We have watched with increasing befuddlement as the second wave of Covid-19 has surged past the first over the past month, and increasingly we have heard of people in Bangladesh who took at least one dose of the vaccine not only getting infected again, but also in some cases falling severely ill and even dying. This week we received some indication of why this might be. The South Africa variant of the novel SARS-CoV-2 coronavirus has taken over as the most dominant variant in Dhaka, according to a recent study by the International Centre for Diarrhoeal Disease Research, Bangladesh (Icddr,b).

The study, conducted from March 18-24, analysed the genomic sequence of 57 samples from Covid-19 patients and found that over 80% (46 samples) matched the South Africa variant, according to media reports.

Icddr,b researchers also analysed the genomic sequence 30 samples from March 5-11, and 99 samples from March 12-17. The South Africa variant was not found from March 5-11, but it matched 64% of the samples from March 12-17. The Icddr,b is continuing genomic sequencing of samples collected after March 24, with results expected in the days ahead.

The first case of the South Africa variant in Bangladesh was detected on February 1. Experts from the Gonoshasthaya-RNA Molecular Diagnostic and Research Centre, Jahangirnagar University microbiology department and Brac University pharmacy department confirmed the variant after sequencing the genome of clinical samples. Given that the Oxford-Astrazeneca vaccine, that Bangladesh started rolling out as part of its vaccination campaign in February. Readers may recall that South Africa put its rollout of the Oxford-AstraZeneca vaccine on hold in February after a study showed "disappointing" results against its new Covid variant. Scientists say the variant accounts for 90% of new Covid cases in South Africa. The trial, involving some 2,000 people, found that the vaccine offered "minimal protection" against mild and moderate cases.

To date, 12 COVID-19 vaccines have received authorization for use in at least one country, and many more vaccine candidates are undergoing clinical trials to test their safety and efficacy. Yet, like other viruses, SARS-CoV-2, the coronavirus that causes COVID-19, naturally undergoes mutations in time. These mutations can be negligible or affect how infectious or likely to cause severe disease a virus is. Unfortunately, the novel coronavirus has now already demonstrated that it is a moving target, against which there is no room for complacency. Scientists have already said we must not let down our guard by starting to neglect the public health protocols that have come into place over the past year. And even vaccination, we must realize, does not provide guaranteed protection.