Pennsylvania’s Exposure Notification Mobile App

A public health perspective of digital contact tracing in 

COVID-19 using Bluetooth-enabled technology 

January 26, 2021

Lead 

Meghna Patel, MHA

Deputy Secretary for Health Resources and Services
Exposure Notification 

Exposure Notification Service Announced in April 2020 by Apple and Google

Enhances the current traditional contact tracing efforts 

Unknown and unfamiliar person interactions 

Reached out to Australia, Singapore, Ireland, Germany, etc. – learned what 

they were doing

Started multi-state coordination meetings 

Selected NearForm Inc. (Ireland, Northern Ireland, Scotland, Gibraltar 

govt.’s)

Partnered with Delaware, New Jersey and New York

Partnered with UPenn, and MIT Lincoln Labs through CDC

Piloted with several state agencies before launch

Background
About

Pennsylvania population

12.8 million

Assumption that about ~80% of U.S adults have a smartphone* 

~19% of the population is over 65+ years 

~21% of the population is under 18 years

COVID Alert PA App

Launched September 22, 2020

Collab between 4 states (NY, NJ, PA and DE)

Almost similar features of the app 

765k downloads so far since launch (~7.6% of eligible population)

COVID Symptom Check-in feature (daily average of 55,000 individuals check-in)

Pennsylvania Public Health

State public health department (~250 case investigators)

Six county health departments

Four municipal health departments

* Pew Research Center – Mobile Fact Sheet survey June 2019.
Integrated with Association of Public Health Laboratory (APHL) server so we are 

interoperable with below states that use Exposure Notification Service of Apple/Google. 

More states continue to add each week:

• Alabama

• California

• Colorado

• Connecticut

• Delaware

• Washington D.C.

• Hawaii

• Maryland

• Michigan

• Minnesota

• Nevada

• New York

• New Jersey

• North Dakota

• North Carolina

• Virginia

• Washington

• Wisconsin

• Wyoming; and

Pilot only – Oregon

Interoperability
Exposure Notification 

Bluetooth is a wireless technology - reacts aggressive in a closed metal 

environment (6 feet could show as 4 feet)*

Does not know if someone is wearing a mask

Does not know if phone devices are close enough but devices owners 

are 6 feet apart

Public trust of the technology in the time of a misinformation 

epidemic

* Because it is replicating an indoor setting, it is still best to err on the side of caution for an 

exposure alert if individuals are exposed to someone with COVID-19. 

Limitations
pa.gov/covid

Key Messages and Logo

Social Media Toolkit

Printable and Digital 

Resources

Stickers

Postcards

Posters
Available for ages 13 or older
Exposure Alert – call back feature

Callback feature –

Important for close contacts to reach us so that we can 

perform contact tracing and close monitoring.
Exposure Notification 

“Ideal” Workflow

Case

Case 

Investigator

Close

contacts

Close

contacts Close

contacts

Contact 

Tracer

Contact 

Tracer

Reach out to the COVID-19 

positive case in 24-72 

hours of a positive test 

result in our system

COVID-19 

turnaround 

time is rapid

Lab reports are 

submitted timely with 

complete information 

Reach out to the 

close contacts within 

24-48 hours to help 

cut the chain of 

transmission

Cases and close 

contacts pick up 

the phone
Exposure Notification Questions to COVID-19 positive cases:

1. Was the patient alerted by the COVID Alert phone app that 

they were exposed to a person diagnosed with COVID-19? 

(Yes/No)

2. Do they have the COVID Alert PA app installed on their cell 

phone? (Yes/No)

1. If yes, are you willing to help others and alert them that they may have been 

in close contact with someone who was tested positive? 

