Even though Bangladesh logged 15,61,463 Covid-19 cases as of Friday, experts believe around 70 percent population of the country may have contracted the virus and developed natural antibodies. Some experts think that the country is close to reaching the herd immunity threshold while some others say a comprehensive serosurveillance report is necessary to reach a conclusion over it. They all, however, viewed that it is necessary to inoculate around 70-80 percent of people of the country to attain herd protection against the Coronavirus as any virulent new variant like Delta can emerge and dodge people’s natural immune protection. Read Kindergartens in Chandpur struggle to recover from Covid-19 shocks, many stay closed  Herd immunity is a concept based on the body's immune resistance to the spread of a deadly disease (bacterial or viral infection) and it can be obtained in two ways -- naturally through infections of the majority of the population and artificially through vaccinating around 80 percent of the population of a country. Official data on infection, vaccination As per the data of the Directorate General of Health Services (DGHS), Bangladesh reported 15,61,463 cases till Friday while the positivity rate was 2.77. The daily-case positivity rate in the country remained below 5 percent for over last two weeks. According to the Directorate General of Health Services (DGHS), a total of 35,829,418 people received the first dose of vaccines while 17,795,120 ones both doses as of October 7. The country has so far collected 64,568,420 doses AstraZeneca , Pfizer, Moderna and Sinopharm vaccines. Read DU to collaborate with AFC Biotech to develop Covid-19 vaccine Meanwhile, Health Minister Zahid Maleque on Saturday said around five crore people have already been vaccinated while 50 percent will be brought under the vaccination by December next. He said they also have a plan to vaccinate 70-80 percent people of the country by March next year. Debate over antibody, herd immunity Based on some studies on samples collected from both symptomatic and asymptomatic Covid positive individuals, Ramon Magsaysay Award-winning Bangladeshi scientist Dr Firdausi Qadri said 60-70 percent people of Bangladesh have gained some types of antibodies against Covid-19. Read: Bangladesh unlikely to reach Covid herd immunity anytime soon: Expert

Researchers found the presence of Covid antibodies among 35 % people in three upzilas of Jashore district, suggesting that these people either contracted the virus or came in close contact with infected patients. The Genome Centre of Jashore University of Science and Technology (JUST) revealed the study findings on Saturday, after examining the samples of 400 people from six areas in Jhikorgachcha, Chougachcha and Sadar upazilas. Read: Covid vaccination reduces chances of hospitalization, mortality: IEDCR study The study was conducted through rapid antibody tests after collecting blood samples of the people. According to the research, natural antibodies were found among 38% members of those families where there were Covid-19 patients, and they were found tested positive through RT PCR. Besides, antibodies were detected among 24% people who lived near the houses of Covid positive patients. The people who have got vaccinated were not included in the research. According to the research report, it has been proved that the number of asymptomatic Covid carriers is higher and they are roaming around freely. Read: CVASU study confirms Delta has taken over as dominant strain