Abstract
The 2019-Coronavirus (COVID-19) pandemic has had a global impact. The effect of environmental temperature on transmissibility and fatality rate of COVID-19 and protective efficacy of Bacillus Calmette-Guérin (BCG) vaccination towards COVID-19 remains ambiguous. Therefore, we explored the global impact of environmental temperature and neonatal BCG vaccination coverage on transmissibility and fatality rate of COVID-19. The COVID-19 data for reported cases, deaths and global temperature were collected from 31st December 2020 to 3rd April 2020 for 67 countries. Temperature data were split into quartiles for all three categories (minimum temperature, maximum temperature and mean temperature). The impact of three types of temperature data and policy of BCG vaccination on COVID-19 infection was determined by applying the multivariable two-level negative binomial regression analysis keeping daily new cases and daily mortality as outcome. The highest number of cases fell in the temperature categories as following: mean temperature in the second quartile (6°C to 10.5°C), median 26, interquartile range (IQR) 237; minimum temperature in the first quartile (-26°C to 1°C), median 23, IQR 173; maximum temperature in the second quartile (10°C to 16°C), median 27.5, IQR 219. For the minimum temperature category, 28% statistically significant lower incidence was noted for new cases from the countries falling in the second quartile (2°C to 6°C) compared with countries falling in the first quartile (-26°C to 1°C) (incidence rate ratio [IRR] 0.72, 95% confidence interval [CI] 0.57 to 0.93). However, no statistically significant difference in incidence rate was observed for mean temperature categories in comparison to the first quartile. Countries with BCG vaccination policy had 58% less mortality as compared with countries without BCG coverage (IRR 0.42; 95% CI 0.18 to 0.95). Our exploratory study provides evidence that high temperature might not be associated with low transmissibility and countries having neonatal BCG vaccination policy had a low fatality rate of COVID-19.
Highlights
In December 2019, a cluster of cases with complaints of pneumonia and respiratory illnesses were reported in Wuhan, China [1]
As of 3rd April 2020, United States of America (USA) reported 2,45,540 confirmed COVID-19 cases followed by Italy (1,15,242), Spain (1,10,238), China (82,465) and Germany (73,522)
The most casualties related to COVID-19 were reported in Italy 13,917 (12.07%) followed by Spain 10,003 (9.07%) and USA 6,053 (2.47%)
Summary
In December 2019, a cluster of cases with complaints of pneumonia and respiratory illnesses were reported in Wuhan, China [1]. The novel SARS-CoV-2 originates from a large family of Coronaviridae nested under the sub-family of Ortho coronaviruses belonging to the beta-coronavirus attribute that primarily infects mammals and birds [6,7,8] It is a positive single-strand RNA coronavirus having a genome of approximately 30kb length which encodes for ten genes, four of which give rise to structural proteins such as spike (S), envelope (E), membrane (M) and nucleocapsid (N) [7, 9,10,11]. The transmissibility of COVID-19 is found to be higher (R0: 2–2.5) than both SARS-CoV (R0: 1.7–1.9) and MERS-CoV (R0:
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
