, campuses, companies, counties, and tribal communities.

The lives and livelihoods in our communities depend on it. Just like you care about the health and wellness of your friends and family, other people care too. The sooner Safe2 is aware of a potential COVID infection, the sooner it can alert others that may have been affected and close off a potential branch of community spreading.

Asymptomatic carriers are identified based on the COVID infections surrounding them. When COVID infections later arise for several locations and contacts a user has interacted with, their Safe2 app notices and alerts its user they are a likely asymptomatic carrier. Once identified, the user is encouraged to self-isolate and get tested. Their Safe2 app then updates any contact interactions and visited locations for the times they were there so that other visitors get alerted too.

Users that indicate they have no symptoms when they actually do can still be detected as likely asymptomatic carriers. (See the question: How does Safe2 detect asymptomatic carriers?)

Your Safe2 app remembers close contacts and locations you have visited for more than 5 minutes, storing them on your mobile phone. If you experience a possible COVID exposure (either you have symptoms or a positive test result or cross paths with someone that does), the Safe2 app sends an anonymized copy of each location visit and contact made, only from your likely contagious period, along with an indication of your exposure status. This allows other users to know when they may have been exposed as well. No data relates to any user identifier and no two data entries relate to each other.

User Safe Score algorithms are based on CDC guidance and get impacted by your test results and self-assessments as well as any location visits and close contacts that indicate COVID exposure. If you have had no symptoms, negative test results, or exposure to those that do, your score should be in the “Healthy” range (76-100). If you have been exposed to someone with symptoms but don’t have symptoms yourself, your score will be in the “Unknown” range (51-75). If you have symptoms or are a likely asymptomatic carrier, your score will be in the “At-Risk” range (26-50). If you have tested positive, your score will be in the “Confirmed” range (1-25).

When a user is detected as a likely asymptomatic carrier, the more close contacts or visited locations they have interacted with that later revealed indication of COVID exposure, the greater the impact on the user’s score.

To raise your Safe Score from Confirmed, At-Risk, or Uncertain status, you must test negative, wait 14 days, or experience 5 days of no symptoms after at least 3 days of symptoms. To raise your Safe Score in the Healthy status range, you will need to figure out how to reduce the number of location visits and close contacts with possible exposures in the future.

Anyone can see the exposure level of a location on the Safe2 COVID App hotspot map.

Location Safe Scores are impacted by the status of any visitors (e.g. employees, customers) that indicate COVID exposure in the last 3 days. The score then gets adjusted slightly lower based on how many COVID exposure visits have been recorded in the last 3 days.

Some may be upset. Others will be grateful to get informed their location may temporarily be unsafe for employees and customers so they can clean appropriately. Businesses are aware that they need to remain vigilant about keeping their employees and customers healthy. 

Currently, the business must have 3 days of visits with no potential COVID exposure. However, we are developing methods for more quickly restoring a location to Healthy status after appropriate cleaning.

For location visits and close-contacts, Safe2 stores data only on the user’s phone with one exception. When it’s likely a user has been exposed to COVID-19, the app sends anonymized location and score data, only for likely contagious periods, to a central server so other users can be alerted.

Safe2 anonymization uses proven technology so that no one but you can determine that your location visits are yours or that they are even related. Your mobile phone is the only thing that can determine your data entries are yours or that they are related. In the event our database server is compromised, your identity, travel patterns, and contacts would remain totally obscured. And if someone gains access to your phone, they will only be able to see your location visits and self assessments for the last 14 days.

Safe2 treats self-assessment symptom data and test results very carefully. It stores all self-assessment symptom data and test results in your phone’s secure enclave and flags it to not be backed up by iCloud or Google.

Frequently Asked Technical Questions

COVID spreads too fast for manual contact tracing and there aren’t enough personnel to manage tracing during waves of exponential infection. Safe2 reduces notification time from days to hours and can scale quickly during large waves of infection. Safe2 asks users that are notified of potential exposure to connect into their local public health manual contact tracing efforts as well as allowing those that test positive to enter known close contacts into a private notification system which also provides connection to manual contact tracing efforts.

