Introduction: Infant hepatitis B vaccination was introduced into the Expanded Programme on Immunisation (EPI) in Malaysia in 1989. This study aimed to investigate seroprevalence of hepatitis B among UKM pre-clinical medical students, born between 1991 and 1995, and had their infant vaccination more than 20 years ago. Materials and Methods: A prospective, cross-sectional study involving 352 students, comprising 109 (31.0%) males and 243 (69.0%) females. Blood specimens were tested for anti-HBs, where levels of ≥10 mIU/mL was considered reactive and protective. Students with non-reactive levels were given a 20 µg HBV vaccine booster. Anti-HBs levels were tested six weeks after the first booster dose. Those with anti-HBs <10 mIU/mL were then given another two booster doses, at least one month apart. Anti-HBs levels were tested six weeks after the third dose. Results: Ninety-seven students (27.6%) had anti-HBs ranging from 10 to >1000 mIU/ mL while 255 (72.4%) had anti-HBs <10 mIU/mL. After one booster dose, 208 (59.1%) mounted anti-HBs ≥10 mIU/mL. Among the remaining 47 (13.3%), all except two students (0.6%) responded following completion of three vaccination doses. They were negative for HBsAg and anti-HBcore antibody, thus regarded as non-responders. Conclusions: Anti-HBs levels waned after 20 years post-vaccination, where more than 70% were within non-reactive levels. For healthcare workers, a booster dose followed by documenting anti-HBs levels of ≥10 mIU/mL may be recommended, to guide the management of post-exposure prophylaxis. Pre-booster anti-HBs testing may not be indicated. Serological surveillance is important in long-term assessment of HBV vaccination programs. No HBV carrier was detected.
serological surveillance ; healthcare workers

Prior to COVID-19, dengue was an important public health problem in Malaysia. Due to the movement control order imposed by the Malaysian government to curb the COVID-19 transmission, a study predicted that mosquito-borne diseases would increase during lockdown and partial lockdown seasons. Thus, this study aims to determine the current situation of dengue incidence during the pre-COVID-19 pandemic (2019) and during the COVID-19 pandemic (2020 and 2021). We compared the number of laboratory-confirmed cases in the pre-COVID19 year (2019) and during the COVID-19 pandemic (2020 and 2021). In addition to that, we characterized the clinical manifestation, dengue serotype and viremia levels of dengue patients that were admitted to the Hospital Cancelor Tuanku Muhriz. We found a significant decrease in the number of laboratory-confirmed cases between COVID-19 pandemic and the pre-covid period (p2020=0.064; p2021<0.001). In this study, we found DENV 4 serotype was the most common serotype in dengue patients admitted to our hospital. There was no significant correlation between DENV serotype/viremia level with clinical manifestation of dengue fever and dengue with warning signs. However, patients infected with DENV4 had the highest viral load compared to patients infected with other serotypes. We also found high viremia levels were significantly associated with the febrile phase.