- 100 % people develop antibodies after 2nd dose
- People aged 20 and 50 grew stronger antibody response
- Those above 60 had less antibody response
- 70% deaths are of people above 60
A hundred percent of the people who took both the shots of Oxford-AstraZeneca vaccine developed antibodies, but female recipients showed stronger response than their male counterparts, according to a research.
The study titled "Antibody response after Covid-19 vaccination in different age groups" had 500 participants who received vaccine doses between 1 February and 20 May at Sheikh Hasina National Institute of Burn and Plastic Surgery, Dhaka Medical College Hospital and Bangabandhu Sheikh Mujib Medical University Hospital. Of them, 360 were men and 140 women.
The level (titer) of antibodies in most of them was more than 6, whereas, researchers said, antibody titer 6 in one's blood indicates enough immunity to fend off Covid infection. In women, antibody titer was even higher.
Since antibody response in women is better than men, "if we prioritize women in the vaccination programme, it will be easier to achieve herd immunity", said Ashraful Hoque, principal investigator of the study and assistant professor, blood transfusion at the National Institute of Burn and Plastic Surgery.
But the rate at which women completed registration for the jab and received it is much less than that of men. Ashraful suggested making the registration process easier to bring more women under the coverage of the inoculation drive.
The drive has, however, been slowed down due to the suspension of vaccine supply from the Serum Institute of India amid a surge in infections in the neighbouring country.
Bangladesh started its inoculation drive on 7 February and delivering second doses began two months later. So far, more than 58 lakh people took the first dose and 40 lakh people completed the immunisation course.
During the research, antibody titer was tested at least 28 days after the first shot and 14 days after the second shot. But antibody response was stronger when test was done days after the schedule.
People aged between 20 and 72 were studied upon to understand how much protection the vaccine could provide. Those above 60 years had less immune response and the response was good for people between 20 and 50 years.
The data of the health directorate shows that 70% deaths caused by Covid-19 were of people above 60 years.
Bangladesh now has only 3 lakh doses of vaccine out of 1.2 crore doses it received from India. About 14 lakh people are uncertain about when they will possibly get their second dose.
Dr Ashraful said the study results indicated the necessity of giving second shots to those who might have less antibody response – people aged over 60 years -- on a priority basis.
"If their vaccination remains incomplete even 16 weeks after the first shot, they may get infected by the virus and give rise to its new variants."
Antibody titer was tested in all the participants before they had been vaccinated as part of the research. Eighty of them already had antibodies but 40 of them had come negative in RT-PCR tests.
Those, who already had antibodies before being vaccinated, had the antibody level after the first shot as strong as those without antibodies before vaccination had after getting the second dose.
Dr. Forhad Uddin Hasan Chowdhury, co-investigator of the study and registrar of the internal medicine department of Dhaka Medical College Hospital, said vaccine would help reduce the severity of the disease and the mortality rate.
"How much protection antibody will give cannot be said. It is now time to study how long immunity induced by the vaccination will last."