This idea is based on the assumption that adherence to Sharia will bring one success and prosperity in this world as well as the next. That also leads to jihad activity, since jihad warfare against unbelievers is likewise a Sharia tenet.
“Muslims ‘immune to coronavirus’ some imams in Somalia say, putting public at risk,” by Emily Judd, Al Arabiya, May 10, 2020 (thanks to The Religion of Peace):
Some imams in Somalia are saying Muslims are immune to COVID-19, going against senior Muslim scholars who have insisted the coronavirus pandemic is a severe threat to all people around the globe.