The following are frequently asked questions about the RADx® MARS program and HL7v2.

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Why was RADx MARS established?

The National Institute of Biomedical Imaging and Bioengineering (NIBIB) established RADx MARS to promote a standards-based approach to reporting COVID-19 self-test results and to establish best practices for future reporting of remote diagnostics.

How much does it cost to participate in RADx MARS?

Reporting systems have a choice of sending test results to one of two hubs: (1) AHPL AIMS+ or (2) ReportStream. In either scenario, the cost to the reporting system for onboarding and test result transmission to state and federal systems is $0. To participate in the RADx MARS program, the reporting system must send messages that conform to a standard HL7v2 specification.

For how long will NIBIB fund APHL for the MARS program? What will happen when NIBIB stops funding APHL?

NIBIB can fund APHL for up to 3 years, per a contract that was awarded in March 2022. This will allow adequate time for ReportStream to grow its connectivity to state health systems and for reporting systems to make educated decisions in choosing a hub as the home diagnostics and reporting landscape evolves. Use of the RADx MARS HL7v2 specification will facilitate interoperability of the reporting messages between different hubs. 

Is the standard HL7v2 specification developed for this program consistent with FDA and other federal/state reporting requirements?

Yes, the HL7v2 specification was built to allow communication of data required at both state and federal levels, and is consistent with FDA, CDC, and HHS requirements. The specification was also designed to be accepted by all states and territories. Whether or not a message is sent to a particular state depends on that state's preferences for OTC reporting.  The reporting systems need only to send a single HL7v2 message per test result to the hub. The hub sends messages to states that desire it. The hub also de-identifies the messages and sends them to the federal health system, HHS Protect.

Does RADx MARS support FHIR?

Not at this time. Reporting specifications have been built using HL7v2 to support interoperability with state health systems. Working with ONC and the HL7 community, the program is building a FHIR specification that is moving through a balloting process. The hubs do not support FHIR messaging at this time but are expected to do so in the future. 

Does RADx MARS have requirements around mobile application design?

Yes, RADx MARS has adopted state and federal guidelines about what information apps should collect from users who agree to report their test results. Apps should enable users to report anonymously or opt to out of reporting altogether.


RADx MARS staff will work with reporting systems to review app front end design as part of the onboarding process. We emphasize the importance of a good UI/UX, in order to make reporting easy for users. Any changes made to an app may need to be reviewed by the FDA.

Who is responsible for keeping track of what states accept OTC test results?

The hubs are responsible for keeping track of state preferences. Reporting systems may report all available results to the hub. The hub will relay the test results to states based on state preferences. 

Is county FIPS used for routing to jurisdictions?

No, the county FIPS code is not used to determine routing to a jurisdiction. This is typically done by zip code or by state code, depending on the hub. 

Should end-to-end testing be completed prior to app approval request submission to the FDA?

This depends on the guidance from your organization's regulatory officers/team, however, it has been the experience with other OTC test manufacturers that they did not have to wait until end-to-end testing was complete prior to submitting their app for FDA approval


What should be used if patient phone number is unknown or is not a U.S. phone number?

If PID 13.6 (Patient phone area code) and PID 13.7 (Patient phone) are unknown or a non-US phone number, use '1' in place of the numbers. 111^1111111 

How many messages can be included in a single batch HL7 file?

The upper limit for single batch HL7 files (for the AIMS Hub) is 9,999 messages.

We have patient email address but not phone number. How do I complete PID-13.3 and the remaining fields in PID-13?

If email address is known and phone number unknown, please use INTERNET for PID 13.3. If phone number known and email address unknown, use PH for PID 13.3. If both are known, use the repeating characture. It should look like: ~ ^^PH^^^222^2222222~^^Internet^

Do any fields have a character limit?

Yes, some state and local public health jurisdiction systems cannot ingest an OBX-17.1 (Device Identifier) that is greater than 20 characters. If Device Identifier information is greater than 20 characters, use the NTE segment to repeat the Device Information in full.

Where does the NTE segment go in the message?

The NTE segment should come immediately after the OBX segment. 

How are OBX sets created?

OBX sets are created by entering a sequential digit in brackets immediate after OBX (e.g., OBX[2]). The use of the digit is not standardized to any given Ask-on-Order-Entry (AOE), so they should be used as needed. For example, if there are two AOEs that need to be reported, then use OBX[2] for one and OBX[3] for the next. OBX[1] is always reserved for the test result information.

Are time zones required if a timestamp is to be included in the message?

Yes, time zones are required. If time zone is unknown, please use <+0000>.