Tanel Tera, head of e-services at the Health and Welfare Information Systems Center (TEHIK) said it was not possible to find out how many notifications have been sent to close contacts.
"The application collects local contact data on the phone and it is not transmitted to the servers associated with the application," he said.
"HOIA" was created in voluntary cooperation between the Ministry of Social Affairs (Sotsiaalministeerium), the Health and Welfare Information Systems Center (Tervise ja Heaolu Infosüsteemide Keskus) and 12 Estonian companies - Cybernetica, Fujitsu Estonia, Guardtime, Icefire, Iglu, Mobi Lab, Mooncascade, Velvet, FOB Solutions, Heisi IT OÜ, Bytelogics and ASA Quality Services OÜ.
The purpose of the app is to inform close contacts of those infected with the coronavirus and to provide them with instructions on how to proceed. Its aim is to limit the spread of coronavirus.
It works because phones which use the app register Bluetooth signals from other nearby phones. If the signal is sufficiently close and long enough, an anonymous code referring to a close contact will be stored in their phone.
It is not possible to identify a person based on an anonymous code.
Priit Tohver, Ministry of Social Affairs adviser in the field of e-services and innovation told ERR News in August: "The more people that use it [HOIA], the more effective it will be."
HOIA was launched on August 20.
Editor: Helen Wright