Shedding of SARS COV-2 virus in COVID-19 patients and neutralizing antibody levels

INTRODUCTION AND AIM: In this study, it was aimed to investigate the presence of SARS CoV-2 RNA in various clinical samples taken from COVID-19 patients, the shedding profile of the virus, and the anti-SARS CoV-2 IgG and neutralizing antibody responses in infected patients. METHODS: 47 COVID-19 patients from the community (CCP, May-June 2020) and 30 healthcare worker COVID-19 patients (HCWP, November-December 2020) were included in the study. Oropharynx, nasopharynx, sputum, blood, stool and urine samples were taken from the CCP group on days 0, 3, 7, 14 and 28 to investigate SARS CoV-2 RNA. Serum samples were taken from CCP and HCWP groups on consecutive days for the determination of anti SARS CoV-2 IgG and neutralizing antibodies (NAb). RNA of the virus; RT-PCR, anti-SARS CoV-2 IgG antibody levels; ELISA, NAb levels; determined by cell culture and surrogate neutralization test methods. RESULTS: SARS CoV-2 had the highest rates in the nasopharynx (100%), stool (65.8%), sputum (45.7%), oropharynx (41.3%), blood (5.3%), and urine, respectively. It was detected in (2.2%) samples. It was observed that viral shedding continued for 14 days in respiratory tract samples and up to 60 days in stool samples, and no virus was detected in blood samples after the 3rd day. It was observed that the viral load was at the highest level at the time of diagnosis in respiratory tract samples, and peaked on the 7th day in stool samples. At the fourth month, IgG positivity was found in all CCP group patients, and seropositivity was found in only 82.1% of HWCP group patients. At the end of the first month, NAb was detected in all (100%) patients in the CCP group. In CCP group patients, NAb titers peaked on the 28th day and then decreased. It was determined that 26.1% of the patients in the HCWP group had low, 47.8% moderate and 26.1% high titers of surrogate NAb. CONCLUSION: As a result; SARS CoV-2 RNA was detected in many samples such as sputum, stool, blood and urine, and it was observed that viral shedding in stool samples could continue for months. Anti-SARS CoV-2 IgG antibody positivity was observed in most of the patients at the 4th month. It was determined that protective antibody levels reached the highest level in the first month of the disease. These findings are important in vaccination strategies and in the fight against the pandemic. However, more detailed and comprehensive studies are needed for virus scattering and antibody titer studies.