# Evaluating the impact of childhood BMI on the risk of coronavirus disease 2019: A Mendelian randomization study

## TL;DR

This study finds that childhood obesity may cause increased risk of severe COVID-19 outcomes like hospitalization and disease severity.

## Contribution

The paper provides causal evidence linking childhood obesity to higher risk of severe COVID-19 using Mendelian randomization.

## Key findings

- Childhood obesity increases the risk of hospitalization by 30% and severity by 38% for COVID-19.
- The causal association was consistent across multiple Mendelian randomization approaches.
- Childhood obesity promotes susceptibility to COVID-19, though this was not validated in all methods.

## Abstract

Although the correlation between childhood obesity and coronavirus disease 2019 (COVID-19) has been explored, the causality of these remains uncertain. Thus, we conducted a two-sample Mendelian randomization (MR) analysis to identify the causal association.

Instrumental variables of childhood obesity were selected from genome-wide association study involving 61,111 Europeans. Besides, we collected summary statistics of different COVID-19 outcomes (susceptibility, hospitalization, and severity) from genome-wide association study including more than 2 million Europeans. The inverse-variance weighted was applied to assess the causality of childhood obesity with COVID-19. Furthermore, we replicated the above association based on another study.

Inverse-variance weighted results suggested that childhood obesity promoted the COVID-19 susceptibility but has not been validated in other approaches. For hospitalization and severity of COVID-19, we found that childhood obesity, respectively, increased 30 and 38% risk (P < 0.001), which were consistent in other MR approaches.

Our study provides evidence for a causal relationship between childhood BMI and COVID-19 which is consistent with previous studies. Though these explanations are biologically plausible, further studies are warranted to elucidate the role of these.

Our study suggests the potential causal associations of childhood obesity with COVID-19, especially hospitalization and severity of COVID-19.