Dr Mohammad Didare Alam Muhsin :
When the outbreak of Covid-19 infections was brought under control by January-February this year, many might have thought that the Covid-19 chapter was coming to an end in the country. There was reluctance among people in following health protocols. The country has witnessed a busy time with weddings, gatherings, meetings and touring all around. However, since mid-February the infection started to increase again and took a steep upward turn from mid-March.
What has been the reason behind this fresh surge? Undoubtedly, negligence to health protocols has played an important role here, but the steep rise in infection was indicative of something else. Finally, things became clear from two recent studies conducted independently by CHRF and ICDDR,B. In the studies completed by the two organizations in the third week of March, it was found that 80-81 percent of recent COVID-19 patients were infected with the South African variant of coronavirus and 10-12 percent with UK variants. For the first time in the country, UK and South African variants were reported on January 6 and February 6 respectively. As per various research outcomes, the infection of UK variant continued to increase till the 2nd week of March. It was soon replaced by the South African variant, which reached 81 percent by the end of March. Although these studies were based on a small number of samples, they did provide a rough picture of the overall dynamics of the spread of these variants in the country.
Scientists have identified four variants of the coronavirus in Bangladesh, namely the UK variant (B.1.1.7), the South African variant (B.1.351), the Brazilian variant (P.1) and the California variant (B.1.427) and B.1.429). The Brazilian variant was also reported to have been identified in the country last March, but there is probably no report of the presence of the California variant yet. UK, South African and Brazilian variants – all share a common mutation in their spike proteins called N501Y, which helps them to bind better to the ACE2 receptor on the human cell. This is the underlying reason why they are more contagious than the original version (wild type) of the coronavirus. According to the information, the UK variant is 30-50%, the South African variant 50% and the Brazilian variant 150% more contagious than the original coronavirus.
The South African variant has two more important mutations, E484K and K417N in the spike protein. Because of these mutations, antibodies against the original virus can not bind well with the virus. This means that a person who has already been infected with the wild type of coronavirus may be re-infected with this variant. Moreover, vaccines that have already been developed targeting the original coronavirus may not provide adequate protection against this variant. Dr. Anthony Fauci, the top US infectious-disease expert, says that the South African variant is the most concerning one because it might render vaccines less effective due to mutations that help it ‘hide’ from antibodies developed after vaccination or a previous bout of COVID-19. Notably, similar mutations (E484K, K417T) have also been observed in the Brazilian variant.
Now, let us consider the status of these mutations in terms of morbidity and mortality. According to the UK government’s New and Emerging Respiratory Virus Threats Advisory Group (NERVTAG), the UK variant has a 30-40% higher risk of death. While the South African variant does not appear to be more lethal, it has been observed in South Africa that increased pressure on hospitals, due to rapidly spreading infections, increased the risk of death. According to reports, doctors in our country have found significant lung damage (30-40%) in quick time in many patients with recent infections. About 40-50 percent of hospitalized patients need oxygen. Moreover, the symptoms of the disease have also changed. Instead of the usual symptoms like cough or fever, many people are coming up with various symptoms including headache, diarrhea and abnormal behavior and the test is proving to be positive. Another significant aspect of the infection this year is that young people are getting infected more here.
Perhaps a major concern at the moment is: how well the existing vaccines are able to protect against these variants, especially the South African variant. One study found that the AstraZeneca vaccine is almost ineffective in preventing mild infections of the South African variant. According to another study, the effectiveness of Novavax against mild Infections is about 50 percent. However, it is not clear how much protection AstraZeneca or Novavax vaccines can provide against severe infections. A large-scale study on the Johnson & Johnson’s vaccine has shown that it is 85% effective in preventing severe infections of the South African variant. A relatively small study conducted with the Pfizer’s vaccine found that it was 100 percent effective in preventing even mild infections of the South African variant.
The country has already launched a vaccination program. We are taking the AstraZeneca vaccine. Since the South African variant seems to be playing a major role in the fresh surge of the infection now, and according to the information available so far, the effectiveness of the AstraZeneca vaccine against this variant is questionable, we need to do more research on it and should actively consider alternative vaccines. In addition, it is important to take immediate steps to determine the region-wide spread of different variants of the coronavirus by conducting large-scale sequencing programs on samples collected from different regions of the country, especially highly COVID-affected areas. Otherwise, the vaccination program may fail to deliver the desired results.
(Dr Muhsin is Professor of Pharmacy, Jahangirnagar University).
