EXTRATERRESTRIAL IMMUNE SYSTEMS ARE DEADLY!

If you ever encounter an Alien Being , you Adrenaline will pump through your veins lik crazy so you will either do one of two things, One you might run away screaming for help or Two!, you might decide to Attack it or Grab it!.

The Worst thing you can ever do in your whole Life is to touch an Alien Being, their Immune Systems are Deadly to Humans and part of the reason for this is because they have Bacteria that is foreign to a Human Immune System. Space Bacteria something which your Immune System isn't acustomed to will literrally destroy your Immune System and Kill you within hours. Even your Germs can be deadly to them Also that is why it is very important you never , ever touch an Alien Being even the Human Types because they too carry foreign Germs that will kill you!, so be warned.
When the Dark Government sends their Special Task Forces to Recover Alien Space Crafts and the Aliens they are suited with Bio-suits , Radiation Sensor Equiptment and Weapons just in case, this Recovery Operation is swift and deadly any witnesses that happen to be there at the wrong place and wrong time are Terminated and properly dsposed of, No Witnesses is their Policy, then they Send or bury the Space Crafts depending on the Size of the Spacecraft and the Arrests of the Entities to be sent to Interrogation Centers and Vivisection Labs.

This is Serious Business and their is no room for error, this Operation is Dead Serious and Heavily Compartmentalized so the Incidents never get out to the Public.
Here is a Brazillian Report on an Alien Capture by the Brazillian Military listen to the Report carefully , this Report made it to the Public Wow!.

https://www.youtube.com/watch?v=sOhOYHXcPaY

Is immune system for all extra-terrestrials deadly for humans?

They Vary because if these Beings come from another Planet the Bacteria has evolved in a different World altogether meaning that the germs are foreign and this means your Immune System will just shut down and the person would die, some Planets probably have similar germs and other planets would have very foreign germs.