<span style="color: #222222;">In Kerala, the second phase of sero-surveillance study  conducted by Indian Council of Medical Research (ICMR) to ascertain the extent of spread of COVID-19 began today. The survey will cover Palakkad, Thrissur and Ernakulam districts. The first phase of sero-surveillance was also held in these districts.<br />''<br />''The survey is of immense significance as the result will reveal whether the disease-control methods adopted so far have been successful and also the  percentage of the population that has developed immunity to the disease.<br />''<br />''Presently, there are 20,300 active cases in Kerala. The ICMR will use the sero-surveillance result as a reference to revise its strategy against COVID-19.</span><br />