The BA. 5 sub-variant of Omicron coronavirus is predominant in Bangladesh especially in Dhaka city as the fourth wave of the coronavirus transmission is going on in the country for last few weeks.
During the last six weeks (14 May to 24 June 2022), Omicron BA.5 became the most predominant sub-variant. During this period, 51 out of 52 coronavirus positive cases were identified as BA.5 sub-variants and one BA.2 by using complete genome sequencing, said a study of icddr,b.
According to the icddr,b, newer iterations of the Omicron variant, BA.4 and BA.5 are spreading rapidly and poised to outcompete past versions of the virus, extending the current COVID-19 surge. Omicron BA.4 and BA.5 were first identified in South Africa in January and February 2022, respectively.
Limited data indicate that the newer sub-variants caused fewer hospitalisations and deaths compared to previous ones. As part of the countrywide COVID-19 testing network, icddr,b has been testing COVID-19 patients and monitoring SARS-CoV-2 variants, it added.
The icddr,b said the Omicron variant in Bangladesh was first identified on 6 December 2021.
Initially, the majority of COVID-19 positive cases were BA.1 (during the first two weeks of January 2022). The sub-variant BA.2 emerged from the third week of January 2022, and circulated until the first week of April 2022 by replacing the BA.1 over time.
It said during 9 April to 13 May 2022, no sequencing was possible due to very low COVID-19 positivity rate and high Ct values of the positive samples. The first suspected Omicron sub-variant BA.5 in Dhaka was detected on 19 May 2022.
The icddr,b study illustrates how SARS-CoV-2 variants are outcompeted one by another over time, which underscores the continuation of variant surveillance for a regular update on the emergence of new variants.
As per clinical data and vaccination history was available for 40 Omicron BA.5 infected patients, it was found that 16 were male and 24 were female. Some 39 patients had mild to moderate symptoms, and one had no symptom and only one was hospitalised for one day.
The report said 11 were re-infected for the second time and seven for the third time while 38 patients had received at least one dose vaccine. Among them, 16 had received booster doses of vaccines, 21 had two doses, and one had received only one dose.
However, none of the 40 patients had travel history, the study added.
It further said the severity of the disease caused by Omicron BA.5 sub-variant among the study population is low. However, the recent countrywide upsurge of COVID-19 cases as well as hospitalisation warrants continuation of public health and social measures to minimize the transmission of the virus.
The icddr,b study said people should practice the precautions –vaccination is key, get vaccinated, keep wearing well-fitted facemask, maintain physical distancing, even though vaccinated or naturally infected and wash hands with soap and water frequently.