Outbound travel from Dhaka primary cause of infections rising: Study

A joint study has revealed that the trend of leaving Dhaka after the government declared a general holiday from 26 March last year to prevent the infection is the main reason for the spread of the virus across the country.

The researchers said that by analysing the genetic characteristics of SARS-CoV-2 with data obtained from people leaving Dhaka between 23 March and 26 March, it was found that outbound travel from Dhaka during that period was the primary cause of infections increasing.

The study in nature microbiology titled "Genomics, social media, and mobile phone data enable mapping of SARS-CoV-2 lineages to inform health policy in Bangladesh", suggested that evidence-based national policies are necessary to curb local Covid-19 infections.

A genomic epidemiology consortium comprised the Institute of Epidemiology, Disease Control and Research (IEDCR), Bangladesh, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), and the Institute for Developing Science and Health Initiatives (ideSHi), in collaboration with local and international institutions, published a scientific paper in this regard on Tuesday, said a press release.

Initially, the genomes of 391 Covid-19 viruses collected from different parts of the country were analysed between March and July 2020. The analysis shows that the first Covid-19 outbreak in Bangladesh might have taken place in 2020. In mid-February and later, the virus spread further through domestic and international aviation.

Based on the reasons for the spread of the first wave, the government took further necessary steps to prevent the spread of the virus, including a ban on inter-district travel.

Commenting on the outcome of the study, IEDCR Director Professor Dr Tahmina Shirin, also a senior author of the article, said, "Our consortium has provided many invaluable insights that helped decision-makers to devise essential real-time policy decisions. These include the provision of mandatory quarantine and isolation of travellers arriving from countries where a variant of Covid-19 was dominating, imposing lockdown measures, restricting inter-city movements of people, and banning all international flights from high-risk countries to Bangladesh."

Dr Lauren A Cowley, University of Bath, UK, and one of the first authors of the article, said, "By combining different data streams from genomic and mobility data, we were able to provide new resolutions to how SARS-CoV-2 spread in Bangladesh. This study showcases the incredible capacity for genome sequencing built in Bangladesh, which will continue to be used during the ongoing Covid-19 pandemic as well as in future outbreaks of other pathogens."

Dr Firdausi Qadri, a Senior Scientist at the icddr,b and a senior author of the article, said, "As more mutations accumulate in the SARS-CoV-2's genetic code, there will be more variants some of which could have the strength to breakthrough natural or vaccine-induced immunity. This is already becoming evident and Bangladesh has experienced the second wave with the Beta variant and is currently battling the third wave with the Delta variant. Real-time genomic surveillance is critical to understanding the efficacy of these vaccines and protection from previous Covid-19 infections, and to devise relevant strategies for Bangladesh and beyond."

Facebook Data for Good, Grameenphone, Banglalink, and Robi Axiata Limited, provided population movement data. The Bill and Melinda Gates Foundation and the Government of Bangladesh supported the in-country sequencing of SARS-CoV-2 Bangladesh samples.