Age, sex and seasonal differences in COVID-19 viral load: a Lebanese cross-sectional study

Coronavirus disease 2019 (COVID-19) is a respiratory infection caused by a virus known as severe acute respiratory syndrome coronavirus 2. It has resulted in more than 6 million deaths worldwide and continues to impact our daily lives. Diagnosis of the disease relies on determining the CT (Cycle Threshold) value through reverse transcription polymerase chain reaction with a higher CT-Value indicating a lower viral load. While COVID-19 has been studied in terms of pathophysiology, symptoms, and treatment, fewer large-scale studies have addressed how viral load varies by age, sex, and season. This study aims to illustrate if sex, age, and seasonal changes have an impact on the viral load of COVID-19 within an initial Lebanese cross-sectional study.

Data for our study was gathered from the Al-Hadi Medical Center since the onset of the pandemic. A total of 686,739 participants were included in our analysis. Age, sex, and seasonal variation were extracted from the available data. Individuals under the age of 1 were excluded from the study.

The predictors for a positive PCR were being a female, being a child or a senior, and testing during a cold and humid season. Children had a higher CT value compared to seniors. Linear regression showed that an increase of 1 year in age is mirrored by a decrease of 0.013 in CT value. Concerning sex, females have an average of 0.149 lower CT value than males. Finally, the CT value is higher by an average of 1.392 in cold and rainy seasons compared to hot and dry ones.

Sex, age, and seasonal variations are modest predictors of the viral load of COVID-19. All these demographic and seasonal factors may affect the viral load and should be taken into consideration when implementing infection control strategies and clinical management in SARS-CoV-2-positive patients.