Self-rated health when population health is challenged by the COVID-19 pandemic; a longitudinal study

RATIONALE: The coronavirus disease 2019 (COVID-19) pandemic and consequent lockdown measures have had a large impact on people's lives. Recent evidence suggests that self-rated health (SRH) scores remained relatively stable or increased during the pandemic. OBJECTIVE: For the current project, we examine potential changes in the variance decomposition of SRH before and during the COVID-19 pandemic in the Netherlands. METHODS: We analyse data from the Netherlands Twin Register to examine pre-pandemic SRH scores (N = 16,127), pandemic SRH scores (N = 17,451), and SRH difference scores (N = 7464). Additionally, we perform bivariate genetic analyses to estimate genetic and environmental variance components in pre-pandemic and pandemic SRH, and estimate the genetic correlation to assess potential gene-environment interaction. RESULTS: = 0.49, CI = 0.37 to 0.60). CONCLUSIONS: We theorize that the increases in SRH are explained by uninfected individuals evaluating their health more positively than under normal circumstances (partly through social comparison with infected individuals), rather than actual improvements. As the same genes are expressed under different environmental exposures, these results imply no evidence for gene-environment interaction. While different environmental factors might influence SRH at the two time-points, the influence of environmental factors does not become relatively more important during the pandemic.