New Delhi: Children who test positive for Covid-19 can spread the infection to at least half of the household contacts if Covid-appropriate behaviour is not followed at homes, a new study has found.
The study, published in the New England Journal of Medicine on 2 September, was conducted on students who attended an overnight camp in Georgia in 2019, which resulted in a coronavirus outbreak.
Titled ‘Household Transmission of SARS-CoV-2 from Children and Adolescents’, the study was conducted in collaboration with the Center for Disease Control and the Georgia Department of Public Health in Atlanta.
“This retrospective study showed that the efficient transmission of SARS-CoV-2 from school-age children and adolescents to household members led to the hospitalization of adults with secondary cases of Covid-19. In households in which transmission occurred, half the household contacts were infected,” the study said.
A retrospective study is where “investigators go back in time to identify a group that was initially unexposed and study the incidence of their exposure”.
What the study found
Researchers interviewed 224 children between the ages of 7-19 for whom there was evidence of SARS-CoV-2 infection on the basis of molecular or antigen laboratory testing.
A total of 198 of these campers (88 per cent) were symptomatic. Among them, symptoms developed in 141 children or adolescents (71 per cent) after they returned home from the camp.
Of 526 household contacts of these index patients, 377 (72 per cent) were tested for SARS-CoV-2. Of these, 46 (12 per cent) tested positive. Two cases of secondary infection were also found in these households. A secondary infection means that a person gets an infection unrelated to the first problem they had. In this case, it means someone with Covid-19 gets infected with another illness.
The median interval between the onset of symptoms in the index patient (child) and the onset of symptoms in the household contacts infected by that patient was found to be five days.
The researchers found that in 35 of 195 households, the virus spread from the child to the family. In about 48 percent of the households, the infection spread to vulnerable or susceptible members. Of all these infected members, 10 per cent of them had to be hospitalised for treatment and other members who had secondary infections were above the age of 18 years.
The study found restricted spread in households where distance was maintained and preventive measures were taken.
It said, “In a multivariable regression model, the risk of a secondary case of infection among household contacts was lower among contacts of index patients who had practiced physical distancing than among contacts of index patients who did not. Household members who had close or direct contact with the index patient had a higher risk of infection than those who had minimal to no contact.”