Measles infection can greatly reduce acquired immune memory, according to a new study. Acquired immune memory is when a person's immune system attacks foreign invaders and can remember how to fight the dangerous antigens in the future. "Measles virus infects immune cells, particularly long-term immune memory cells, causing immune "'amnesia'" which can last for varying amounts of time," says Dr. Gregory Poland, director of the Mayo Clinic Vaccine Research Group.

"This laboratory-based study demonstrates the depth and severity of what has been observed clinically for some time, namely, that after measles infection, but not measles vaccine, the ability of the immune system to respond to other pathogens is significantly diminished, leading to increased risks and complications from other infections," says Dr. Poland. "This study is a further important step in understanding the underlying scientific basis for the long-lasting harm that measles virus infection can cause."

Immune memory

"Immune memory develops after we are exposed and infected with various pathogens, allowing the body to "'remember'" what it has previously been exposed to and allowing very rapid production of protective immune responses after reexposure," says Dr. Poland. "Measles virus infection significantly harms the body's ability to maintain that immune memory and rapid response."

Study significance

"The significance of this is that measles infection harms the body's ability to recognize, remember and fight off other infections besides measles virus. This leads to an enhanced risk of infection with other viruses and bacterial, and an increased risk of complications," says Dr. Poland. "These findings reinforce the importance of vaccination."

Measles symptoms and complications

Measles is a highly contagious viral infection that spreads through coughing or sneezing. Complications may include ear infection, pneumonia and encephalitis, which can result in permanent brain damage. In the US, 3 of 1,000 people infected with measles will die. In developing countries, 1 of 100 people will die from complications of the virus.

Measles can be prevented with the measles, mumps and rubella (MMR) vaccine. The Centers for Disease Control and Prevention recommends that MMR be given to children at 12–15 months of age. A second dose is recommended before a child starts school, around ages 4–6. If children receive an early dose of MMR vaccine between 6 and 11 months of age because of international travel or a local outbreak, they still will require both routine doses after 1 year of age for full protection.