A COVID-19 software endorsed by Queen Elizabeth's granddaughter Zara Tindall and her husband Mike Tindall has reportedly been referred to regulators because of some safety concerns over its advertisement.

Zara, an Olympic equestrian, and Mike, a former rugby superstar, appear in the ad to demonstrate how VHealth Passport works. They explain in the video that the process is a "game-changer" because it can help appease the worries of those in the sports industry who need to travel for matches and other public events.

Allegedly, the passport may serve as proof that athletes are safe to participate in the games. Sports fans may also use the app if they want to watch the games live.

The equestrian is also shown in the video taking an antibody test. She uploads her results on her phone app.

However, the BBC reported that an antibody test doesn't show if a person is actively carrying the virus, per the U.K. government's guidance. The antibody test is different from a swab test, which shows if a person currently has the virus.

Biostatistics professor Jon Deeks of the University of Birmingham told BBC that if people only relied on the VHealth Passport and get a negative antibody result, then they might think that they cannot be infectious. As a result, they might stop observing safety protocols like social distancing or wearing a face mask.

But VST Enterprise, which owns VHealth Passport, said that the test Zara took was for "illustrative purpose," which may also help screen individuals for "possible current infection." Zara and Mike allegedly made it clear in the ad that they were taking a rapid antibody test for three different antibodies.

The VHealth Passport was first referred to the Medicines and Healthcare products Regulatory Agency (MHRA), which concluded that its software should not be treated as a medical device for diagnosing COVID-19. The agency said that this matter must be investigated by the Advertising Standards Authority (ASA) further.

VST Enterprises confirmed that it is in touch and engaged with the regulators. A spokesperson for the company, however, said that the BBC report relies on just one expert comment from Deeks.

The company also clarified that it is not selling coronavirus tests. Rather, its product is an app that provides a way for individuals to book a test at a medical facility that follows the government's guidance.

Zara and Mike Tindall or their spokesperson have not commented on the issue, as of press time.