Using Test Positivity Rate (TPR) as an Indicator for Strategic Action in COVID-19: A Situational Analysis in Kerala, India

Abstract

Administrators and policymakers have relied on test positivity rate (TPR) for making policy decisions regarding local, regional, and national lockdowns. It has the advantage of easily available data with an easy technique for calculation on day-to-day basis. However, concerns are being raised regarding its use as a sole indicator for determining movement restrictions and lockdowns. The present review provides a perspective of the alterations in TPR in Kasaragod district of Kerala during the first half of 2021. The variations in the number of antigen and reverse transcription polymerase chain reaction (rt-PCR) tests along with the trend of proportion of rt-PCR test are depicted. In places like Kerala where primary care system and contact tracing is comparatively robust than several other regions, testing the appropriate persons in a timely fashion alone is sufficient to cause an upswing in the TPR. Rather than daily change, the overall change in a larger time frame of 1 to 2 weeks could give early warning regarding the emergence of a new wave. TPR alone may not be able to reflect the transmission patterns of COVID-19. Using 7-day median value of TPR along with weekly tests done per 10,000 population, 7-day rolling average of active cases per 10,000 population, or daily number of new positive cases per 10,000 population could bring out a more composite indicator. Such an indicator reflecting the disease dynamics at regional levels will enable people to improve their livelihood without compromising on COVID-19.