A child just under two years old was very sick in January of 2021. His doctors couldn't figure it out. He was having convulsions. Meningitis was thought to be the cause, as well as a Tuberculosis diagnosis. The child was transferred to the largest hospital in the country for further evaluation.

The child's doctors were not able to figure out why he wasn't getting better. They reached out to Trine Mogensen, a professor of immunology at the University of Aarhus. There was no evidence of a disease. She says that the child's genome was sequenced to see if there were any clues.

They found a change in the gene that codes for IFNAR2 that causes it to bind to type I interferons. Interferons play an important role in fighting off viral infections. Without type I interferons working well, the child wouldn't be able to mount an immune response to Viruses such as Covid-19 and the flu.

The child was facing a mystery virus. Christopher Duncan is a clinician-scientist who studies viral immunity and interferons at the University of the United Kingdom. Duncan had been researching the same genetic abnormality for several years, first documenting it in a paper in the journal Science Translational Medicine. He and his colleagues found a genetic variant in a family from Ireland. A 13-month-old infant had a severe case of encephalitis after receiving the vaccine that protects against the measles, mumps, and rubella viruses. The child's illness was fatal.

Duncan and his colleagues were contacted by researchers in Alaska who had identified a couple of children who had run into major problems with multiple Viruses and had the same genetic variant. Two children in northern Canada had the same condition.

Mogensen and Duncan went back to the child from Greenland to find the root of his condition. Three weeks before he fell ill, they discovered he had also been shot with the live vaccine. The child is now healthy. In April, Duncan and Mogensen published their findings in the Journal of Experimental Medicine.

The team wanted to know if there were more people carrying this genetic abnormality. They noted that the boy from Greenland and the children from Alaska were all descendants of the Inuit. It was found that 1 in 1,500 people in the Inuit population were carrying the variant.