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.

The outbreak of COVID-19 has affected the world with over two million cases globally. Malaysia has witnessed over 5,000 with almost 100 deaths as of 22 April 2020. Knowledge on the incubation period of COVID-19 is scarce due to the novelty of the virus. The aim of this study was to determine the incubation period of COVID-19 infection in the district of Petaling in Malaysia. A cross-sectional study was conducted using secondary data from the Petaling District Health Office. We analysed data of laboratory-confirmed COVID-19 cases notified to the Petaling District Health Office between 3 February 2020 and 13 April 2020. Our study included 219 cases. The median incubation period of COVID-19 among the cases was five days (interquartile range 3.0-8.0). Four main clusters were identified, with significant difference found between two of the clusters. Cluster A has a shorter incubation period 3.5 (3.0-6.8) compared to cluster B as most of the confirmed cases knew the source of infection. COVID-19 incubation period in Petaling, Malaysia fits within the range estimated by the World Health Organization. Based on the upper value of the incubation period interquartile range in our study, the length of quarantine and period of contact tracing should be at least 8 days. This finding is in accordance with our current practice to control the spread of COVID-19