Received: 19 September 2019
Accepted: 9 March 2020
First Online: 18 March 2020
Ethics approval and consent to participate
: The Ethics Review Committee of the Medical Research Institute of Sri Lanka granted ethical clearance. Written informed consent was obtained from each of the selected participants prior to data collection. In case of a child (age < 18 years), written informed consent was obtained from the parents or from the guardian. Confidentiality was maintained while handing over individual serological reports.
: Not applicable.
: “The authors declare that they have no competing interests” in this section.