You are obviously ignorant of true Allien Medical Research cappasity! Their Viruses are so advanced that they would only damage, but not kill, the right handed paddy whackers, who also belived in or who voted for Democrats-Leftist-Scocialist-Liboral Polititions! It would also cause the left handed amoung them to become right handed and then infect them too, just to be fair! The damage would be to their brains only and cause them towant to become usefull pleasure toys or industrial slaves! The rest of us are much to valuable just as we are to be harmed in any way and then the Alliens would then wellcome us into their society as new consumers and producers who would help raise the standard of living for all concerned!

We would have NO chance.It would be a total defeat and genocide. They could lob asteriods at us from space. Launch EMP attacks that would send us back to the stone age.Robot attacks, you name it. However we wouldn't even get a chance to see much less kill an alien.After all would we send soilders if we had robots.  Maybe ,if they let us live, in a couple of centeries we could adapt their technology and fight back but even then it would be a pipe dream