Contact tracing

How to build a contact tracing text messaging strategy for COVID-19

  • Chris Piwinski
    Chris Piwinski
  • Jun 15, 2020

A few best practices for engaging patients and exposed contacts using SMS

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Messaging channels like SMS play a pivotal role in contact tracing as tracers inform potentially affected individuals and monitor the spread of COVID-19.

Tracers often call highly exposed contacts, but symptom tracking and notifications for those with lower exposure can be automated, saving valuable time and resources.

To effectively use messaging channels like SMS for contact tracing, it’s important to understand the task that you’re performing, compliance regulations in your region, and your options for the actual number sending the text message itself.

Let’s take a look at how you can build a framework to deliver critical messages to citizens at scale.

Common contact tracing tasks

Typically, there are two types of people tracers need to contact: patients who’ve tested positive for COVID-19, and exposed contacts identified by patients.

To communicate effectively, it’s important to consider how to deliver messages that prove legitimacy and build trust. Unfortunately, bad actors are out there trying to do harm with spam messages and nefarious links. To counteract that, always include identifying information on your organization.

Whether you’re communicating with a patient or an exposed contact, break your strategy down into contact tracing tasks. There are four main tasks within an inform-identify-monitor strategy:

  1. COVID-19 education

  2. Contact identification

  3. Contact notification

  4. Symptom tracking

Consider the effect of your outreach

Testing positive for COVID-19 is scary, and self-isolation can add to the stress. Uncertainty can lead people to follow worst-case-scenario thought patterns, but you can address that through information.


Contact education

When a patient tests positive for COVID-19, continue to engage throughout their self-isolation to share best practices and provide timely, relevant updates that will help calm nerves and know what to do if symptoms escalate. While the initial interactions should be over the phone, you can automate educational material and updates. Remember, when using a messaging channel like SMS, you always need to make sure you obtain end user consent before sending messages.

Contact identification

Effective contact tracing relies on identifying the contacts that have been exposed to a patient recently, especially those who have been in close contact. If you didn’t receive a list of exposed contacts during the patient interview, follow-up via email or SMS (as long as you received the appropriate opt-in consent) with a link to a secure information portal for self-reporting contacts. Be sure to build in an escalation path to route patients to relevant and timely support if they have any issues.

Contact notification

Once you’ve identified the exposed contacts, decide who to manually call and who to send automated notifications based on exposure risk. Contact tracers should call highly exposed contacts. If they don’t pick up, leave a voicemail and follow-up via SMS if they opted in. SMS is a great follow-up option to constituents who have opted in because 90 percent of all text messages are read within 3 seconds.

Symptom tracking

Finally, whether it’s a patient or exposed contact, automate the 14-day symptom tracking process to monitor at scale. Provide directions to call public health authorities, a link to a symptom tracking survey, or implement an SMS chatbot for self-reporting.


How the regulatory compliance landscape affects contact tracing

It’s always mandatory to gain consent when messaging end users through channels like SMS. Now that you’ve identified the tasks you’re incorporating into your workflow, utilize the compliance guidelines to provide the proper opt-in and opt-out mechanisms for your community.

What happens when you want to automate notifications to exposed contacts who have not previously opted in? Are you at risk of legal ramifications? The short answer is a bit complicated.


On March 20, the Federal Communications Commission (FCC) issued a Declaratory Ruling stating that automated communications to the public with important COVID-19 information does not violate the Telephone Consumer Protection Act (TCPA).

This means, in certain circumstances, government entities do not need to worry about potential violations that could cost $500 to $1500 per unwanted message. There are two requirements to fall within this Declaratory Ruling:

  1. The messenger must be from a hospital, or be a healthcare provider, state or local health official, or other government official as well as a person under the express direction of such an organization and acting on its behalf; and

  2. The content of the message must be solely informational, made necessary because of the COVID-19 outbreak, and directly related to the imminent health or safety risk arising out of the COVID-19 outbreak.

But, what does it mean for content to be “directly related to the imminent health or safety risk arising out of the COVID-19 outbreak”? Here are some examples:

  1. A message from a hospital with vital and time-sensitive health and safety information that citizens welcome, expect, and rely upon to make decisions to slow the spread of the COVID-19 disease.

  2. An informational message to inform and update the public about measures to address the pandemic, made on behalf of, and at the express direction of, a healthcare provider.

  3. A message from a county official to inform citizens of shelter-in-place requirements, quarantines, medically administered testing information, or school closures necessitated to the national emergency.

