The Ministry of National Health Services, Regulations & Coordination has issued an official handout according to which a screening exercise for assessing the presence of Coronavirus antibodies was conducted in the Islamabad Capital Territory during June 2020. Review of data set and sample procedures validation activity, along with peer review of data for control of confounders is currently underway, for the said activity. In the absence of completion of all these follow-up confirmatory processes, the community based preliminary findings should not be used to estimate the disease burden at the population level, according to the Ministry.
Sero-prevalence surveys at the population/community levels are usually conducted as a preliminary screening exercise, to understand the patterns of immunity against certain diseases. These screening processes/results and samples at the population level are then required to be validated through further laboratory tests and peer review of the data including the statistical analysis for control of confounders; factors that might be confusing the true picture. Experts maintain that positive predictive value of a single screening test in low prevalence situatuons/community is very low and should not be taken as a stand alone result.
The antibody presence at the population level is not necessarily reflective of presence of disease, but the body’s reaction and possibly presence of immunity against the disease, hence such surveys are usually a multi-stage, multi-procedure studies. A good example is measles-a viral disease of children. A serological study of measles at the population level is reflective of presence of antibodies across the population, and in no way can be translated into the derivations that these many are the number of measles cases at a given point in time.
In this backdrop, the recent media reports reflecting the preliminary results of the ICT sero-prevalence survey as the finalized estimates for Coronavirus (COVID-19) expected cases in ICT territory, should not be used to make inferences about the burden of Covid 19 for the ICT. The actual volume of cases that might have been exposed to Coronavirus in ICT should only be derived, once all the confirmation and validation processes, and requisite peer-reviews are completed. The said activities are understood to be completed in the coming weeks, based on which the Mo NHSRC will officially announce the results of the said survey.