Research published in the BMJ today sheds light on the risk of infection with SARS-CoV-2 and COVID-19 outcomes among adults living with and without children during the first two waves of the UK pandemic.
Led by the London School of Hygiene & Tropical Medicine (LSHTM) and the University of Oxford, the study finds no evidence of any increased risk in the first wave of the pandemic. Small increased risks of infection and hospital admission were seen in the second wave, but this did not translate into a materially increased risk of COVID-19 mortality.
The role of children and adolescents in the transmission of SARS-CoV-2 is still uncertain. Some evidence suggests they are less susceptible to infection because they catch more colds from seasonal coronaviruses each year than adults.
Adults living with children also have more “common colds” than do those not living with children and this could result in a lower risk of serious outcomes from SARS-CoV-2 infection. Alternatively, living with children may lead to greater opportunities for infection with SARS-CoV-2 and increased risks to adults they live with.
To address this uncertainty, the researcher team investigated whether the risk of infection and serious outcomes from COVID-19 differed between adults living with and without school-age children during the first two waves of the UK pandemic.
They drew on primary care data from the OpenSAFELY analytics platform for 12 million adults aged 18 years and over linked to hospital and intensive care admissions and death records in England during wave 1 (1 February to 31 August 2020) and wave 2 (1 September to 19 December 2020). Presence and age of children in each household was recorded, and factors known to be associated with severe COVID-19, such as age, sex, ethnicity, weight (BMI), and underlying health conditions were taken into account.
The researchers then analysed the data to see who developed SARS-CoV-2 infection, was admitted to hospital or intensive care, or died from COVID-19. Outcomes for adults aged 18-65 years, and older adults (over 65 years) were analysed separately.
Study lead author, Dr Harriet Forbes from the Faculty of Epidemiology and Population Health, LSHTM, said: ‘During the first wave of the pandemic in England, for adults living with children there was no evidence of an increased risk of COVID-19 outcomes. However, in the second wave, we observed a small increased risk of COVID-19 infection and hospital admission, but no materially increased risk of COVID-19 related death.’
Study co-author Dr Ben Goldacre, Director of the DataLab at Oxford University’s Nuffield Department of Primary Care Health Sciences, said: ‘Our study shows the power of NHS data. We were able to run complex statistical models, securely, across an unprecedented scale of pseudonymised patients' records, without ever exposing or moving any patient data outside of the secure environment where it already resides. This proves that we can preserve patients' privacy while delivering urgent public health research.’
Co-author Dr Laurie Tomlinson, Faculty of Epidemiology and Population Health, LSHTM, said: ‘Our study shows the overall impact of living with children on the risk of a range of outcomes as a result of Coronavirus during the first and second waves of the pandemic, compared to similar households without children. Although increased risks were small they demonstrate the importance of continued adherence to social distancing regulations and of monitoring the impact of schools reopening on rates of coronavirus.’
Absolute increases in risks were small – researchers estimated the number of people recorded to have a SARS-CoV-2 infection rose from 810 to between 850-870 per 10,000 people living with children aged 0-11 years and to between 970-1000 for those living with children aged 12-18 years over the period of wave 2.
For hospital admissions with COVID-19, living with children aged 0-11 was associated with an increase from 160 to between 161-165 per 10,000 people years and for those living with children aged 12-18 years to between 162-166.
There was no increase in risk of death in either wave. People living with children of any age were less likely to die of non-COVID causes overall, and people living with children aged 0-11 years were also less likely to die of COVID-19 in the first and second waves.
This was a large, well-designed study using electronic health record data, and results were largely unchanged after further analyses, suggesting that they withstand scrutiny. However, the findings are observational and the authors did not rule out the possibility that other unmeasured factors or missing data may have affected the results.
The authors acknowledge limitations of the study, including that the findings are observational and the authors cannot rule out the possibility that other unmeasured factors or missing data may have affected the results.
They note that the increased risks during wave 2 were seen at a time when schools remained open, raising the possibility that widespread school attendance may have led to increased risks to households, but other differences between households with and without children could also have explained these findings.
The study was funded by the Medical Research Council. The researchers were working on behalf of NHS England and in partnership with NHSX.