Figure 1.

Box plots showing the increasing mortality trend by increasing HAV susceptibility in the 213 countries affected by the virus. If the data is limited to countries with more than 1 million population, 5 million population and 5000 tests/1 million population, the associated risk with increasing HAV susceptibility is even stronger (Supplementary file). The analyses do not take into account several confounding factors that may affect the death rates, including, but not limited to, socioeconomic status, accessibility of health services, and government pandemic policies. For example, Australia, New Zealand, Singapore, Japan, and South Korea are countries with excellent policies against the COVID-19 pandemic and have low mortality rates in the high susceptibility group. In contrast, countries with serious socioeconomic problems, such as Ecuador and Peru, have high mortality rates in the low susceptibility group. These are examples of a possible bias towards the null, while it is accepted that other sources of bias away from the null may exist.