I've installed over 1,000 apps from the Play Store, have also installed apps from numerous third party apps stores, and directly from apk files. As well as that, I've often got updates for installed apps (including things like Google Play services) from third party (usually Chinese) app stores instead of from the Play Store. Despite all of that, I've never got infected.
So while articles like the above one clearly indicate that there is a malware problem for Android devices, I've managed to stay completely malware free. The only things virus scanners have picked up are apps containing ads, and Avast once found a PUP which I had intentially installed.
My current phone, while still receving regular OTA updates, is stuck with a variant of Android 5.1, so cit ertainly does not have recent security patches, but I'm not too worried.
In my opinion if you get your apps only from the Play Store, then the chance of getting infected will be very small.