Children with immunodeficiency at higher risk of serious COVID-19: Study

London: Children with certain immunodeficiency diseases may have a higher mortality rate due to COVID-19, according to a study.

Researchers noted that most children infected with the SARS-CoV-2 develop a mild illness or show no symptoms at all, but for a small percentage, serious complications may develop.

The study, recently published in the Journal of Allergy and Clinical Immunology, found that children with certain immunodeficiency diseases carry mutations in genes that regulate the body's immune system against viral infections.

"Mortality is much higher among children with primary immunodeficiency diseases infected with SARS-CoV-2," said Qiang Pan-Hammarstrom, a professor at Karolinska Institutet in Sweden.

"Our results indicate that basic immunological examination and genetic analysis should be conducted in children with severe COVID-19 or multi-inflammatory syndrome (MIS-C). The clinicians will then be able to help these children with more precise therapies based on their genetic changes," said Pan-Hammarstrom.

Researchers performed genetic and immunological analyses in young patients with primary immunodeficiency diseases -- also called inborn errors of immunity -- who developed severe or critical SARS-CoV-2 infection.

"Our results clarify the molecular mechanism of these immune diseases, which opens up the possibility of developing a more targeted therapy," Pan-Hammarstrom said.

"The knowledge acquired from the study also allows us to develop better strategies for the treatment and prevention of severe COVID-19 disease in these patients," the scientist said.

The study included 31 children aged five months to 19 years. All children had some type of primary immunodeficiency disease without a molecular diagnosis and suffered from severe COVID-19.

Participants were recruited from August to September 2020 in Iran. None of them were vaccinated against COVID-19.

Eleven of the children, more than one-third, died of complications from the infection, the researchers said.

Five children, 16 per cent, met the criteria for multi–inflammatory syndrome, MIS-C. Some of the children lacked antibodies to the coronavirus, they said.

"This suggests that many children with this type of immune disease cannot produce antiviral antibodies and therefore would not have the full benefit of vaccination," said Hassan Abolhassani, assistant professor at Karolinska Institutet, and the study's first author.

Genetic analyses showed that more than 90 per cent of the participants, 28 children, had mutations in genes that are important for our immune defense, and that could explain their immunodeficiency, the researchers said.

An important mechanism was mutations that affect proteins which regulate the immune system during virus infection, known as interferons, they said.

The study also included a literature review, where the researchers globally found reports of about 1,210 patients with primary immunodeficiency disease and COVID-19. About 30 per cent of them were children.

The mortality rate among children with primary immunodeficiency disease and COVID-19 was more than 8 per cent, compared with about 0.01 per cent among children in the general population, they added.