Antibody no guarantee for herd immunity

Developing antibody to Covid-19 primarily gives the impression of immunity to the deadly disease. A survey conducted in Dhaka City jointly by the Institute of Epidemiology Disease Control and Research (IEDCR) and the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) finds that 45 per cent of inhabitants living in different wards and 74 per cent of the city's slum-dwellers have developed antibody in their system. This is quite intriguing. It means that half the population of this mega city was attacked by coronavirus at one time or other. Since the survey was conducted between April and mid-July in city wards and between mid-July and mid-August in slums, the number of Covid-19 patients by that time comes approximately to 10,000,000. This is many times more the number of confirmed cases tested in different designated laboratories of the city. Then why were not more patients seeking admission to hospitals? The answer is simple: 82 per cent of them were asymptomatic.
Such patients are roaming about freely or even staying home, doing all they are supposed to do as a daily routine without ever knowing they caught the disease. The impression is that the Dhakaites have developed herd immunity. Had it been the case without an iota of doubt, the occasion would surely be a cause for great celebration. To laymen, it appears like herd immunity but appearances are deceptive. The issue of herd immunity is debatable and it is still unclear how long the antibody in an individual will remain effective. This expert view should be taken seriously by both groups of people -- those who were confirmed to have developed antibody and those who have not yet got the disease. Precaution is necessary for both groups in the interest of their own and also of others around them.
Notably, the presence of antibody in 45 per cent of people in the city's residential areas was found by mid-July. Three more months have passed by this time and the percentage has most likely gone up. Delhi recorded a spike of 80 per cent on the basis of statistics of May. A continuous and more extensive survey could have given a more representative picture of the disease. The one done in Dhaka covered 3,227 households with funds from the USAID and the Bill and Melinda Gates Foundation. The two organisations responsible for conducting the survey may approach the US agency and the foundation or other such agencies for undertaking a follow-up study, particularly when the threat of a second wave of virus attack looms large.
All this now points to the fact that the danger from the disease is far from over. Taking it casually as people in this city and other crowded urban centres have started doing is a recipe for disaster. Neighbouring India's experience should be a lesson for the people here. The death toll has surpassed the 100,000 mark there. One silver lining is that people can protect themselves if they maintain the already proven health protocols which fortunately are not hard to comply with. Wearing masks in public places tops the list and social distancing comes next. If the second one cannot be helped compromising, the best way is to have a thorough bath with soap on return home.