Objective: Various public health and social measures have been used during the COVID-19 outbreak, including lockdowns, contact-tracing, isolation and quarantine. The objective of this manuscript is to describe outbreaks of COVID-19 in Selangor, Malaysia, the public health strategies used and the observed impact of the measures on the epidemic curve. Methods: Information on all confirmed COVID-19 cases in Selangor between 25 January and 28 April 2020 was obtained. Clusters were identified, and cases were disaggregated into linked, unlinked and imported cases. Epidemic curves were constructed, and the timing of movement control orders was compared with the numbers of cases reported. Results: During the study period, 1395 confirmed COVID-19 cases were reported to the Selangor Health Department, of which 15.8% were imported, 79.5% were linked and 4.7% were unlinked cases. For two main clusters, the number of cases decreased after control measures were instituted, by contact-tracing followed by isolation and home quarantine for the first cluster (n = 126), and with the addition of the movement control order for the second, much larger cluster (n = 559). Discussion: The findings suggest that appropriate, timely public health interventions and movement control measures have a synergistic effect on controlling COVID-19 outbreaks.

Introduction: Measles outbreaks are endemic in Southeast Asia. A possible reason for such outbreaks is low vaccine coverage. In Malaysia, there is a lack of studies on measles outbreaks. The urban district of Petaling in Selangor, Peninsular Malaysia, reported a high number of outbreaks in 2014–2018. Thus, we analysed the trend of measles outbreaks and identify the common characteristics of measles cases in Petaling District. Methods: This was a cross-sectional study using secondary data from the Petaling District Health Office online surveillance system. Data from 2014 until 2018 from the e-Measles and eWabak systems were extracted, and the trend and common characteristics of measles cases were analysed. Results: A total of 48 outbreaks involving 124 cases were reported during the period investigated. The outbreaks showed an increasing trend from 2.1% in 2014 to 37.5% in 2016, and decreased slightly from 29.2% in 2017 to 27.1% in 2018. The common characteristics were age 1 to <7 years (50.8%), female sex (55.6%), Malay ethnicity (89.5%), Malaysian citizenship (95.2%) and being unvaccinated (55.6%). Of the cases, 63.7% were admitted to hospital, and siblings were the common source of infection (75.8%). Most cases occurred at home (75.8%). Most of the children who were infected at home were unvaccinated (60.6%). Conclusion: Unvaccinated children aged 1 to <7 years are at highest risk of contracting measles and spreading it to their siblings. Thus, awareness of the importance of vaccination needs to be emphasized to their parents to prevent related issues such as vaccine hesitancy.

Background: COVID-19 was first detected in Malaysia on 25 January 2020. Multiple clusters were detected in Petaling District, with the first locally transmitted case reported on 8 February. Descriptive analyses of the epidemiology of the COVID-19 outbreak in Petaling are presented, from the first case to the end of the first wave. Methods: All laboratory-confirmed COVID-19 cases reported to the Petaling District Health Office between 1 February and 26 June 2020 were analysed. Socio-demographic characteristics, symptoms, date of onset, date of exposure, travel history and history of comorbidities were obtained by phone interviews using one of two investigation forms. The descriptive analysis was conducted according to time, place and person. Results: There were 437 COVID-19 cases, for an incidence rate of 24/100 000 population. Ten (2.3%) deaths and 427 recovered cases were recorded. Of the 437 cases, 35.5% remained asymptomatic and 64.5% were symptomatic. Common symptoms included fever (43.8%), cough (31.6%) and sore throat (16.2%); 67.3% had no comorbidities, 62.5% reported close contact with a confirmed case, and 76.7% were local infections. Transmission occurred in four main groups: religious gatherings (20.4%), corporations (15.1%), health facilities (10.3%) and a wholesale wet market (6.4%). In 31.9% of confirmed cases, an epidemiological link to an asymptomatic case was found. Conclusion: Transmission of the disease by asymptomatic cases should be emphasized to ensure continuous wearing of face masks, hand hygiene and social distancing. Further research should be conducted to better understand the transmission of SARS-CoV-2 from asymptomatic cases.

Inntroduction: The rapid spread of the Coronavirus disease 2019 (COVID-19) worldwide has led the World Health Organization to declare COVID-19 outbreak as a pandemic on March 11, 2020. As the local studies on factors leading to the absence or presence of clinical illness among the COVID-19 cases are sparse, the study aims to determine the factors associated with asymptomatic COVID19 patients in Petaling District, Selangor, Malaysia Methods: Data on COVID-19 patients were extracted from the database of confirmed cases in Petaling District Health Office, Selangor, Malaysia from 3rd February 2020 to 30th April 2020. An asymptomatic laboratory-confirmed case is a person infected with COVID-19 who does not develop any symptoms. The study included socio-demographic variables, the detailed information on clinical manifestations and co-morbidity of the patients. Descriptive and multiple logistic regression analyses were conducted to determine the factors associated with asymptomatic patients. Results: The overall COVID-19 patients in Petaling District were 434. Approximately 70% (n= 292) of the patients were symptomatic while 32.7% (n= 142) were asymptomatic. Multivple logistic regression analyses revealed that factors significantly associated with asymptomatic patients were age below 40 years old (aOR: 1.79, 95% CI 1.11, 2.86), non-Malaysians (aOR: 3.22, 95% CI 1.44, 7.19) and local cases (aOR: 2.51, 95% CI 1.42, 4.42). Gender, ethnicity, comorbidity and township were not significantly associated with asymptomatic patients. Conlcusion Approximately one-third of COVID-19 patients were asymptomatic and the risk factors identified were younger age, non-Malaysians and local cases. Rigorous epidemiological investigation is helpful in identifying COVID-19 cases among these group of people who are asymptomatic.