Children more vulnerable to virus than thought, study shows

A study by KU Leuven and Sciensano has shown that children are more likely to be infected with Covid-19 than first thought – though they rarely become ill from the virus.

Investigators followed 362 children in 10 primary and secondary schools in Alken and Pelt, in Limburg. During the first wave of the pandemic, Alken was one of the worst-affected areas in the country, while Pelt suffered only a small number of infections. The aim was to identify whether this difference between the two municipalities was also apparent among children.

Blood and saliva samples were taken from the children to test for antibodies – indicating a previous infection with Covid-19 – and their parents filled in a questionnaire that indicated possible risk contacts, health and social behaviour. In Alken, antibodies were found in 14.4% of children (26 out of 181), compared to 4.4% in Pelt (eight out of 181). The study showed little difference between infections in primary and secondary education.

“In studies of blood samples in clinical labs, and in health workers and blood donors, the number of people with antibodies is usually less than 10%,” said Els Duysburgh, a researcher at Sciensano. “These studies may therefore underestimate the real circulation of the coronavirus.”

Researchers believe the children with antibodies were infected during the first wave, just before or after the lockdown, based on the evolution in the number of infections in each municipality between March and October, and the answers from parents about contact with infected people.

“At the time of the infection, lots of measures that we are now so familiar with – handwashing, maintaining distance, wearing masks – were not yet adopted by everyone, particularly children,” said professor Corinne Vandermeulen of KU Leuven, who led the research. “That may help explain why we found antibodies in a relatively high number of children.”

However, the study showed that children rarely became sick from the virus. The 34 who developed antibodies suffered very few symptoms.

“These infections mainly took place from adults within the family. Schools do not seem to have played a significant role in the spread of the virus in the first wave,” said Vandermeulen. However, she emphasised the study was not intended to investigate the transfer of the virus within schools or the role of children in transmitting the virus.

The current autumn school holidays were extended by a week, with children due to return to class on Monday. The head of Ghent’s university hospital, Dominique Benoit, told VRT he believes the return to school is happening too soon and he fears a third wave of the virus.

Photo: Belga/Thierry Roge