Longitudinal Serology of SARS-CoV-2-Infected Individuals in India: A Prospective Cohort Study

Abstract

Clinical and epidemiological characteristics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are now widely available, but there are few data regarding longitudinal serology in large cohorts, particularly those from low-income and middle-income countries. We established an ongoing prospective cohort of 3,840 SARS-CoV-2-positive individuals according to RT-PCR in the Delhi-National Capital Region of India to document clinical and immunological characteristics during illness and convalescence. The immunoglobulin G (IgG) responses to the receptor binding domain (RBD) and nucleocapsid were assessed at 0 to 7 days, 10 to 28 days, and 6 to 10 weeks after infection. The clinical predictors of seroconversion were identified by multivariable regression analysis. The seroconversion rates during the postinfection windows of 0 to 7 days, 10 to 28 days, and 6 to 10 weeks were 46%, 84.7%, and 85.3%, respectively ( N = 743). The proportion with a serological response increased with the severity of coronavirus disease 2019 (COVID-19). All participants with severe disease, 89.6% with mild to moderate infection, and 77.3% of asymptomatic participants had IgG antibodies to the RBD antigen. The threshold values for the nasopharyngeal viral RNA RT-PCR of a subset of asymptomatic and symptomatic seroconverters were comparable ( P = 0.48) to those of nonseroconverters ( P = 0.16) ( N = 169). This is the first report of longitudinal humoral immune responses to SARS-CoV-2 over a period of 10 weeks in South Asia. The low seropositivity of asymptomatic participants and differences between assays highlight the importance of contextualizing the understanding of population serosurveys.

SARS-CoV-2 Seroprevalence in Individuals With Type 1 and Type 2 Diabetes Compared With Controls

“…These women were exposed to hyperglycemia in the past, and remain at a high risk of future diabetes, however, they did not meet the criteria for diabetes in the present assessment. Rapid decay of antibody response and lower seroprevalence rates have been reported in patients with mild/asymptomatic infection [ 42 , 43 ]. The seroprevalence data reported in our study could therefore be an underestimate.…”

Nucleocapsid and spike antibody responses post virologically confirmed SARS-CoV-2 infection: An observational analysis in the Virus Watch community cohort

“…Although this is lower than other studies, where seroconversion rates have been 84.7% at 10-28 days respectively, these studies followed individuals who had been hospitalised due to COVID19. 17 When hospitalised individuals were stratified by symptom severity, the cumulative percentage of anti-N positive asymptomatic individuals was 60% at 22-28 days. 17 Other studies in hospitalised individuals have also demonstrated symptom severity is associated with an earlier peak in anti-N titres, as well as determining longer duration of anti-N positivity.…”

“…17 When hospitalised individuals were stratified by symptom severity, the cumulative percentage of anti-N positive asymptomatic individuals was 60% at 22-28 days. 17 Other studies in hospitalised individuals have also demonstrated symptom severity is associated with an earlier peak in anti-N titres, as well as determining longer duration of anti-N positivity. 22,23 Difference in anti-N over time was seen when the data was disaggregated by sex, with earlier peak and waning in females.…”

“…Previous studies have found that anti-N positivity after PCR confirmed infection ranges from 84.7% at 28 days to 68.2% at 293 days, with proportions being highest among those with severe symptom profiles. 17,18 Antibody positivity may be influenced by the viral load during infection, with higher viral loads causing higher levels of antigen exposure and more severe symptoms. 19 As our data is from a community cohort study it can be assumed that the symptom profiles may be less severe among our participants in comparison to hospital based longitudinal studies, and therefore leading to lower antibody levels.…”

Long-term Durable Humoral Immune Response to Heterologous Antigenic Exposure Post six months by Natural SARS-CoV-2 Infection and Vaccination

“…Others and we have shown that antibody levels wane over time. [1][2][3] Antigenic exposure through both vaccination and natural infection may act synergistically to boost immune responses. 4 There is a need for an evidence-driven booster vaccination policy depending on durability of immune response.…”