IS TEST POSITIVITY A GOOD CONDUCTOR OF COVID CASELOAD?

IS TEST POSITIVITY A GOOD CONDUCTOR OF COVID CASELOAD?

Subject : Science & tech

Context: The second surge in the pandemic has been rather alarming. The number of positive cases has been rising in much of the country, in urban as well as rural areas, since the middle of March.

Concept :

• Test positivity is a good benchmark at the earliest stages of the epidemic. Once the infection has spread sufficiently through the population, the chain of infection is no longer clear.
• In such situation, the test positivity may not reduce even when the number of tests is increased. This is a bad situation of course, since it is indicative of widespread infection, with many asymptomatic cases.
• Test positivity can be also used as an indicator to mark the decline of the epidemic. As the epidemic ends, the number of tests being done will decline and the test positivity is likely to stay constant or decline as well.
• However, as the number of tests decline, if an increase of test positivity is observed, then the reduction in the number of tests should be taken as a matter of concern. It is then necessary to increase the number of tests.
• As we saw, test positivity by itself does not give enough information to understand the progress of the epidemic at all stages.
• Moreover, there can be many infected people who are asymptomatic and who therefore remain undetected.
• Such asymptomatic people can infect others, and it is necessary to estimate their number to understand the progression of the epidemic. That is where the Case Fatality Rate (CFR) comes into play.

Case fatality rate

• Case fatality rate, also called case fatality risk or case fatality ratio, in epidemiology, the proportion of people who die from a specified disease among all individuals diagnosed with the disease over a certain period of time.
• Case fatality rate typically is used as a measure of disease severity and is often used for prognosis (predicting disease course or outcome), where comparatively high rates are indicative of relatively poor outcomes.