Climate & BCG: Effects on COVID-19 Death Growth Rates

TL;DR

This study investigates how climate, BCG vaccination, pollution, and blood type influence COVID-19 death growth rates across 40 regions, finding limited evidence for climate factors and no significant link to BCG or pollution, but a strong correlation with positive test rates.

Contribution

It provides a joint analysis using machine learning and Bayesian methods to evaluate multiple factors affecting COVID-19 death growth rates, highlighting the significance of positive test rates.

Findings

Weak evidence for climate factors like temperature and humidity

No significant link between BCG vaccination and death growth

Positive test rate strongly correlates with death growth

Abstract

Multiple studies have suggested the spread of COVID-19 is affected by factors such as climate, BCG vaccinations, pollution and blood type. We perform a joint study of these factors using the death growth rates of 40 regions worldwide with both machine learning and Bayesian methods. We find weak, non-significant (< 3$\sigma$) evidence for temperature and relative humidity as factors in the spread of COVID-19 but little or no evidence for BCG vaccination prevalence or $\text{PM}_{2.5}$ pollution. The only variable detected at a statistically significant level (>3$\sigma$) is the rate of positive COVID-19 tests, with higher positive rates correlating with higher daily growth of deaths.