Hygienic behaviors during the COVID-19 pandemic may decrease immunoglobulin G levels: Implications for Kawasaki...

Area of Science:

• Immunology
• Epidemiology
• Public Health

Background:

• The COVID-19 pandemic led to widespread adoption of enhanced hygienic behaviors.
• The hygiene hypothesis suggests that reduced exposure to microbes may negatively impact immune system development and function.
• This study investigates the impact of pandemic-related hygiene measures on immunological parameters.

Purpose of the Study:

• To quantify the effect of COVID-19 on immunological parameters, specifically immunoglobulin G (IgG) and IgE levels.
• To examine age-specific changes in IgG and IgE in relation to the hygiene hypothesis during the pandemic.

Main Methods:

• Retrospective analysis of age-specific total nonspecific immunoglobulin G (IgG) and IgE levels.
• Data collected from individuals visiting Fukuoka Tokushukai Hospital between 2010 and 2021.
• Comparison of immunological parameters between the pre-COVID (2010-2019) and COVID (2020-2021) periods.

Main Results:

• Immunoglobulin G (IgG) levels showed a steady decline pre-COVID and an abrupt decrease during the COVID period across all age groups.
• The decline in IgG levels accelerated in neonates (< 0.3 years) and older individuals (≥ 5 years) during the COVID period.
• Immunoglobulin E (IgE) levels exhibited seasonal variations but no significant change between the pre-COVID and COVID periods. Patients with Kawasaki disease (KD) had significantly lower IgG levels compared to controls.

Conclusions:

• Increased hygienic practices during the COVID-19 pandemic are associated with decreased IgG levels in all age groups, from neonates to adults.
• The observed reduction in IgG may compromise immune defenses, potentially increasing vulnerability to infections and Kawasaki disease (KD).
• Further research is needed to understand the long-term implications of reduced IgG levels on immune health.