# Country-Based COVID-19 DNA Sequence Classification in Relation with International Travel Policy
## 2 Data and Method  
### Data  
There are three datasets utilized in this study: DNA sequences, the number of confirmed cases and deaths from COVID-19, and the international travel policy data. The first and primary data were sourced from the official Global Initiative on Sharing All Influenza Data (GISAID) website [25]. Our focus centered on SARS-CoV-2 nucleotide sequences categorized as complete (sequence length > 29,000 bp) and high coverage (only entries with less than 1% undefined bases) from nine ASEAN countries: Brunei, Cambodia, Indonesia, Laos, Malaysia, Philippines, Singapore, Thailand, and Vietnam. Specifically, we selected DNA sequences with a collection date range from 1 July 2021 to 31 December 2021. Referring to the website, in comparison with the other half-year periods over three years, each country submitted a relatively larger number of sequences during this timeframe,as indicated in Table 1. This sufficient dataset is anticipated to provide comprehensive information, addressing the potential limitations associated with data scarcity. Additional information regarding the dataset downloaded from the GISAID website in the second half of 2021, taking into account variants of concern, reveals that the Delta variant dominates the variant distribution in ASEAN countries. As illustrated in Table 2, except for Cambodia and the Philippines, other countries possess DNA sequences comprising more than 94% Delta variant, with Brunei and Vietnam exclusively consisting of this variant in their datasets. In the subsequent classification process, we conducted the classification using the all available DNA sequences and also exclusively using the Delta variant sequences, aiming to observe the impact of this variant on the classification results. The second dataset consists of the impact of COVID-19 in each ASEAN country accessed from official data collated by Our World in Data [26]. This dataset includes the number of daily new confirmed cases, daily new confirmed deaths, cumulative confirmed cases, and cumulative confirmed deaths per million people. We focus on data spanning the past three years, from 1 March 2020 to 28 February 2023. By aggregating the daily value per week, we plotted the number of weekly confirmed cases and deaths, as depicted in Figure 1. Based on the figure, the pandemic conditions in most ASEAN countries were relatively severe from 1 July 2021 to 31 December 2021 as illustrated by the highest number of weekly confirmed deaths and a significant number of weekly confirmed cases per million people in this period. This contextual information is invaluable for analyzing the DNA sequences classification results in connection to the pandemic situation. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Country Name**} & \multicolumn{6}{c}{**Number of Sequences Submitted in:**} \\ \cline{2-7}  & **January–June** & **July–December** & **January–June** & **July–December** & **January–June** & **July–December** \\  & **2020** & **2020** & **2021** & **2021** & **2022** & **2022** \\ \hline Brunei & 5 & 2 & 2 & 488 & 118 & 54 \\ Cambodia & 20 & 26 & 460 & 1487 & 578 & 86 \\ Indonesia & 204 & 581 & 4186 & 4428 & 715 & 332 \\ Laos & - & - & - & 862 & 233 & 12 \\ Malaysia & 165 & 326 & 1341 & 5777 & 2800 & 848 \\ Philippines & 29 & 337 & 4293 & 3292 & 24 & 148 \\ Singapore & 1092 & 363 & 1664 & 7171 & 969 & 303 \\ Thailand & 307 & 144 & 2161 & 6532 & 1277 & 398 \\ Vietnam & 121 & 55 & 275 & 1658 & 411 & 15 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Number of SARS-CoV-2 DNA sequences submitted to the GISAID database by each ASEAN country in half-year periods over 3 years, categorized as complete and high coverage.