What is 'Immune Amnesia'?

As well as triggering symptoms like a rash, fever and inflamed eyes, new research from Harvard University suggests that measles also wipes the immune system’s memory and leaves the body vulnerable to other viruses and diseases it may have previously been capable of fighting off.

Michael Mina, an infectious disease epidemiologist and pathologist at Harvard T.H. Chan School of Public Health refers to the phenomenon as “immune amnesia” and warns that by erasing the immune system’s memory of past infections, the measles virus can have a much longer and more dangerous impact on the human body. In some cases, he says the aftermath can last for months or even years.

“It really puts you at increased susceptibility for everything else,” he warns, referring to other viruses and bacteria linked to diarrhea, pneumonia and ear infections.

Unravelling the viral cycle

The measles virus works by initially targeting immune cells present in mucus found in the nose and throat. It also attacks immune cells between the eyelids and cornea, as well as in the lungs. The virus rapidly duplicates inside the cells, then spreads to other areas of the body that are rich in immune cells, including bone marrow, lymph nodes, tonsils, spleen and thymus. This severe loss of immune cells means that during infection, victims can be left more vulnerable to other infections. In addition to the symptoms associated with measles, Mina and his team also warn that the virus depletes memory immune cells and hinders the body's ability to fight off future infections.

The theory was tested on a group of unimmunised Dutch children, with blood samples taken from 77 healthy children. More samples were gathered following an outbreak of measles, with the team noting that after a measles infection the immune system lost a significant number of 'memory cells' that are used to fight off previously contracted infections.

New findings challenge anti-vaccination movement

The findings were reported in Nature Communications and come in the wake of new figures revealing the scope of the anti-vaccination movement. In the UK, Unicef warns that around half a million children are at risk of contracting measles after missing vaccinations. For Mina and other health experts, the new findings could help reinforce the importance of vaccinating children and help promote the broader "safety halo" that comes with the measles vaccine.

“Wherever you introduce measles vaccination, you always reduce childhood mortality. Always,” asserts Rik de Swart, a virologist at Erasmus University Medical Center in the Netherlands.

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