Kinetics of specific anti-SARS-CoV-2 IgM, IgA, and IgG responses during the first 12 months after SARS-CoV-2 infection: A prospective longitudinal study

Abstract

Coronavirus 2019 (COVID-19) is a global health threat. The kinetics of antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) need to be assessed, as the long-term duration of these immunoglobulins remains largely controversial. The aim of this study was to assess the longitudinal dynamics of anti-SARS-CoV-2 antibodies against the nucleocapsid (N) protein and the receptor-binding domain (RBD) of the spike protein up to one year in a cohort of 190 COVID-19 patients. Between March and September 2021, we enrolled patients from two regional hospitals in Casablanca, Morocco. Blood samples were collected and analyzed for antibody levels. We used the commercial Euroimmun ELISA for the determination of anti-N IgM, the Abbott Architect™ SARS-CoV-2 IgG test for the detection of anti-RBD IgG, and an in-house kit for the assay of anti-N IgG and anti-N IgA. IgM and IgA antibodies were assessed 2–5, 9–12, 17–20 and 32–37 days after symptom onset. IgG antibodies were also assessed 60, 90, 120 and 360 days after symptom onset. One-third of patients developed IgM (32%), while two-thirds developed IgA (61%). One month of symptom onset, most patients developed IgG, with 97% and 93% positivity for anti-RBD IgG and anti-N IgG, respectively. The anti-RBD IgG positivity rate remained high up to one year of follow-up. However, the anti-N IgG positivity rate decreased over time, with only 41% of patients testing positive after one year’s follow-up. IgG levels were significantly higher in older people (over 50 years) than in other study participants. We also found that patients who had received two doses of ChAdOx1 nCoV-19 vaccine prior to infection had a lower IgM response than unvaccinated patients. This difference was statistically significant two weeks after the onset of symptoms. We present the first study in Africa to measure the kinetics of antibody response (IgA, IgM and IgG) to SARS-CoV-2 over one year. Most participants remained seropositive for anti-RBD IgG after one year but showed a significant decline in antibody titers.

Reduced control of SARS-CoV-2 infection associates with lower mucosal antibody responses in pregnancy

“…Although previous reports suggest that pregnant patients have reduced antibody responses to SARS-CoV-2 infection ( 5 , 16 – 18 ), these studies focused solely on serum antibody responses. As SARS-CoV-2 infection initiates in the upper respiratory tract, we sought to evaluate whether differences in mucosal IgG responses between non-pregnant and pregnant people may account for differences in clinical severity.…”

“…As SARS-CoV-2 infection initiates in the upper respiratory tract, we sought to evaluate whether differences in mucosal IgG responses between non-pregnant and pregnant people may account for differences in clinical severity. IgG was quantified rather than IgA because titers of IgG and seroconversion rates of IgG are higher in response to mRNA vaccines ( 17 , 19 – 22 ). Vaccinated individuals had greater anti-S IgG titers than unvaccinated individuals, regardless of pregnancy status ( P < 0.0001; Fig.…”

SARS-CoV-2 infection, inflammation and birth outcomes in a prospective NYC pregnancy cohort

“…This could have led to misclassification of the exposure. While the presence of IgG-type antibodies is a good indication that a person was exposed to the virus or vaccine ( Al-Tamimi et al, 2023 ; Amellal et al, 2023 ), in the absence of PCR results a combined analysis of more rapidly generated and degenerated IgM could have helped to determine whether participants were recently infected. Despite adjusting for multiple other covariates that might influence cytokines and HS-CRP levels, there may be unmeasured causes within individuals masking true association between SARS-CoV-2 infection and IL-1β, IL-6, IL-17A and HS-CRP levels.…”

Mapping IgA Epitope and Cross-Reactivity between Severe Acute Respiratory Syndrome-Associated Coronavirus 2 and DENV

“…Despite this, IgM molecules exhibit multipoint binding, increasing overall avidity. Subsequent immune responses also can yield some IgM production after somatic hypermutation, although other isotypes tend to dominate in the later stages of the antibody response [ 32 , 55 ]. Alternatively, the class switching can also result in the formation of IgA [ 32 ].…”

“…In this context, some lateral flow rapid tests, enzyme-linked immunosorbent assay (ELISA) kits, and IgA-based assays have been regarded as more sensitive yet less specific than IgG-based counterparts [ 32 , 33 ]. However, cross-reactivity has been detected with both tests [ 34 , 35 , 36 , 37 , 38 ].…”