The first Covid-19 case was detected on March 8 last year and eventually spread all over the country due to people leaving Dhaka en masse after the March 26 to April 4 "national public holiday" was declared by the government in 2020, according to a recent study.

A genomic epidemiology consortium comprised of the Institute of Epidemiology, Disease Control and Research (IEDCR), Bangladesh; icddr,b and Institute for Developing Science and Health Initiatives (ideSHi) in collaboration with local and international institutions have published a scientific paper in Nature Microbiology titled "Genomics, social media, and mobile phone data enable mapping of SARS-CoV-2 lineages to inform health policy in Bangladesh."

"Bangladesh reported the first Covid-19 case on 8 March, 2020. To contain the spread of the virus, the Government of Bangladesh announced a national public holiday with stay-at-home order on 23 March 2020, which was effective from 26 March to 4 April and later incrementally extended until 30 May 2020," the release said.

"The population mobility data collected from Facebook and three mobile phone operators showed an important link between population movement and the spread of SARS-CoV-2. It indicated a mass migration out of Dhaka to all areas of the country on 23-26 March 2020. Together, these mobility data are consistent with the transmission of SARS-CoV-2 out of Dhaka to the rest of the country during the first wave," according to the study.

"Combining population mobility and genomics data revealed a direct link between the transmission of three dominant lineages and the spread of the disease across the country during the first wave."

The consortium sequenced another 85 SARS-CoV-2 specimens in April 2021 collected between November 2020 and April 2021. Their analysis of the first wave and the country-wide spread through inter-city travel led the authors to work directly with the government on the detection of variants of concern Alpha and Beta in Bangladesh, the release added.

The consortium has been supported by the Directorate General of Health Services (DGHS), Bangladesh; the Aspire to Innovate (a2i) Program, Bangladesh; University of Bath, UK; Wellcome Sanger Institute, UK; Harvard TH Chan School of Public Health, USA.