Malnutrition hampers the proper functioning of the immune system and is known to increase the risk of severe infections for other viruses, but the potential long-term effects of malnutrition on Covid-19 outcomes are less clear, said Louis Ehwerhemuepha from Children's Hospital of Orange County in California, US.

Children older than five and adults aged 18 to 78 years with previous diagnoses of malnutrition were found to have higher odds of severe Covid-19 than those with no history of malnutrition in the same age groups.

Children younger than five and adults aged 79 or above were found to have higher odds of severe Covid-19 if they were not malnourished compared to those of the same age who were malnourished. In children, this may be due to having less medical data for those under five, according to the researchers.

The risk of severe Covid-19 in adults with and without malnutrition continued to rise with age above 79 years. The findings are published in the journal Scientific Reports.

Malnutrition, as a global health problem for both the pediatric and adult population, will continue to overlap with the Covid-19 pandemic that has already affected millions worldwide, Ehwerhemuepha said.

The researchers suggest that public health interventions for those at highest risk of malnutrition may help mitigate the higher likelihood of severe Covid-19 in this group.

For the study, the team investigated associations between malnutrition diagnoses and subsequent Covid-19 severity, using medical records for 8,604 children and 94,495 adults (older than 18 years) who were hospitalised with Covid-19 in the US between March and June 2020. Patients with a diagnosis of malnutrition between 2015 and 2019 were compared to patients without.

Of 520 (6 per cent) children with severe Covid-19, 39 (7.5 per cent) had a previous diagnosis of malnutrition, compared to 125 (1.5 per cent) of 7,959 (98.45 per cent) children with mild Covid-19. Of 11,423 (11 per cent) adults with severe Covid-19, 453 (4 per cent) had a previous diagnosis of malnutrition, compared to 1,557 (1.8 per cent) of 81,515 (98.13 per cent) adults with mild Covid-19.