Just like Covid19, some can carry the virus without noticing any effects , others die.
Perhaps you have a robust immunity system honed by your exposure to countless shared Eucharists and you will be fine.
Of course during your decades of life it is pretty probable that you have been exposed to most diseases going around your neighborhood whatever you have noticed them or not and gained some measure of immunity not even counting normal vaccinations that most people get on industrialized societies.
If you should happen to get introduced to a whole host of new diseases and germs at the same time......well it would be bad.
Guns Germs & Steel: Variables. Smallpox | PBS
“Within just a few generations, the continents of the Americas were virtually emptied of their native inhabitants – some academics estimate that approximately 20 million people may have died in the years following the European invasion – up to 95% of the population of the Americas.
No medieval force, no matter how bloodthirsty, could have achieved such enormous levels of genocide. Instead, Europeans were aided by a deadly secret weapon they weren't even aware they were carrying:
Smallpox.“
Pretty sordid stuff. Informative link though. Gives bit of scope how bad it could get.
Millions of natives dying to diseases they had no immunity for nor time or knowledge to handle while under European conquest of their lands.