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s Indian Journal of Medical Microbiology 39 (2021) S1–S133 ANTIBODY RESPONSE AMONGST NUCLEIC ACID AMPLIFICATION TEST (NAAT) CONFIRMED COVID-19 POSITIVE PATIENTS: A CROSS SECTIONAL STUDY Gurpreet Singh Bhalla, Rajat Shukla, Kuntal Bandyopadhyay, Rachana Warrier. Military Hospital (Namkum) Background:COVID-19 pandemic has caused immense loss of lives, enormous devastation and has affected lives globally. Timely diagnosis is necessary to contain its spread. While it is important to test symptomatic individuals and high -risk contacts through reliable and confirmatory test (NAAT) to find out the positive cases of COVID -19, it is also vital to check their immunity status through serological tests to find out the varied immunological response in the affected population. Methods:All NAAT confirmed COVID-19 patients were included in the study. With a repeat respiratory sample for NAAT, simultaneous serum sample was taken for detection of IgM and IgG antibodies. Data was compiled and analyzed statistically. Results:During the first repeat NAAT, 71.43% had mounted an antibody response, whereas, 28.57% had no response. Irrespective of the antibody status, 68.57% tested positive for SARS-CoV-2 virus in NAAT. Though the number dwindled on second repeat NAAT, it raised important questions regarding humoral response and its clinical and diagnostic applicability. Conclusions:Not all COVID-19 patients mount a humoral response due to yet unexplained factors. Also, exclusive dependence on serology assays will miss diagnosis in these patients. More research is needed for description and applicability of humoral response in COVID-19 patients. https://doi.org/10.1016/j.ijmmb.2021.08.257 EVALUATING CLINICO-DEMOGRAPHIC PROFILE, COMORBIDITIES, DIAGNOSTIC TESTS USED FOR CONFIRMATION AND OUTCOME OF COVID 19 PATIENTS PRESENTING AT A PRIVATE TERTIARY CARE CENTER IN GUWAHATI Baruah Melody. Healthcity Hospital Background:The COVID-19 pandemic affected millions of people with patients presenting with a constellation of symptoms and comorbidities. We aimed to estimate the extent of symptoms, comorbidities, other risk factors and outcome of COVID-19 cases presenting at our facility. Methods:Clinical and laboratory data was collected, including age, sex, comorbidities, tests performed for confirmation and outcome of 432 positive patients presenting to our tertiary care center from 1st July to 15th October 2020. This was an observational study. Patient outcomes were recorded as death, discharge and lost-to-follow up. Results:The most common age group of confirmed positives was 51-60 years, with 66% males. 78% presented with clinical symptoms, the most frequent being fever followed by cough. 82% of confirmed positive was detected by Trunat RT PCR, 3% by Rapid Antigen test and 15% by both these tests. The clinical outcome was: Discharged -73%, Death-6% and lost-to-follow-up -21%. However COVID19 was the cause of death in 1.1%. Among the discharged S74 patients 53% had comorbidities with Diabetes (34.1%) being the commonest. Comorbidities were present in 82.1% deceased patients, of which hypertension (42.8%) was most predominant. All the deceased patients presented with clinical symptoms of which breathlessness (53.5%) was most common. Conclusions:In this single-center study of 432 patients with confirmed COVID19, the characteristic findings included higher incidence in males, high proportion of symptomatic patients and association of comorbidities (hypertension and diabetes) with adverse outcome. We also found that Trunat RT PCR is far more reliable than Rapid Antigen test for COVID diagnosis. https://doi.org/10.1016/j.ijmmb.2021.08.255 COMPARABILITY OF THE SENSITIVITY OF DIFFERENT REAL TIME PCR KITS USED IN THE DETECTION OF SARS COV -2 Akshatha Ravindra, Baijayantimala Mishra, Sutapa Rath, Monalisa Mohanty, Jai Ranjan, Vinaykumar Hallur, Srujana Mohanty, Bijayini Behera, Ashoka Mahapatra. Department of Microbiology, AIIMS, Bhubaneswar Background:COVID-19 pandemic is posing a major burden on society. Measures taken to reduce its spread critically depend on timely and accurate identification of virus-infected individuals by the most sensitive and specific method available, i.e. real-time reverse transcriptase PCR (RT-PCR). RT PCR can detect SARS-CoV-2 as early as day one of symptom onset. There are various RT PCR kits approved by FDA & ICMR, performance of which vary widely. Here, we assessed the performance of four PCR kits with the ICMR NIV Screening & Confirmatory assay used for diagnosis of COVID -19 in Odisha. Methods:A total of 20 samples, which included five positives, one inconclusive& 14 negative samples by NIV assay were evaluated in the four commercially available RT-PCR kits ie; Q-line Molecular (Q-line), AllplexTM 2019-nCoV Assay (Allplex), Liferiver Novel Coronavirus (COVID-19) Multiplex RT PCR (Liferiver), LabGunTM COVID-19 kit (LabGun). Results:The sensitivity of the four PCR kits varied with the high cycle threshold (Ct) value (30-35 by NIV) & the lower Ct value (<30 by NIV). Among the negative results of NIV (n1⁄414), LabGun, Allplex kits showed 100% concordance, while Q line & Liferiver were shown to have 92.8% & 50% concordance respectively. In the inconclusive results (n1⁄41), only Allplex Assay documented a concordance of 100% with the NIV assay, while the Q -line (n1⁄46) & Liferiver (n1⁄47) showed higher number of inconclusive results. The different kits showed lesser variations with positive results (n1⁄45), with Liferiver, Allplex & LabGun showing 100% concordance for positive results with NIV assay. However, Q-line was able to detect only 1 positive out of all positives. Conclusions:PCR kits vary in sensitivity & it is imperial to evaluate the various kits in order to deliver accurate results at optimum time in order to detect the cases to initiate adequate treatment & control measures https://doi.org/10.1016/j.ijmmb.2021.08.256 PERFORMANCE ANALYSIS OF DIFFERENT REAL TIME-PCR KITS FOR THE DIAGNOSIS OF SARS-COV-2 VIRUS R.U.C.H.I. GANVIR, Rajeev Kumar Jain, P. Nagraj, Kamlesh Ahirwar, Jaya Lalwani. GANDHI MEDICAL COLLEGE, BHOPAL Background: At present the whole world is facing pandemic of the COVID-19 disease caused by SARS-CoV-2 virus. Rapid and correct laboratory diagnosis is indispensable to stop its spread and break the chain of transmission. In India, ICMR has approved numerous RT-PCR kits for the diagnosis of COVID-19 but an independent performance analysis of these kits is not done till date. We comparatively evaluated performance of ten COVID-19 RT-PCR kits and we conclude that all RT-PCR kits can be used for the routine diagnosis of COVID-19 patients. Methods:Performance analysis of the selected kits was done on the basis of number of target genes in the kit, labelled fluorophores, internal control, total RT-PCR run time, threshold cycle and result interpretation. Among all the