The research suggests the immune system could be stronger in older age than previously thought.
Mosquito saliva may be increasing the severity of diseases.
Cancer experts expressed hope after learning that former President Jimmy Carter's melanoma would be treated with Merck & Co's Keytruda drug.
The tool is expected to help doctors find hard-to-detect infections in time to stop them in their tracks.
Chad Hayes on why he allowed his baby to be given all the shots.