Longitudinal profile of antibody response to SARS-CoV-2 in patients with COVID-19 in a setting from Sub–Saharan Africa: A prospective longitudinal study

Abstract

Background Serological testing for SARS-CoV-2 plays an important role for epidemiological studies, in aiding the diagnosis of COVID-19, and assess vaccine responses. Little is known on dynamics of SARS-CoV-2 serology in African settings. Here, we aimed to characterize the longitudinal antibody response profile to SARS-CoV-2 in Ethiopia. Methods In this prospective study, a total of 102 PCR-confirmed COVID-19 patients were enrolled. We obtained 802 plasma samples collected serially. SARS-CoV-2 antibodies were determined using four lateral flow immune-assays (LFIAs), and an electrochemiluminescent immunoassay. We determined longitudinal antibody response to SARS-CoV-2 as well as seroconversion dynamics. Results Serological positivity rate ranged between 12%-91%, depending on timing after symptom onset. There was no difference in positivity rate between severe and non-severe COVID-19 cases. The specificity ranged between 90%-97%. Agreement between different assays ranged between 84%-92%. The estimated positive predictive value (PPV) for IgM or IgG in a scenario with seroprevalence at 5% varies from 33% to 58%. Nonetheless, when the population seroprevalence increases to 25% and 50%, there is a corresponding increases in the estimated PPVs. The estimated negative-predictive value (NPV) in a low seroprevalence scenario (5%) is high (>99%). However, the estimated NPV in a high seroprevalence scenario (50%) for IgM or IgG is reduced significantly to 80% to 85%. Overall, 28/102 (27.5%) seroconverted by one or more assays tested, within a median time of 11 (IQR: 9–15) days post symptom onset. The median seroconversion time among symptomatic cases tended to be shorter when compared to asymptomatic patients [9 (IQR: 6–11) vs. 15 (IQR: 13–21) days; p = 0.002]. Overall, seroconversion reached 100% 5.5 weeks after the onset of symptoms. Notably, of the remaining 74 COVID-19 patients included in the cohort, 64 (62.8%) were positive for antibody at the time of enrollment, and 10 (9.8%) patients failed to mount a detectable antibody response by any of the assays tested during follow-up. Conclusions Longitudinal assessment of antibody response in African COVID-19 patients revealed heterogeneous responses. This underscores the need for a comprehensive evaluation of seroassays before implementation. Factors associated with failure to seroconvert needs further research.

Seroprevalence of Natural and Acquired Immunity against the SARS-CoV-2 Virus in a Population Cohort from Two Chilean Cities, 2020–2022

“…Firstly, about 40% of the initial sample from 2020 participated in all three rounds of measurement of SARS-CoV-2 antibodies. However, the rate of loss to follow-up was within the range expected for this type of study [ 21 , 26 , 27 ], and, assuming that the loss is random, this issue would not affect the representativeness of the sample. In fact, the sample size is adequate for statistical power and the biodemographic characteristics of the original sample were maintained among those who continued across all three rounds [ 5 , 11 ].…”

“…However, the sequential measurement of the levels of antibodies in the same population sample, along with knowledge of the history of disease and vaccination, makes it easier to identify natural and acquired immunity and also helps to facilitate the identification of the factors associated with immunity. Indeed, hybrid seroprevalence follow-up studies have been carried out in various countries [ 10 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ].…”

Kinetics of naturally induced binding and neutralizing anti-SARS-CoV-2 antibody levels and potencies among Kenyan patients with diverse grades of COVID-19 severity

“…They used lateral flow immunoassays to quantify anti-spike and anti-nucleoprotein IgM, IgG, and an electro-chemiluminescent assay to quantify total anti-nucleoprotein immunoglobulins. They reported heterogenous antibody kinetics and a lack of sero-conversion among some patients (27). A South African study reported rapid waning of anti-SARS-CoV-2 RBD IgA and IgM, but a better maintenance of IgG antibodies quantified weekly over a period of 3 months among COVID-19 patients (55).…”

“…Together, such data suggests the existence of inter-population differences in people's abilities to generate and maintain anti-SARS-CoV-2 antibodies. However, there is a paucity of data on the kinetics and functions of anti-SARS-CoV-2 antibodies from Sub-Saharan African populations (25)(26)(27).…”

Pre-pandemic cross-reactive humoral immunity to SARS-CoV-2 in Africa: systematic review and meta-analysis

“…After screening 38 studies (Figure 1) and excluding 16 (Supplementary references), 22 studies were eligible (18 retrieved from the main search and another 4 retrieved from cited/citation searches). [3][4][5][6][7][8][9][10][11][12][13][14][22][23][24][25][26][27][28][29][30][31] 19 studies were published in peer-reviewed journals and 3 were preprints. Other studies screened in-depth and excluded are shown in Supplementary References along with the reason for exclusion.…”