NEW DELHI : The Council of Scientific and Industrial Research (CSIR) is conducting a survey in its 38 laboratories and institutes across India to gauge the serological prevalence among its employees and also understand how long antibodies against COVID-19 remain active, officials said.The exercise aims to target 10,000 CSIR employees and their family members in the age group of 19-60 years, said Shantanu Sengupta, a scientist with CSIR's Institute for Genomics and Integrative Biology (IGIB) in Delhi, which is coordinating the sero-survey.Sengupta said the exercise has already begun and it is expected to get completed by September.