Epi Info Companion is a free iOS application that allows users to collect, analyze, and manage data on their mobile devices. Developed by the Centers for Disease Control and Prevention, this app is designed to work in conjunction with Epi Info 7 software on desktop PCs. The app offers several features for data entry, including the ability to import collection forms via email, enter new records, recall and update existing records, and package and encrypt local datasets.

In addition to data entry, Epi Info Companion also offers data analysis tools such as frequency analysis, 2x2 or MxN tables with associated statistics, and means with associated statistics. The app also includes StatCalc statistical calculators, which have been adapted for iOS and allow users to input data using the iPad's touchscreen interface.

Lastly, the VHF Contact Tracing feature allows users to load a dataset of contacts of Viral Hemorrhagic Fever cases, select records from that dataset, enter follow-up information for a record, transmit the follow-up information to a master database via SMS, and save the follow-up information to the local data table.

Overall, Epi Info Companion is an excellent tool for those who need to collect, analyze, and manage data on-the-go.