Clinical Manifestations and Progression of Varicella among Adults at Siriraj Hospital, Thailand: A Prospective Cohort Study

Varicella is a highly contagious viral disease that is very common in children. Adults are less likely to acquire varicella; however, therate of its complication is higher. There are few published data on varicella among adults in Thailand. This study aimed to demonstrate the clinical manifestations, progression and environmental factors of varicella in adults. From January 2018 to June 2022, a prospective cohort study was conducted among adult patients diagnosed with varicella visiting Siriraj Hospital. Demographic data, history of varicella and varicella vaccination, onset, types of lesions, and distribution were recorded. Participants were followed until the varicella was completely cured. During the study, the average temperature of each month was recorded. Fifty patients were included inthe study. Interestingly, varicella was diagnosedin patients with a history of varicella infection (18%) or varicella vaccination (14%), especially in healthcare providers. Generalized vesicles were the most common manifestation. From the univariate or multivariate analysis, the duration of the curewas shown to be significantly shorter among those who had a history of vaccination by approximately 3 days (p=0.007). The duration of cure was not significantly associated with age, sex, receiving treatment within 48 hours after the initial lesions, or having a history of previousvaricella. Interestingly, the number of varicella patients per month was found to be significantly lower in months with an average temperature greaterthan 30 degrees Celsius (p<0.0001). Our findings demonstrated that varicella reinfection occurs in Thai adults and in those with a history of vaccination. Adults who had been vaccinated had a significantly shorter duration of the disease. Therefore, varicella vaccination is recommended, particularly among healthcare professionals who may have contact with varicella patients.