A Decrease in Temperature and Humidity Precedes Human Rhinovirus Infections in a Cold Climate.

Area of Science:

• Environmental Health
• Virology
• Epidemiology

Background:

• Human rhinovirus (HRV) infections are a significant cause of respiratory illness.
• Environmental factors like temperature and humidity are suspected to influence HRV transmission and host susceptibility.
• Understanding these relationships is crucial for public health interventions, especially in diverse climatic regions.

Purpose of the Study:

• To investigate the association between short-term variations in ambient temperature and absolute humidity (AH) and the risk of HRV infections.
• To determine if changes or levels of temperature and humidity are more critical in a subarctic climate.
• To provide evidence for targeted prevention strategies in cold regions.

Main Methods:

• A case-crossover study design was employed.
• Participants included 892 conscripts reporting respiratory symptoms during military training.
• 147 HRV cases were confirmed using real-time PCR, with exposure assessed in the three days preceding symptom onset.

Main Results:

• A decrease in daily ambient temperature and absolute humidity (AH) preceding HRV infection onset was associated with increased risk.
• An 8% increased risk of HRV infection per 1°C decrease in average temperature was observed.
• A 13-20% increased risk of HRV infection per 0.5 g/m³ decrease in AH was noted.

Conclusions:

• Short-term decreases in temperature and AH, rather than persistently low levels, are significant risk factors for HRV infections in cold climates.
• These findings highlight the importance of considering rapid environmental changes in HRV transmission dynamics.
• The results are applicable for developing personal protection and prevention measures in cold-residing populations.