However, results from a study demonstrated that during the COVID-19 outbreak from 2020 to 2021, maintaining good hygiene reduced the risk of infection, which could account for the declines in IgG levels in both adults and children, but IgE levels did not change from the pre-COVID-19 which was before 2019 to the COVID-19 period [16]. The gene discussed is IGHE; the disease is infection.