Source ForPressRelease.com

Suburban Diagnostics, in their attempt to objectify their diagnostic and management strategies, conducted a research on 83 patients with a known history of COVID-19. These patients were followed up on with serial antibody tests to study the sero-conversion and the trend of antibody response post infection. Out of the 83 patients, 64% (53 patients) had symptomatic COVID-19 infection and 36% (30 patients) had completely asymptomatic infection.



When followed up for 120-150 days post infection, 92% were positive for antibodies and 8% were still negative. Of the patients who completed 180 days post diagnosis, 90% were antibody positive. This figure is liable to change once all the patients being followed up complete 180 days and are tested.



When following up with antibody testing amongst the 83 patients, 88% showed a rise in titres at 60-90 days, while 4% cases showed a dip and 8% cases were still non-reactive. At 90-120 days, 55% cases showed rising antibody values, 35% showed a dip in these values while 2% cases showed a plateau in antibody values and 8% were still non-reactive. At 120-150 days, 37% cases showed rising antibody values, 55% showed a dip in these values and 8% were still non-reactive.



One more study conducted on a total of 200 patients by Suburban Diagnostics was to understand the concordance between the rapid antigen test and the RT-PCR test with different cycle threshold (CT) values. In this study, the patients were evaluated for the COVID-19 infection by the rapid antigen method and the RT-PCR method, both. The conclusion of the study is that the rapid antigen test was 100% specific with no false positives found and had a 60% sensitivity compared to the RT-PCR test. It showed a lower sensitivity of 32% in asymptomatic patients. The CT value correlation showed that 63% cases that the antigen test proved negative but the RT-PCR test proved positive had borderline CT values corresponding to low viral titres. A RT-PCR analysis was also processed on more than 3.7 lac samples declared 70.7% results were negative and 29.3% were positive.



In relation to antibody development, a rising trend has been seen since July in the city of Mumbai and a falling trend of COVID-19 virus positivity rate has been seen from July till November after a peak in July, 2020.