Residing with kids doesn’t enhance adults’ danger of extreme COVID-19, say researchers

Researchers working on behalf of NHS England have found no evidence that adults who live with school-age children are at any increased risk of severe outcomes following infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) – the agent that causes coronavirus disease 2019 (COVID-19).

The large population-based study was conducted by researchers from the London School of Hygiene and Tropical Medicine (LSHTSM), the University of Oxford and The Phoenix Partnership, to investigate the growing concern that children may serve as a major reservoir for the spread of SARS-CoV-2.

“This is the first population-based study to investigate whether the risk of recorded SARS-CoV-2 infection and severe outcomes from COVID-19 differ between adults living in households with and without school-aged children during the UK pandemic,” writes the team.

Among working-age adults (aged 65 years or younger), living with children aged 0 to 11 years was not associated with any increased risk for SARS-CoV-2 infection or COVID-19-related hospitalizations, compared with working-age adults who did not live with children.

Among this age group, living with children aged 12 to 18 years was associated with a slightly increased risk of infection, but not with COVID-19 outcomes. In addition, living with children of any age lowered the risk of deaths due to causes unrelated to COVID-19.

Among adults older than 65 years, no associations were identified between living with children and any outcomes related to SARS-CoV-2.

Laurie Tomlinson and colleagues say the findings have implications for determining the benefits versus harms of children attending school while the pandemic continues.

A pre-print version of the paper is available on the server medRxiv*, while the article undergoes peer review.

The role children play in transmission is unclear

Modeling studies of other respiratory tract infections have pointed to children as a major source of spread during the initial phase of an epidemic, partly due to their frequent engagement in social contacts.

However, a growing body of evidence suggests that in the case of SARS-CoV-2, children may be less susceptible, less infectious, and no more likely to transmit the virus than adults.

One suggested mechanism for a lower susceptibility among children is cross-reactive immunity to SARS-CoV-2, acquired through infection with seasonal human coronaviruses (hCoVs). These infections, which cause the common cold, are more frequent among children than among adults, with the highest infection rates observed among young children.

“If recent hCoV infection is protective against SARS-CoV-2 infection or COVID-19, then adults living with children may be at a lower risk than those living without children,” say Tomlinson and team.

On the other hand, children may introduce SARS-CoV-2 to into their households and adults living in close contact with children may be at an increased risk of infection, they add.

“In the face of increasing transmission in many countries and the need for policy decisions about school opening, quantifying the overall impact of living with children on the risk of SARS-CoV-2 infections and severe outcomes from COVID-19 is important,” write the researchers.

What did the team do?

Tomlinson and colleagues used UK electronic health records linked to data on household members to investigate whether the risk of SARS-CoV-2 infection and severe COVID-19 outcomes differed between adults who live with children and those who do not.

The study used primary care data and linked information on hospital and intensive care unit (ICU) admissions and death records from patients registered with general practices, representing 40% of England.

The team used multivariate Cox regression to calculate the risk of outcomes between February 1st and August 3rd, 2020, after adjusting for sex, age, index of multiple deprivations, body mass index, smoking status, ethnicity, and number of adults in the household.

The final cohort included 9,157,814 working-age adults (65 years and younger) and 2,567,671 adults aged over 65 years.

What did the researchers find?

Among working-age adults, sharing a house with children aged 0 to 11 years was not associated with any increased risk for recorded SARS-CoV-2 infection or COVID-19-related hospital or ICU admission. However, the team did observe a 25% reduced risk of COVID-19-related death.

Among the same age group, living with children aged 12 to 18 years was associated with an 8% increased risk of recorded SARS-CoV-2 infection, but not any increased risk of other COVID-19 outcomes. Living with children of any age was also associated with a reduced risk of death from causes unrelated to COVID-19.

Among adults older than 65 years, there was no evidence of an association between living with children and any outcomes related to SARS-CoV-2, irrespective of the children’s age group.

In all analyses, additional adjustment for comorbidities did not significantly change the results and no consistent differences in risk of infection or severe outcomes were observed on comparing periods before and after school closures.

The findings have important implications

“Our results demonstrate no evidence of serious harms from COVID-19 to adults in close contact with children, compared to those living in households without children,” write the researchers.

“These findings, in consideration alongside other evidence, have implications for determining the benefit-harm balance of children attending school in the COVID-19 pandemic,” concludes the team.

*Important Notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

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