# Privacy and Security in Digital Health Contact-Tracing: A Narrative Review
## 3 Results
### Technical Issues
#### 3.4.2 Technology Issues  
This includes the problems that arise from the use of technology, including both hardware and software issues. Initially, many participants found the app unusable, struggling with QR code scanning. People reported they had to install and uninstall the app multiple times until a version compatible with their phone was released [24]. Users emphasised that the elderly or individuals with older phones faced difficulties downloading the app and using it correctly [25]. The adoption of contact-tracing apps was also influenced by factors related to the phone, including issues with storage, version compatibility, and battery life. Phone-related issues represented actual or perceived technical difficulties relating to the contact-tracing app [101]. A frequently cited problem was the absence of smartphones compatible with the app [73]. This mainly happened in the earlier versions of the app. In a Belgian study, reasons cited for not installing the app included not having a smartphone (18.5%) or possessing an older smartphone model (9.4%) [66]. The potential adoption rates of contact-tracing apps were reduced to 81.3% and 81.8%, respectively, due to limitations in installing apps and handling Bluetooth functions in Germany [73]. Technical issues were also a significant factor, with almost 20% citing them as a reason in Italy [127]. It was also reported that functional (technical) complexity negatively influenced the intention to adopt contact-tracing apps in India [49]. Technical issues reported included the contact-tracing app not being user-friendly, the inability to download the app on older mobile devices, and older devices having limited space for apps [99]. Certain respondents mentioned that the age or model of their phones prevented them from downloading the app. Another prevalent barrier was the impact on phone batteries due to keeping Bluetooth switched on constantly, which led to quick depletion and made respondents less inclined to download or use the app [17; 103; 116]. In several studies, the reasons for not installing or stopping using the contact-tracing app were concerns about excessive battery usage and its impact on battery life, among other reasons [20; 23; 123]. Some users found contact-tracing apps to be less user-friendly and battery-draining, leading to their decision not to use the apps [119]. Problems during installation (4.6%), concerns about difficulties during installation (6.4%), and fear of battery drainage (9.7%) were less frequently chosen as other reasons for not installing the app [66]. In a study conducted in New Zealand, concerns mentioned by respondents included time consumption (17.2%), slow loading (7.3%), bugs and technical errors (7.3%), battery consumption (3.8%), and various technical reasons. Notably, around a third of respondents expressed satisfaction with the app, agreeing that it worked [84]. Battery drainage and the possibility of unwanted notifications were mentioned as negative user experiences limiting individuals' willingness to download the contact-tracing app [50]. The lack of an up-to-date phone (94%) was mentioned as a barrier in the USA [42]. This finding was supported by several studies, as reasons for app non-use included not having a suitable smartphone [23; 41] or operating system (22.8%) [23]. Similar findings have been reported in Canada; among participants, factors cited for not downloading the app included not having an appropriate smartphone and a lack of knowledge on how to download the contact-tracing app [18]. People were not willing to invest in a new smartphone, driven by frustration with the government's decision not to develop an app compatible with all mobile phones. This was one of the reasons for being unwilling to use a contact-tracing app in Wales [61]. Barriers to adopting contact-tracing apps include not having a smartphone and potential out-of-pocket costs [113].