# Impact of temperature and humidity on SARS-CoV-2 transmissibility: a systematic review and meta-analysis

## TL;DR

This study finds that higher temperature and humidity are linked to lower transmission of SARS-CoV-2, suggesting climate factors can help predict and manage outbreaks.

## Contribution

The study provides a systematic review and meta-analysis of temperature and humidity effects on SARS-CoV-2 transmissibility using R for statistical analysis.

## Key findings

- Temperature increase reduces SARS-CoV-2 transmissibility by 0.008 per degree Celsius.
- Humidity increase reduces transmissibility by 0.006 per percentage point.
- Both temperature and humidity show significant negative correlations with virus spread.

## Abstract

The SARS-CoV-2 pandemic remains crucial for understanding the epidemiology of future respiratory infections. Gaining insights into the climatic factors influencing the transmissibility of SARS-CoV-2 is an important public health issue in the control and prevention of the disease. Hence, this study aimed to assess the association between SARS-CoV-2 transmissibility and both humidity and temperature.

Articles published between December 2019 and August 2024 were identified from PubMed, Africa Journal Online, Science Direct, and Hinari databases following PRISMA guidelines. The focus was on studies that reported transmissibility based on basic reproductive number, specifically correlation coefficients between basic reproductive number and temperature, or humidity, or corresponding regression coefficients, and their standard errors. The Joanna Briggs Institute (JBI) Critical Appraisal Checklist was used to assess the risk of bias. Random effect models were applied. The meta-analysis was done in R version 4.3.0.

9 studies qualified, but 5 were excluded for missing coefficients, leaving 4 for meta-analysis. The study analysis revealed a significant negative correlation between temperature and SARS-CoV-2 transmissibility (r = −0.509, 95% CI: −0.680 to −0.338, p < 0.001). Similarly, a significant but weaker negative correlation was found between humidity and SARS-CoV-2 transmissibility (r = −0.426, 95% CI: −0.548 to −0.303, p < 0.001). A unit increase in humidity measured in percentage was associated with a decrease in transmissibility by 0.006 (95% CI: −0.007 to −0.004, p < 0.001), while a unit increase in temperature in Celsius (°C) was associated with a reduction of transmissibility by 0.008 (95% CI: −0.030 to −0.030, p < 0.001).

Temperature and humidity were negatively associated with SARS-CoV-2 transmissibility; thus, disease transmissibility decreased as temperature or humidity increased. Climatic factors are important considerations for effective disease surveillance and preparedness strategies.

https://www.crd.york.ac.uk/PROSPERO, CRD42025637440.