3. Did the patient agree to upload the Random ID? (Yes/No)

Case Investigator Workflow – Questions related to the App 

Note:

1. Initially these questions were not required, then we made them required.

2. We removed the “willingness” question in December 2020 because most cases 

with app responded that the app was mostly for them to get alerts.
Table 1

Metrics

Average Daily Responses

Yes: 4

No: 724

0

200

400

600

800

1000

1200

1400

September 22, 2020 October 22, 2020 November 22, 2020 December 22, 2020 January 22, 2021

COVID-19 positive individuals got tested because of the Exposure Alert from the app

Yes No

Unclear if the all the COVID-19 positive individuals 

understood this question properly.
Exposure Notification 

Metrics

Average Daily Responses 

Yes: 17

No: 566

Only ~3% have the app installed

0

200

400

600

800

1000

1200

September 22, 2020 October 22, 2020 November 22, 2020 December 22, 2020 January 22, 2021

COVID-19 positive individuals that have the app installed

Yes No

Table 2
Exposure Notification 

Metrics

0

20

40

60

80

100

120

September 22, 2020 October 22, 2020 November 22, 2020 December 22, 2020 January 22, 2021

Random ID upload behavior

6-digit Code Submitted to Case Case Agreed to Upload Actual Random ID uploaded

Note: Whether the case agrees to upload the random ID was not collected for the 1st month.

Table 3

Learning 

curve of 

code 

generation
Exposure Notification 

Metrics

Note: These are 14 day intervals

2020-09-24 2020-10-13 2020-10-27 2020-11-10 2020-11-24 2020-12-08 2020-12-22 2021-01-05 2021-01-20

0

10

20

30

40

50

60 Exposure Alert Callback Requested Actual Random ID uploaded

Table 4
Metrics Summary

As of January 25, 2021

765,000 downloads of COVID Alert PA app

2,188 (3%) COVID-19 positive cases have the app installed (~70,807 

do not (97%))

1,032 Random ID’s uploaded (*47% of cases that have the app)

529 Exposure alerts

102 Android devices

427 iPhone devices

70 individuals requested call-back from DOH

*Average has been 50-55%
Additional findings

1 callback received exposure alert and tested positive, resulting in a 

possible asymptomatic case 

1 callback received exposure alert and tested positive, but it was 

not confirmed if the positive test was before or after an exposure 

alert due to delayed contact tracing and unclear notes. 

1 callback received exposure alert and later tested positive 25 days 

after the alert (due to the timeframe gap, we suspect positive case is not 

likely due to exposure alert)

3 callbacks reported in our disease surveillance system but received 

exposure alert outside their isolation period (more than 10-14 days 

after exposure or positive test result) 

*Contact Tracer
Average Behavioral Survey Findings

Conducted by UPenn’s Center for Health Incentives and Behavioral Economics 

Age group that responds to the survey
Average Behavioral Survey Findings

Conducted by UPenn’s Center for Health Incentives and Behavioral Economics 

Reasons why most people download the app
Lessons learned so far (and still learning...)

This technology cannot replace manual contact tracing but accelerate distribution of 

alerts to the unknown and unfamiliar contacts.

Addressing misinformation via and from legislatures, social media, news/media, op-eds, 

illustrative and influencer videos, etc.

Messaging in a 6th grade language!

This is a public health communication tool, not a data collection tool for public health 

surveillance. 

Unmanageable volume of COVID-19 cases and public hesitancy to pick up the call:

*Average weekly COVID-19 cases: ~46,700

18% of case investigations start in 24 hours

5% start within 48 hours

Roughly 16-20% of cases are investigated each week 

Weekly press release reminders to “Answer the Call”

Pandemic fatigue along with other overlapping crises – isolation leading to opioid 

epidemic and mental health crisis

Differences in public health messaging – federal, state and local

Low uptake of this technology – how to address that nationally

Opportunities for further research:

Can this technology be used for other infectious diseases

Trust in public health and the technology

Effective messaging techniques

*numbers from the 3rd wave
THANK YOU

megpatel@pa.gov

www.health.pa.gov

https://www.pa.gov/covid/