As the seemingly never-ending coronavirus pandemic escalated this fall, cellphones in Colorado started buzzing more frequently with an alert: “You may have been exposed.”
The state’s opt-in COVID-19 exposure notification system has been around for a year, but a system upgrade — combined with the latest wave of cases — recently made for a busy few weeks for the app.
Over two weeks in mid-November, almost 5,000 people shared their COVID-19 positive status in the notification system and about 50,000 people clicked through to read instructions after receiving an exposure alert on their smartphones, according to data from the state health department.
The 4,963 people who “claimed a code,” meaning they shared news of a positive coronavirus test, represented 12% of the total 41,751 people who tested positive for the virus statewide during that two-week timeframe.
In all, Colorado has seen a 31% increase in reporting positive cases via the system since the state enabled a self-report feature that allows people to anonymously post their own result from at-home tests or testing sites. Before the change, people had to wait for the state system to process the positive test and send them a code, which is required to initiate an alert.
Since August, people have been able to generate their own code, pop it in the app and allow the system to notify everyone they had close contact with in the prior 14 days.
The alert pings the phones of people the infected person got close to at a grocery store, gas station, restaurant, office or basically anywhere. And the person receiving the push notification — and the dramatic notice to “Quarantine Immediately” — will not know where or when that encounter took place.
What if you receive an alert?
The vague details and timeframe behind an exposure notification raise an important question: How seriously should a person take an alert, especially last month when one in about 50 Coloradans had an infectious case of the coronavirus and every visit to a public place runs a high risk of exposure?
The app, for example, doesn’t know whether you wore a mask to the grocery store. It also doesn’t know if you’re unvaccinated or have already had a booster shot.
It does, however, know how long you were near the person with COVID-19 and within how many feet, and whether you were indoors or outside.
The best thing to do, according to state health officials, is stop by a testing center for a free COVID-19 test. The next best thing is to avoid spending time with other people for the next week or 10 days.
Even though someone who was outside has a lower risk of catching the virus, the delta variant — responsible for nearly all infections in Colorado this fall — is much more transmissible than previous variants, health officials said. The latest variant, called omicron, has been detected in Colorado.
No matter outside or inside, “we encourage anyone who receives an alert to get tested at one of the more than 120 free community sites around the state,” a health department spokesman said in an email to The Sun.
The Colorado Department of Public Health and Environment recommends that people wait three to five days after receiving a notification before getting a test, and to get tested regardless of any symptoms.
And if you test positive? Use the app to generate a code and pass it along.
How does the app work?
More than 3 million people have signed up to receive alerts since the state health department first announced the system in October 2020.
When people who are signed up for the notifications are near each other, their phones exchange “tokens” via Bluetooth. If one of those people tests positive for COVID-19 within the next 14 days and chooses to anonymously share their positive result in the app, others who had close contact with the infected person receive an alert.
The app does not use GPS or record a person’s location.
Its signal can reach other phones within 30 to 100 feet or farther, depending on obstructions — like walls. But much more goes into the exposure notification than just being in the same building or on the same trail as someone who has tested positive for coronavirus.
The system uses “exposure risk value” — which takes into account the proximity, length of time of exposure, and the ill person’s level of infectiousness based on when they received a positive test — to determine whether a person should get an alert. The scale goes from zero to 250.
Is the notification system helping?
About 50,000 people read the quarantine instructions in the two-week period ending in late November after getting an alert, but what did they do about it?
There’s no way to know for sure, according to state health officials, but they’re taking it as a good sign that more people are using the app since the self-report feature was added. Colorado was the first in the country to do that, by the way.
“Thousands of Coloradans have sent notifications, and that likely means that someone who did not know they were exposed went and got tested and quarantined so as not to expose other people,” a Colorado Department of Public Health and Environment spokesman said. The department considers the notification system one more tool in its fight against the virus, along with vaccination, mask-wearing and contact tracing.
The change to allow self-reporting has helped improve what was a tough start for the app, which garnered widespread complaints from people who said they had tested positive but then waited days or even weeks for the state to send them a code.
There’s no way to know whether a person who received a notification got a COVID-19 test. When a person sends an exposure notification using their code, the state does not see how many people were notified, their names, locations, phone numbers or any other identifying information.
That means the state does not know the total number of people who have received a notification. Officials do know that 425,000 people have clicked through to read the “quarantine immediately” message in the last year, and 53,228 people used a code to notify people they were sick. Also, 3,603 people have used the self-report feature since it became available three months ago.
How much did the app cost Colorado?
The exposure notification system, created by Apple and Google, was free for public health agencies to use, so the state did not spend money on its development or maintenance. But Colorado has spent $750,000 in federal coronavirus relief aid marketing the service.
In addition, a few state employees have been assigned to troubleshoot and answer questions about the notification system.
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