With the shift to AppleCare+, Genius Bar staff will no longer have the option of offering free replacements, so customers who have been aware of Apple's informal replacement policy should be mindful of the change.
Prevention of TB involves both early treatment to reduce transmission and isolation of the infected person until they are no longer contagious. There is a vaccine against TB, but it is not used routinely in the U.S. because of efficacy issues and other problems.
You can help prevent nasal congestion due to cold and flu viruses by practicing good hygiene. Wash your hands frequently, avoid sharing drinking glasses or utensils, use alcohol-based hand sanitizers and avoid close contact with people who are sick.