Covishield, the Covid-19 vaccine of Oxford/ AstraZeneca made in Serum Institute of India, has shown a “robust” immune response among the Bangladeshi adults, an interim analysis of the icddr,b and IEDCR study finds.
Dr Firdausi Qadri, Senior Scientist at icddr,b, termed it a “great news indeed”.
“We now know that the Covishield vaccine induces robust immune response in Bangladeshi adults,” she said.
Commenting on the importance of the study, Prof Tahmina Shirin, Director of the government’s disease monitoring agency, IEDCR said, “Our analysis confirmed that the vaccine works and people should get it when their turn comes.”
“However, everyone should continue wearing face masks and maintain physical distancing along with personal hand hygiene to keep themselves and their loved ones protected from COVID-19,” she said.
In an interim analysis, scientists at icddr,b and the IEDCR with support from the United States Agency for International Development (USAID) measured levels of SARS-CoV-2 IgG antibodies in the blood of 120 participants before vaccination and then at one and two months after vaccination with the first dose of the Covishield vaccine.
The vaccine recipients were aged between 40-73 years of age (average age of 49 years) comprising individuals with or without history of prior COVID-19, and from Dhaka city.
It was found that one month after vaccination 92% of the people who received the first dose of vaccine to have high immune response (geometric mean concentration of antibody against the virus 2,586 ng/ml), and 97% of the people to have even higher immune response (GMT 3,460 ng/ml) two months after the first dose of vaccination.
Cut-off for a positive IgG antibody response to the spike protein of SARS-CoV-2 was set at 500 ng/ml using 355 serum samples collected prior to the onset of the pandemic.
Some 46 participants (average 48 years) with previous RT-PCR confirmed SARS-CoV-2 infection history (between April 2020 – January 2021) were also included in the analysis.
Participants who had a previous infection with SARS-CoV-2 (1 month or earlier before vaccination) showed more robust response after receiving the first dose of vaccine.
A fourfold higher magnitude of antibody response was seen among these participants at two months after receiving the first dose vaccine.
Dr Firdausi Qadri said they would continue working on evaluating the neutralising ability of the antibody as well as the T and B cell responses. “We will also continue assessing the effectiveness of the vaccine in our setting.”
icddr,b and IEDCR have started a large-scale study at 12 sites in eight divisions across Bangladesh that will involve about 6,300 participants who will complete their full course of vaccination. Participants will be followed up for two years in a longitudinal design for assessing antibody responses after vaccination (day 0 and months 1, 2, 3, 6, 12, 18, and 24) to determine the longevity of antibody response.
The first part of the study is funded by the USAID and partially by the Bill and Melinda Gates Foundation. Currently both IEDCR and icddr,b are looking for more funds to complete the study.
The Covishield vaccine is developed by the Oxford University vaccine group, marketed by AstraZeneca and manufactured by Serum Institute of India.