So, does that mean you’re in the clear when it comes to SMS for contact tracing tasks? No. This is truly an exception for the COVID 19 pandemic. Further, the TCPA exemption does not replace proper consent/opt-in.


The CTIA (Cellular Telecommunications Industry Association) represents the U.S. wireless communications industry and companies throughout the mobile ecosystem. The association provides messaging principles and best practices to protect end users from unwanted messages. 

Why does this matter? Deliverability.

Especially during this time, carriers are working tirelessly to ensure critical information gets delivered while also protecting against spam and misinformation. They continually evaluate whether messages are wanted or not based on their guidelines. If messages are unwanted or fall outside other aspects of their guidelines, they will be blocked.

This is where opt-ins become really important.

The goal is to protect end users from spam while providing the information they need to stay informed and healthy. Failure to gain consent can erode trust, harm providers’ reputation, and ultimately impact organizations’ ability to send messages at all. When it comes to notifications to exposed individuals who haven’t previously opted in, there are a few things you can do to obtain consent:

  • Manually call and then ask the exposed contact to opt into SMS.

  • Email the contact and let them choose the channel they prefer to use.

  • Utilize billboards in your city or state asking citizens to opt into a specific number to be notified if they’ve been exposed to COVID-19.

  • Create a landing page on your website or add social media posts asking citizens to input their number to be notified if they’ve been exposed to COVID-19.

Remember, digital communications done the right way builds trust with your constituents. Outside of deliverability, these strategies help ensure citizens know the communication is coming from your trusted organization and not potential spammers.

Select the right number type for contact tracing notifications

As you set up your messaging strategy with contact tracing tasks and compliance in mind, the next step is selecting the right number type to deliver your messages. In the United States, this includes long codes, toll-free and high throughput toll-free, and short codes. With each number type, there are key considerations that impact your strategy.

Long Codes (Not recommended)

While long codes get you up-and-running fast with instant provisioning, they are limited to sending just one message per second, and are intended for person-to-person (P2P), not application-to-person (A2P) traffic. This means using long codes could invite heavy filtering by carriers who evaluate spam reports, content, velocity, and more to try to identify and filter traffic that isn’t consistent with P2P messaging. When running high volume contact notification tasks, it is likely that many of your critical messages will not reach exposed contacts.

Toll-free and High Throughput Toll-free (Recommended while waiting for short code or for non-critical messages)

Toll-free numbers, while part of the long code family, are specifically intended for A2P traffic. Like long codes, they can be instantly provisioned; however, unlike long codes, they can be sent at three messages per second. If you’re sending high volumes of messages, you can also request high throughput toll-free. The verification process takes several days, but provides a rate of 25 messages per second while also decreasing carrier filtering.

This process gives carriers the chance to understand the specific use case before messages are sent at scale, allowing them to confirm it’s traffic that’s beneficial to end users. Toll-free or high throughput toll-free numbers are great alternatives while waiting for a short code to be approved.

Short Codes (Recommended)

For high volume, critical messages short codes are, by far, the best option. They can be sent at 100+ messages per second and offer unparalleled deliverability. Before being able to use a short code, carriers require you complete an application proving you are within compliance guidelines. While the review process typically takes 8-12 weeks, carriers are working hard to expedite the process for COVID-specific uses.

Because carriers are able to review content, opt-in flows, and more, they do not filter short codes once they are approved. This means your messages are going to reach users with critical information at the right time.

Start simple, iterate quickly

Now that you have a foundation start simple with outbound support for tasks citizens have opted into, utilizing channels like SMS, email, and voice. While you might want to implement an OTT channel like WhatsApp, it’s not an option for government entities for outbound messages. However, you can onboard WhatsApp to respond to incoming messages about COVID-19.

As you evolve your strategy and add automated contact notification, configure basic two-way support, like handling a “Y” response for constituents to continue receiving communications.

Finally, consider incorporating intelligent two-way support into your workflow. Offload common questions or exchanges to an intelligent assistant, reserving contact tracers for more complex interactions. Incorporate channel escalations, using analytics and engagement to send an SMS if the citizen doesn’t open an email or answer a call.

Throughout this process, we are committed to helping you deliver critical messages to citizens at scale. See more in our COVID-19 Communications Field Guide, or explore support for building contact tracing programs.

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Chris Piwinski

Chris Piwinski

Chris Piwinski is a product marketing manager at Twilio where he works on programmable messaging. His focus is on how organizations can drive trust and engagement with their customers through channels like SMS, WhatsApp, and more. Prior to Twilio, Chris spent time in product marketing, sales, and project management at LinkedIn, Headspace, and a payments technology startup.

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