Factors influencing the immune response over 15 months after SARS‐CoV‐2 infection: A longitudinal population‐wide study in the Faroe Islands

Abstract

Background The durability of SARS‐CoV‐2 antibody response and the resulting immunity to COVID‐19 is unclear. Objectives To investigate long‐term humoral immunity to SARS‐CoV‐2. Methods In this nationwide, longitudinal study, we determined antibody response in 411 patients aged 0–93 years from two waves of infections (March to December 2020) contributing 1063 blood samples. Each individual had blood drawn on 4–5 occasions 1–15 months after disease onset. We measured total anti‐SARS‐CoV‐2 receptor‐binding domain (RBD) antibody using a qualitative RBD sandwich ELISA, IgM, IgG and IgA levels using an quantitative in‐house ELISA‐based assay and neutralizing antibodies (NAbs) using an in‐house ELISA‐based pseudoneutralizing assay. IgG subclasses were analyzed in a subset of samples by ELISA‐based assay. We used nonlinear models to study the durability of SARS‐CoV‐2 antibody responses and its influence over time. Results After 15 months, 94% still had detectable circulating antibodies, mainly the IgG isotype, and 92% had detectable NAbs. The distribution of IgG antibodies varied significantly over time, characterized by a biphasic pattern with an initial decline followed by a plateau after approximately 7 months. However, the NAbs remained relatively stable throughout the period. The strength of the antibody response was influenced by smoking and hospitalization, with lower IgG levels in smokers and higher levels in hospitalized individuals. Antibody stability over time was mainly associated with male sex and older age with higher initial levels but more marked decrease. Conclusions The humoral immune response to SARS‐CoV‐2 infection varies depending on behavioral factors and disease severity, and antibody stability over 15 months was associated with sex and age.

Longitudinal study of humoral immunity against SARS-CoV-2 of health professionals in Brazil: the impact of booster dose and reinfection on antibody dynamics

“…Overall, we demonstrated that even after the booster dose, health professionals can become reinfected with new variants of SARS-CoV-2. Therefore, our study demonstrates that prolonged protection after COVID-19 infection, even after the booster dose, does not prevent reinfection by new variants, which contrasts with the prolonged immune response cited by other studies (66,80). Studies show that previous infection and booster dose reduce the risk of reinfection, as seen in Switzerland (81), Qatar (61), and United States of America (82).…”

“…Even though age was not associated with reinfection, we observed that the dynamics of antibody levels varied over time and behaved differently across age groups. The level of antibodies produced by the younger group was lower than the older groups, as observed by others works (66,72,73) Many studies have sought to understand and relate antibody profiles and Ct values with disease severity and protection against reinfection (27,33,74,75). Omid Dadras et al, 2022 (76), concluded that the relationship between viral load and disease severity is inconclusive.…”

“…Some studies show that men are more likely to test positive and develop severe COVID-19 (65). Petersen et al, (2022) (66) showed a faster decrease in IgG in males. Frauke et al (2022) (34)observed that the decline of neutralizing antibodies in men was faster than in women but that afterward, there was no difference in response.…”

Low levels of neutralizing antibodies against XBB Omicron subvariants after BA.5 infection

“…Previous study reported the circulating antibody levels in male were initial higher but more marked decrease. 38 However, our study only focused on the effects of sex factor on neutralizing antibodies in sera collected at 2–4 weeks after infection, the more information about the dynamics of humoral immunity should be investigated in future studies.…”

Factors associated with receipt of COVID-19 vaccination and SARS-CoV-2 seropositivity among healthcare workers in Albania (February 2021–June 2022): secondary analysis of a prospective cohort study

“…Alternatively, smokers may have avoided infection-prone settings due to awareness of their increased risk of severe disease. However, several studies have suggested that smoking is associated with overall reduced levels of IgA, IgG and IgM titers, and of IgG following SARS-CoV-2 infection or COVID-19 vaccination, 55 , 56 , 57 , 58 , 59 hence a lower seroprevalence among smokers could be an artefact.…”