Sains Malaysiana 51(5)(2022): 1599-1608

http://doi.org/10.17576/jsm-2022-5105-27

Insights into Variations in COVID-19 Infections in Malaysia

(Pandangan tentang Variasi dalam Jangkitan COVID-19 di Malaysia)

KIRUBHA A/P SANMUGAN & MUZALWANA ABDUL TALIB^*

Department of Economics and Applied Statistics, Faculty of Business and Economics, Universiti Malaya, 50603 Kuala Lumpur, Federal Territory, Malaysia

Diserahkan: 28 Julai 2021/Diterima: 21 Mac 2022

Abstract

The present study aims to visualize the variations in the number of confirmed daily COVID-19 infections during the third wave in Malaysia through the application of control charts. This study also attempts to propose the target number of daily new cases that would bring the pandemic situation in Malaysia under control by utilizing the confirmed daily cases in Malaysia starting from 8^th September 2020 until 30^th June 2021. A modified Shewhart control chart was adopted to monitor the variations before and after the commencement of National Immunisation Programme (NIP). The chart shows a declining trend in the number of cases after the rollout of NIP whereby several days were brought to a state of statistical-in-control. But in less than three months after NIP commencement, there were huge variations in COVID-19 cases leading to drastic increase in the mean number of cases. These signal the presence of unnatural or assignable causes of variations which could be attributed to failure of curbing the risks of transmission, existence of various variants in the community, easing of containment measures and less adherence to the COVID-19 Standard Operating Procedures (SOPs). Significant shifts in the mean values prompt the development of a 3-phase modified Shewhart control chart. From the 3-phase chart, a series of daily number new cases that can be set as the target value to bring the pandemic situation in Malaysia under control, while flattening the epidemiological curve in the very near term.

Keywords: Control charts; COVID-19; variation study

ABSTRAK

Kajian ini bertujuan untuk menggambarkan variasi dalam jumlah jangkitan COVID-19 harian yang disahkan semasa gelombang ketiga pandemik ini di Malaysia melalui penggunaan carta kawalan. Dengan menggunakan kes harian bermula 8 September 2020 sehingga 30 Jun 2021, kajian juga cuba mencadangkan sasaran bilangan kes baru harian yang mungkin dapat membawa kepada keadaan pandemik yang lebih terkawal di Malaysia. Kajian ini mengadaptasi carta kawalan Shewhart yang diubah suai untuk memantau variasi bilangan kes sebelum dan selepas bermulanya Program Imunisasi Kebangsaan (NIP). Carta dihasilkan menunjukkan trend penurunan bilangan kes selepas pelancaran NIP dengan beberapa hari telah dikesan berada pada keadaan statistik-dalam-kawalan. Pun begitu, dalam masa kurang daripada tiga bulan selepas NIP dilancarkan, didapati terdapat variasi yang besar dalam kes COVID-19 yang menyebabkan peningkatan drastik dalam purata bilangan kes. Ini memberi isyarat hadirnya punca variasi luar biasa yang boleh dikaitkan dengan kegagalan membendung risiko penularan, kewujudan pelbagai varian baru dalam komuniti, pelonggaran langkah membendung serta kurangnya pematuhan kepada Prosedur Operasi Piawai (SOP) COVID-19. Anjakan ketara dalam nilai purata telah mendorong kepada pembangunan carta kawalan Shewhart ubah suai 3 fasa. Hasil daripada carta ini digunakan untuk membuat beberapa saranan mengenai bilangan kes baru harian yang boleh dijadikan sebagai sasaran dalam usaha membawa keadaan pandemik di Malaysia yang lebih terkawal, di samping usaha melandaikan lengkungan epidemiologi untuk tempoh terdekat ini.

Kata kunci: Carta kawalan; COVID-19; kajian varians

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^*Pengarang untuk surat-menyurat; email: wana_am@um.edu.my