Role of Weather Factors in COVID-19 Deaths in Tropical Climate: A Data-Driven Study Focused on Brazil Manuscript

Abstract

Background: Brazil reported 123,780 deaths across 27 administrative regions, making it the second-worst affected country after the US in terms of COVID-19 deaths as of 3 September 2020. Understanding the role of weather factors in COVID-19 in Brazil is helpful in the long-term mitigation strategy of COVID-19 in other tropical countries because Brazil experienced early large-scale outbreak among tropical countries. Recent COVID-19 studies indicate that relevant weather factors such as temperature, humidity, UV Index (UVI), precipitation, ozone, pollution and cloud cover may influence the spread of COVID-19. Yet, the magnitude and direction of those associations remain inconclusive. Furthermore, there is only limited research exploring the impact of these weather factors in a tropical country like Brazil. In this observational study, we outline the roles of 7 relevant weather factors including temperature, humidity, UVI, precipitation, ozone, pollution (visibility) and cloud cover in COVID-19 deaths in Brazil. Methods: We use a log-linear fixed-effects model to a panel dataset of 27 administrative regions in Brazil across 182 days (n=3882) and analyze the role of relevant weather factors by using daily cumulative COVID-19 deaths in Brazil as the dependent variable. We carry out robustness checks using case-fatality-rate (CFR) as the dependent variable. Findings: We control for all time-fixed and various time-varying region-specific factors confounding factors. We observe a significant negative association of COVID-19 daily deaths growth rate in Brazil with weather factors - UVI, temperature, ozone and cloud cover. Specifically, a unit increase in UVI, maximum temperature, and ozone independently associate with 6.0 percentage points [p<0.001], 1.8 percentage points [p<0.01] and 0.3 percentage points [p<0. 1] decline in COVID-19 deaths growth rate. Further, a unit percentage increase in cloud cover associates with a decline of 0.148 percentage points [p<0.05] in COVID-19 deaths growth rate. Surprisingly, contrary to other studies, we do not find evidence of any association between COVID-19 daily deaths growth rate and humidity, visibility and precipitation. We find our results to be consistent even when we use the CFR as the dependent variable. Interpretation: We find independent protective roles of UVI, temperature, ozone and cloud cover in mitigating COVID-19 deaths, even in a tropical country like Brazil. We observe these results to be consistent across various model specifications, especially for UVI and cloud cover, even after incorporating additional time-varying weather parameters such as dewpoint, pressure, wind speed and wind gust. These results could guide health-related policy decision making in Brazil as well as similar tropical countries.

The impact of vaccination on the spread patterns of the COVID epidemic

“…The most notable changes in the growth rate of COVID19 are related to the effects of the UV index and air temperature. For example, in [10], an increase in UVI decreases the maximum infection rate by about 6% per unit increase in the index. Other studies have cited a wide range of values for the effect of temperature.…”

“…For that purpose, model calculations were made of the relationship between i max and vaccination rate. The value of i max was calculated using dependence (10), assuming that = . The maximum vaccination time was estimated based on the condition that no further spread of the epidemic is possible with a vaccination rate of around 80% ,i.e.…”

“…The calculation was carried out according to (15), but instead of t v the time of change in lockdown conditions t L. was substituted in this equation. The values of the number of infected persons i0 and I L for selected times t L at λ = 0.035 1/day were calculated using equation (10). When the timing of the lockdown change and the start of vaccination coincide, i.e.…”

“…The calculation is carried out first by ( 4) or ( 6) and then, for the time period during which the vaccination takes place, by (10).…”

Does Climate Play Any Role in COVID-19 Spreading?—An Australian Perspective

“…Studies conducted across many regions suggest links between climate factors and COVID-19 transmission and mortality and, dependent on the variable, either a direct or inverse relationship [4,6,7]. For example, Takagi et al [8] observed that temperature, exposure time to solar radiation, and ultraviolet index (UVI) are negatively related to COVID-19 transmission, whereas wind speed and increasing sky cover are positively related.…”