Traditional contact tracing is initiated following a positive test result. It requires about 120 hours of manual work per infected person (i.e. “index case”). Interviews, investigations, and communication comprise much of the work and there are critically important human considerations for many steps of the process. Unfortunately, even with many people working on one index case, many contacts are not identified or informed until 2-3 days after the index case positive result. During this time others may get infected.

Safe2 supports traditional contact tracing, making it more efficient and reducing time to initial notification. When a user first reports symptoms, their contacts are privately alerted so they can take precautions to protect others. When a test result is available, close contacts are alerted within an hour about the positive or negative result. If positive, the contacts are invited to opt-into traditional contact tracing communications. Contact tracers will receive calls from several contacts using Safe2, often even before interviewing the index case. This reduces the time and effort needed for investigation, identification, and initiating communication – but most importantly it reduces the time during which contacts might be unknowingly infecting their family, friends, co-workers, & community.

Throughout, Safe2 data and processes preserve all users’ privacy. If this sounds too good to be true, have your technical advisors review our open source Safe2 Protocol to understand how it all works.

Safe2 wants to give our communities the best chance of keeping COVID under control. In many places, test kits are in short supply, results can take days, and they aren’t always accurate. Some doctors rely on symptoms even when tests are negative. Detecting possible COVID infections via both test results and self-assessments allows for the earliest possible alerts that inform users how they can keep their friends, family, co-workers, and communities safe. As we learn more about COVID-19 and find improved methods of interaction, we will integrate them to inform better selective social distancing.

Bluetooth and GPS have different strengths and weaknesses, but both are useful in combating the spread of COVID.

There are three known COVID transmission methods: droplet, aerosol, and surface transmission. Respiratory droplet transmission often happens when you’re talking to someone up close. Aerosol transmission happens when someone coughs or sneezes and COVID remains lingering in the air for up to 3 hours for others to inhale. Surface transmission happens when someone touches a surface where COVID landed and then touches their eyes, nose, or mouth. COVID can remain infectious on some surfaces for up to 3 days.

Bluetooth proximity detection is excellent for detecting both droplet and shared-presence aerosol transmission opportunities while GPS is useful for detecting when lingering aerosol or surface transmission may have occurred.




(from talking)


(from sneezing)


(from touching)

Bluetooth Proximity




GPS Location Visits




Yes, we will. Whether you talked with close contacts that later discovered they were infected or you visited locations where people left aerosols or surface COVID behind, you still may not have contracted the virus. Unfortunately, there is no way for either humans or the Safe2 app to tell if they were infected unless you later develop symptoms, test positive, or show signs of being an asymptomatic carrier.

Therefore, Safe2 notifies any users who have had potential exposure so they can choose whether to self-isolate or get tested rather than take risks with spreading the virus further. COVID is a very contagious virus and infections can cost lives. We need to play it safe until we understand it better. Masks, gloves, washing hands, and thoughtful actions can help keep you safe, but there are no guarantees. Life with COVID is different. As we reopen our economies, we need to accept that we may have to act differently and sacrifice from time to time.

The truth is, no one knows how much contact with the virus is required to get infected. Current social distancing guidance of less than 6ft for 15min is based on similar guidance from the 1940’s and 50’s and continues to be called into question.

We record close contacts for people that spend 5min in under ~10ft proximity and we notify everyone that has visited a location that learns of likely COVID exposure. While this is more conservative than current guidance, we want to carefully guard against new waves of exponential infection. If we underestimate COVID, our communities will suffer. More death, more sickness, and more mass-isolation.

Safe2 plans to relax its estimates and calculations over time as we see more communities returning to sustained economic activity without new infection waves. As more communities show that they successfully sense and respond to new COVID infections without seeing large waves of growth, Safe2 will loosen its estimates and calculations.

Yes, we will. We are dedicated to using the best scientifically-proven methods available. As soon as the CDC indicates there are new trusted methods for COVID detection, we will explore how Safe2 can integrate them to better inform your Safe Score.