Background: Close contact with children may provide cross-reactive immunity to SARs-CoV-2 due to more frequent prior coryzal infections from seasonal coronaviruses. Alternatively, close contact with children may increase risk of SARs-CoV-2 infection. We investigated whether risk of infection with SARs-CoV-2 and severe outcomes differed between adults living with and without children.
Methods: Working on behalf of NHS England, we conducted a population-based cohort study using primary care data and pseudonymously-linked hospital and intensive care admissions, and death records, from patients registered in general practices representing 40% of England. Using multivariable Cox regression, we calculated fully-adjusted hazard ratios (HR) of outcomes from 1st February-3rd August 2020 comparing adults living with and without children in the household.
Findings: Among 9,157,814 adults ≤65 years, living with children 0-11 years was not associated with increased risks of recorded SARS-CoV-2 infection, COVID-19 related hospital or ICU admission but was associated with reduced risk of COVID-19 death (HR 0.75, 95%CI 0.62-0.92). Living with children aged 12-18 years was associated with a small increased risk of recorded SARS-CoV-2 infection (HR 1.08, 95%CI 1.03-1.13), but not associated with other COVID-19 outcomes. Living with children of any age was also associated with lower risk of dying from non-COVID-19 causes. Among 2,567,671 adults >65 years there was no association between living with children and outcomes related to SARS-CoV-2. We observed no consistent changes in risk following school closure.
Interpretation: For adults living with children there is no evidence of an increased risk of severe COVID-19 outcomes. These findings have implications for determining the benefit-harm balance of children attending school in the COVID-19 pandemic.
Funding: This work was supported by the Medical Research Council MR/V015737/1
Read the full paper on medRxiv here.
Living with children not linked with greater risk of severe coronavirus in adults, during the first wave of the UK coronavirus pandemic
There are two competing hypotheses about whether close contact with children can change the risk of severe COVID-19. On the one hand, it has been suggested that children may confer some cross-reactive immunity to SARs-CoV-2, due to their passing on ‘colds’ from other seasonal coronaviruses more frequently. Alternatively, it has been suggested that children may pass SARs-CoV-2 infection on to their close contacts.
To investigate these hypotheses, researchers at LSHTM and Oxford University used the OpenSAFELY data platform to run analyses securely across the full pseudonymised health records of 12 million adults, comparing the COVID-19 risks in those living with and without children. The researchers were able to take into account many potentially influential factors including smoking, socioeconomic deprivation, ethnicity, geographic area, and chronic health problems. This is an observational study based on routinely collected health records.
Adults under 65 living with children aged up to 11 years did not have increased risks of recorded infection with SARS-CoV-2, COVID-19 related hospital or intensive care unit (ICU) admission. They were about 25% less likely to die of COVID-19 than people living without children; however, importantly, they were also similarly less likely to die of non-COVID-19 causes during the study period (32% lower risk). People with children aged 12-18 years had a small (8%) increased risk of recorded SARS-CoV-2 infection but no increased risk of hospitalisation, ICU admission or death from COVID-19. They were also, again, less likely to die of non-COVID-19 causes during the study period. For adults aged over 65 years there was no difference in risk of recorded SARS-CoV-2 infection or COVID-19 related outcomes for people living with or without children of any age.
At the beginning of the study period, schools were fully open, then after March 20th they were closed except to key-workers’ and vulnerable children, and later were completely closed for the summer holidays. The researchers examined whether the risks among adults living with children differed, when comparing the periods before and after April 3rd (3 weeks after school closure). They found no consistent differences in risk of the outcomes between adults living with and without children before and after April 3rd.
This is an observational study of real individuals’ health records. One limitation of the study is the testing data: results in the GP record were used to identify whether patients were recorded as having SARS-CoV-2 infection. However these tests were not done at random in the general population, and in the early period of the study were more likely to be given, for example, to people in high-risk jobs where testing was more easily available. Overall these findings may, alongside other evidence, help policymakers determine the best trade-off between the benefits and harms of closing schools during the COVID-19 pandemic.