Antibodies were found in 98 percent people who received full (double) dose of Oxford-AstraZeneca vaccine produced by Serum Institute of India -- called Covishield -- finds a study conducted by Bangabandhu Sheikh Mujib Medical University (BSMMU).

Vice-Chancellor of BSMMU Prof Dr Sharfuddin Ahmed led the research titled "Hematological Parameters and Antibody Titre After Vaccination Against SARS-CoV-2". The results were published this morning.

A total of 209 Covid-19 vaccine recipients volunteered for the study. Samples were collected between April and July this year. Three-quarters of the participants were male, and more than half were healthcare professionals.

A total of 31 percent participants have had Covid-19, while more than half were suffering from diabetes, high blood pressure, asthma, and other conditions. The study suggested that no difference was observed in the production of antibodies after vaccination.

"Those who have not developed antibodies had underlying health conditions like cancer. The number of antibodies ranged between 300 and 1000 au per milliliter blood in most vaccine recipients," Prof Dr Md Salahuddin Shah, co-investigator of the study and also the chairman of the Hematology Department at the BSMMU, told The Daily Star.

"Although the sample size is small, this study suggests that Covid-19 vaccines are efficacious. Our study will partly help policymakers decide on booster doses," he said.

A total of 42% of participants reported side effects after vaccination, with mild symptoms in all cases.

The study also found that those with records of prior Covid-19 infection before vaccination experienced higher levels of antibodies.