National Health Laboratory calls for participants to test antibody tests 16 Mar 2021 The NHLS will collect samples from at least 300 participants and bank them for use in future rapid or serological tests. (Photo by Naveen Sharma/SOPA Images/LightRocket via Getty Images) The National Health Laboratory Service is looking for people to participate in a study aimed at evaluating the performance of Covid-19 rapid antibody tests. Samples collected from the participants will be used to create banks of known positive and negative controls that scientists around the country can use to quickly and accurately test any rapid or serological tests, which check for antibodies to the novel coronavirus.