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Background: COVID-19 caused by SARS-CoV-2 ranges from asymptomatic to severe disease and can cause fatal and devastating outcome in many cases. In this study, we have compared the clinical, biochemical and immunological parameters across the different disease spectrum of COVID-19 in Bangladeshi patients. Methodology/Principal findings: This longitudinal study was conducted in two COVID-19 hospitals and also around the community in Dhaka city in Bangladesh between November 2020 to March 2021. A total of 100 patients with COVID-19 infection were enrolled and classified into asymptomatic, mild, moderate and severe cases (n = 25/group). In addition, thirty age and sex matched healthy participants were enrolled and 21 were analyzed as controls based on exclusion criteria. After enrollment (study day1), follow-up visits were conducted on day 7, 14 and 28 for the cases. Older age, male gender and co-morbid conditions were the risk factors for severe COVID-19 disease. Those with moderate and severe cases of infection had low lymphocyte counts, high neutrophil counts along with a higher neutrophil-lymphocyte ratio (NLR) at enrollment; this decreased to normal range within 42 days after the onset of symptom. At enrollment, D-dimer, CRP and ferritin levels were elevated among moderate and severe cases. The mild, moderate, and severe cases were seropositive for IgG antibody by day 14 after enrollment. Moderate and severe cases showed significantly higher IgM and IgG levels of antibodies to SARS-CoV-2 compared to mild and asymptomatic cases. Conclusion/Significance: We report on the clinical, biochemical, and hematological parameters associated with the different severity of COVID-19 infection. We also show different profile of antibody response against SARS-CoV-2 in relation to disease severity, especially in those with moderate and severe disease manifestations compared to the mild and asymptomatic infection. Author summary: In Bangladesh, very little is known about disease characteristics and serological responses in different spectrum of COVID-19 disease in patients. The risk factors responsible for causing severe COVID-19 illness, as well as data on clinical, biochemical and immunological parameters is still lacking or insufficient across different geographical regions for the prediction of the disease outcomes. This is the first longitudinal study in Bangladesh to evaluate the data on clinical, hematological parameters, viral load and antibody responses in COVID-19 infected asymptomatic, mild, moderate, and severe patients. Our study showed that older age, male gender, multiple co-morbid conditions and elevated NLR, D-dimer, ferritin and CRP levels can help clinicians to predict progression to more severe outcomes. Patients with moderate and severe disease developed higher levels of IgM and IgG antibodies to the receptor binding domain (RBD) of the spike protein of SARS-CoV-2 compared to patients suffering from mild disease or those with asymptomatic infections. However, all infected individuals developed antibody responses that were higher than that seen in healthy controls. [ABSTRACT FROM AUTHOR]

• The viral load in hepatitis E virus (HEV) infection is higher in the acute phases of jaundice. • As the HEV IgG response develops, the viral load starts to decline during the course of disease. • Pregnancy seems to modulate this response, keeping a high viral load for a longer period. • A higher viral load is associated with a lower IgG response in HEV-infected pregnant women. • Pregnancy seems to be associated with poorer disease outcomes for acute HEV hepatitis. To determine IgG immune responses and hepatitis E virus (HEV) viral load, and to explore the associations with pregnancy. A total of 121 HEV-infected women (57 pregnant, 64 non-pregnant) were analysed. Quantitative reverse transcription PCR (RT-qPCR) was done for 78 HEV IgM-positive patients to determine viral load, and Sanger sequencing was performed for 62 HEV-RNA-positive patients to confirm genotyping. ELISA was conducted to determine HEV antibody and avidity indices. The HEV genotype was identified as variant 1. Significant negative correlations were observed between log HEV copy number and log hepatitis E virus IgG antibody index in the late acute phase of jaundice for both pregnant women (r = −0.7971, p = 0.0002) and non-pregnant women (r = −0.9117, p = 0.0002). Pregnant women had significantly higher serum log viral copy numbers and lower IgG antibody indices than non-pregnant women in the late acute phase of HEV-induced jaundice (p = 0.0196 and p = 0.0303, respectively). Moreover, pregnant women with acute HEV hepatitis had higher cross-reactive IgG antibodies compared to the non-pregnant women (p = 0.0017). Five patients with HEV hepatitis died, of whom four were pregnant. Pregnancy might be associated with higher viral loads and a lower IgG response in the HEV-induced late acute phase of jaundice. [ABSTRACT FROM AUTHOR]