Here are a few basic ones to lay down fundamentals . Plenty out there Have fun!
https://www.coursera.org/specializations/immunology
https://www.coursera.org/learn/sars-cov2-and-acute-respiratory-viral-infections
https://www.coursera.org/learn/methods-of-molecular-biology
https://www.coursera.org/learn/epidemics?
https://www.coursera.org/learn/wgs-bacteria
https://www.coursera.org/learn/epidemiology
https://www.coursera.org/lecture/covid-19/intro-to-the-virology-of-covid-19-bjsa5
https://www.coursera.org/learn/covid-19-genome-assembly