Not really. Highly contagious viruses like smallpox could still travel on the entire Earth pretty easily, I mean yeah ok it takes weeks instead of days, but in the end it doesn't change anything once it's there, you're just delaying the inevitable. I believe almost all civilizations had the flu or similar virus, as long as they did any commerce with any other society. Our hygiene and quality of life is magnitudes higher than any other point in human history, that alone has been the real savior.