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1.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-337634

ABSTRACT

Population-level immunity to SARS-CoV-2 is growing through vaccination as well as ongoing circulation. Given waning immunity and emergence of new variants, it is important to dynamically determine the risk of re-infection in the population. For estimating immune protection, neutralization titers are most informative, but these assays are difficult to conduct at a population level. Measurement of antibody levels can be implemented at high throughput, but has not been robustly validated as a correlate of protection. Here, we have developed a method that predicts neutralization and protection based on variant-specific antibody measurements to SARS-CoV-2 antigens. This approach allowed us to estimate population-immunity in a longitudinal cohort from France followed for up to 2 years. Participants with a single vaccination or immunity caused by infection only are especially vulnerable to COVID-19 or hospitalization due to SARS-CoV-2. While the median reduced risk to COVID-19 in participants with 3 vaccinations was 96%, the median reduced risk among participants with infection-acquired immunity only was 42%. The results presented here are consistent with data from vaccine-effectiveness studies indicating robustness of our approach. Our multiplex serological assay can be readily optimized and employed to study any new variant and provides a framework for development of an assay that would include protection estimates.

2.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-331294

ABSTRACT

Background: The protective immunity against Omicron following a BNT162b2 Pfizer booster dose among elderly is not well characterized. Methods: Thirty-eight residents from three nursing homes were recruited for the study. Antibodies targeting the Spike protein of SARS-CoV-2 were measured with the S-Flow assay. Neutralizing activities in sera were measured as effective dilution 50% (ED50) with the S-Fuse assay using authentic isolates of Delta and Omicron. Results: Among the 38 elderly included in the study, with median (inter-quartile range, IQR) age of 88 (81-92) years, 30 (78.9%) had been previously infected. The ED50 of neutralization were lower against Omicron than Delta, and higher among convalescent compared to naive residents. During an Omicron epidemic affecting two of the three nursing homes in December 2021-January 2022, 75% (6/8) of naive residents got infected, compared to 25% (6/24) of convalescents (P=0.03). Antibody levels to Spike and ED50 of neutralization against Omicron after the BNT162b2 booster dose were lower in those with breakthrough infection (n=12) compared to those without (n=20): median of 1256 vs 2523 BAU/mL (P=0.02) and median ED50 of 234 vs 1298 (P=0.0004), respectively. Conclusion: This study confirmed the importance of receiving at least three antigenic exposures to the SARS-CoV-2 Spike protein for achieving satisfactory neutralizing antibody levels. In this population, protection against Omicron infection was increased in individuals who had been previously infected in addition to the three vaccine doses. Thus, a fourth antigenic exposure may be useful in the elderly population to prevent infection with Omicron, a variant known for its high escape immunity properties.

3.
J Infect Dis ; 224(9): 1489-1499, 2021 11 16.
Article in English | MEDLINE | ID: covidwho-1522216

ABSTRACT

BACKGROUND: Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces a complex antibody response that varies by orders of magnitude between individuals and over time. METHODS: We developed a multiplex serological test for measuring antibodies to 5 SARS-CoV-2 antigens and the spike proteins of seasonal coronaviruses. We measured antibody responses in cohorts of hospitalized patients and healthcare workers followed for up to 11 months after symptoms. A mathematical model of antibody kinetics was used to quantify the duration of antibody responses. Antibody response data were used to train algorithms for estimating time since infection. RESULTS: One year after symptoms, we estimate that 36% (95% range, 11%-94%) of anti-Spike immunoglobulin G (IgG) remains, 31% (95% range, 9%-89%) anti-RBD IgG remains, and 7% (1%-31%) of anti-nucleocapsid IgG remains. The multiplex assay classified previous infections into time intervals of 0-3 months, 3-6 months, and 6-12 months. This method was validated using data from a seroprevalence survey in France, demonstrating that historical SARS-CoV-2 transmission can be reconstructed using samples from a single survey. CONCLUSIONS: In addition to diagnosing previous SARS-CoV-2 infection, multiplex serological assays can estimate the time since infection, which can be used to reconstruct past epidemics.


Subject(s)
Antibodies, Viral/blood , COVID-19/blood , COVID-19/immunology , Serologic Tests/methods , Adolescent , Adult , Aged , Aged, 80 and over , Antibody Formation , Antibody Specificity , COVID-19/epidemiology , Female , France/epidemiology , Humans , Immunoglobulin G/blood , Kinetics , Male , Middle Aged , SARS-CoV-2/immunology , Sensitivity and Specificity , Seroepidemiologic Studies , Young Adult
4.
J Infect Dis ; 224(9): 1489-1499, 2021 11 16.
Article in English | MEDLINE | ID: covidwho-1317919

ABSTRACT

BACKGROUND: Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces a complex antibody response that varies by orders of magnitude between individuals and over time. METHODS: We developed a multiplex serological test for measuring antibodies to 5 SARS-CoV-2 antigens and the spike proteins of seasonal coronaviruses. We measured antibody responses in cohorts of hospitalized patients and healthcare workers followed for up to 11 months after symptoms. A mathematical model of antibody kinetics was used to quantify the duration of antibody responses. Antibody response data were used to train algorithms for estimating time since infection. RESULTS: One year after symptoms, we estimate that 36% (95% range, 11%-94%) of anti-Spike immunoglobulin G (IgG) remains, 31% (95% range, 9%-89%) anti-RBD IgG remains, and 7% (1%-31%) of anti-nucleocapsid IgG remains. The multiplex assay classified previous infections into time intervals of 0-3 months, 3-6 months, and 6-12 months. This method was validated using data from a seroprevalence survey in France, demonstrating that historical SARS-CoV-2 transmission can be reconstructed using samples from a single survey. CONCLUSIONS: In addition to diagnosing previous SARS-CoV-2 infection, multiplex serological assays can estimate the time since infection, which can be used to reconstruct past epidemics.


Subject(s)
Antibodies, Viral/blood , COVID-19/blood , COVID-19/immunology , Serologic Tests/methods , Adolescent , Adult , Aged , Aged, 80 and over , Antibody Formation , Antibody Specificity , COVID-19/epidemiology , Female , France/epidemiology , Humans , Immunoglobulin G/blood , Kinetics , Male , Middle Aged , SARS-CoV-2/immunology , Sensitivity and Specificity , Seroepidemiologic Studies , Young Adult
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