METHODOLOGY: Patients' socio-demographic and epidemiological data, clinical features, laboratory findings and clinical outcomes were extracted using a data sheet.
RESULTS: The median patient age was 25 [interquartile range (IQR)] 20-44) years, and most of patients were male (68.7%) and of Malaysian nationality (88.4%). Almost half of the patients were from a case cluster related to a religious event (48.3%) and 12.9% had a history of overseas travel. A total of 33.3% of patients were not related to any case cluster, i.e. sporadic cases. Radiological investigation showed that 13.6% of the patients had chest X-ray changes and all laboratory parameters were within the normal ranges. Sixty-six patients (44.9%) experienced symptoms. The most common symptoms were rhinitis (66.7%), followed by fever (19.7%) and cough (15.2%). Age, gender, case cluster, comorbidity status, haemoglobin, albumin, total protein, bilirubin total and alkaline phosphatase level were associated with symptomatic status.
CONCLUSIONS: In this single-centre study, COVID-19 infection led not only to case clusters, but also to sporadic infections, with patients being either symptomatic or asymptomatic. These sporadic cases and asymptomatic patients may hamper effective contact tracing, leading to rapid human-to-human transmission in our population. Future studies on the prevalence and clinical significance of asymptomatic and presymptomatic COVID-19 patients would pre-emptively address issues on further containment of the pandemic.
MATERIALS AND METHODS: A retrospective cross-sectional study was conducted among healthcare workers who received the COVID-19 vaccine during the first phase of immunisation from eight public primary clinics in Johor Bahru district. Data were collected between May and September 2021 using a self-administered questionnaire.
RESULTS: A total of 240 healthcare workers participated and all of them received the Pfizer Messenger RNA vaccine. Our study found that a large majority of vaccine recipients (87.5%, n=210) experienced AEFI to COVID-19 vaccine for either the first, second, or both doses. More than 80% of them experienced more than one type of AEFI. The most common AEFI reported during the first and second dose was localised symptom such as pain at injection site (60-68%), pain on the injected arm (52-61%), and swelling at injection site (32-33%). Common systemic symptoms were fever (22- 57%), myalgia (20-45%), and dizziness (24-26%). Although a large majority experienced AEFI, these reactions were mostly of mild to moderate severity (47.3-73.6%). The mean duration of AEFI onset was within 30 minutes to about 1 day (0.33-22.5 hours) of injection and lasted between 30 minutes and 2.5 days. There was no association between demographic characteristic of participants and severity of AEFI to COVID-19 vaccine. Mean duration of fever was significantly (p=0.005) longer after the second dose (34.2 hours) of vaccine compared to first (20.6 hours) CONCLUSION: This study shows that a large majority of COVID-19 vaccine recipients experienced AEFI; however, these reactions were mostly of mild to moderate severity and lasted between 30 minutes and 2.5 days. A large majority experienced more than one type of AEFI. The most common AEFI was localised reactions consisting of pain and swelling at the injection site and pain on the injected arm. The most common systemic reactions were fever, myalgia, and dizziness. Duration of fever was significantly longer after the second dose.