A basic understanding of Covid-19 is a pre-requisite to understanding COVID-19 Infection control. John Hopkins University has prepared excellent public learning modules that will give you the background you need for this training. Their training consists of four short course modules before starting this training. All four modules can be completed in less than one hour, including watching the videos, reviewing the key takeaways and completing the knowledge tests (not graded).
If you need a refresher for any of the modules, they are found here:
Introduction to Diagnosing, Treating, and Preventing COVID-19
Medical Therapies and Vaccines in Development
Epidemiology: Understanding the Spread of COVID-19