SARS-CoV-2-infection- and vaccine-induced antibody responses are long lasting with an initial waning phase followed by a stabilization phase.

It is thought that mRNA-based vaccine-induced immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) wanes quickly, based mostly on short-term studies. Here, we analyzed the kinetics and durability of the humoral responses to SARS-CoV-2 infection and vaccination using >8,000 longitudinal samples collected over a 3-year period in New York City. Upon primary immunization, participants with pre-existing immunity mounted higher antibody responses faster and achieved higher steady-state antibody titers than naive individuals. Antibody kinetics were characterized by two phases: an initial rapid decay, followed by a stabilization phase with very slow decay. Booster vaccination equalized the differences in antibody concentration between participants with and without hybrid immunity, but the peak antibody titers decreased with each successive antigen exposure. Breakthrough infections increased antibodies to similar titers as an additional vaccine dose in naive individuals. Our study provides strong evidence that SARS-CoV-2 antibody responses are long lasting, with initial waning followed by stabilization.

Proteomic and Cellular Characterization of Omicron Breakthrough Infections and a Third Homologous or Heterologous Boosting Vaccination in a Longitudinal Cohort.

The understanding of dynamic plasma proteome features in hybrid immunity and breakthrough infection is limited. A deeper understanding of the immune differences between heterologous and homologous immunization could assist in the future establishment of vaccination strategies. In this study, 40 participants who received a third dose of either a homologous BBIBP-CorV or a heterologous ZF2001 protein subunit vaccine following two doses of inactivated coronavirus disease 2019 vaccines and 12 patients with BA2.2 breakthrough infections were enrolled. Serum samples were collected at days 0, 28, and 180 following the boosting vaccination and breakthrough and then analyzed using neutralizing antibody tests and mass spectrometer-based proteomics. Mass cytometry of peripheral blood mononuclear cell samples was also performed in this cohort. The chemokine signaling pathway and humoral response markers (IgG2 and IgG3) associated with infection were found to be upregulated in breakthrough infections compared to vaccination-induced immunity. Elevated expression of IGKV, IGHV, IL-17 signaling, and the phagocytosis pathway, along with lower expression of FGL2, were correlated with higher antibody levels in the boosting vaccination groups. The MAPK signaling pathway and Fc gamma R-mediated phagocytosis were more enriched in the heterologous immunization groups than in the homologous immunization groups. Breakthrough infections can trigger more intensive inflammatory chemokine responses than vaccination. T-cell and innate immune activation have been shown to be closely related to enhanced antibody levels after vaccination and therefore might be potential targets for vaccine adjuvant design.

Correlates of protection and determinants of SARS-CoV-2 breakthrough infections 1 year after third dose vaccination.

BACKGROUND: The emergence of new SARS-CoV-2 variants and the waning of immunity raise concerns about vaccine effectiveness and protection against COVID-19. While antibody response has been shown to correlate with the risk of infection with the original variant and earlier variants of concern, the effectiveness of antibody-mediated protection against Omicron and the factors associated with protection remain uncertain. METHODS: We evaluated antibody responses to SARS-CoV-2 spike (S) and nucleocapsid (N) antigens from Wuhan and variants of concern by Luminex and their role in preventing breakthrough infections 1 year after a third dose of mRNA vaccination, in a cohort of health care workers followed since the pandemic onset in Spain (N = 393). Data were analyzed in relation to COVID-19 history, demographic factors, comorbidities, vaccine doses, brand, and adverse events. RESULTS: Higher levels of anti-S IgG and IgA to Wuhan, Delta, and Omicron were associated with protection against vaccine breakthroughs (IgG against Omicron S antigen HR, 0.06, 95%CI, 0.26-0.01). Previous SARS-CoV-2 infection was positively associated with antibody levels and protection against breakthroughs, and a longer time since last infection was associated with lower protection. In addition, priming with BNT162b2 followed by mRNA-1273 booster was associated with higher antibody responses than homologous mRNA-1273 vaccination. CONCLUSIONS: Data show that IgG and IgA induced by vaccines against the original strain or by hybrid immunization are valid correlates of protection against Omicron BA.1 despite immune escape and support the benefits of heterologous vaccination regimens to enhance antibodies and the prioritization of booster vaccination in individuals without recent infections.

Epidemiology, clinical features and outcomes of hospitalized patients with COVID-19 by vaccination status: a multicenter historical cohort study.

INTRODUCTION: COVID-19 disease resulted in over six million deaths worldwide. Although vaccines against SARS-CoV-2 demonstrated efficacy, breakthrough infections became increasingly common. There is still a lack of data regarding the severity and outcomes of COVID-19 among vaccinated compared to unvaccinated individuals. METHODS: This was a historical cohort study of adult COVID-19 patients hospitalized in five Ascension hospitals in southeast Michigan. Electronic medical records were reviewed. Vaccine information was collected from the Michigan Care Improvement Registry. Data were analyzed using Student's t-test, analysis of variance, the chi-squared test, the Mann-Whitney and Kruskal-Wallis tests, and multivariable logistic regression. RESULTS: Of 341 patients, the mean age was 57.9 ± 18.3 years, 54.8% (187/341) were female, and 48.7% (166/341) were black/African American. Most patients were unvaccinated, 65.7%, 8.5%, and 25.8% receiving one dose or at least two doses, respectively. Unvaccinated patients were younger than fully vaccinated (p = 0.001) and were more likely to be black/African American (p = 0.002). Fully vaccinated patients were 5.3 times less likely to have severe/critical disease (WHO classification) than unvaccinated patients (p < 0.001) after controlling for age, BMI, race, home steroid use, and serum albumin levels on admission. The case fatality rate in fully vaccinated patients was 3.4% compared to 17.9% in unvaccinated patients (p = 0.003). Unvaccinated patients also had higher rates of complications. CONCLUSIONS: Patients who were unvaccinated or partially vaccinated had more in-hospital complications, severe disease, and death as compared to fully vaccinated patients. Factors associated with severe COVID-19 disease included advanced age, obesity, low serum albumin, and home steroid use.

Protective role of SARS-CoV-2 anti-S IgG against breakthrough infections among European healthcare workers during pre and post-Omicron surge-ORCHESTRA project.

PURPOSE: Anti SARS-CoV-2 vaccination initially showed high effectiveness in preventing COVID-19. However, after the surge of variants of concern, the effectiveness dropped. Several studies investigated if this was related to the decrease of the humoral response over time; however, this issue is still unclear. The aim of this study was to understand whether SARS-CoV-2 anti-S IgG levels can be used to predict breakthrough infection risk and define the timing for further booster doses administration. METHOD: Within the framework of the ORCHESTRA Project, over 20,000 health workers from 11 European centers were enrolled since December 2020. We performed two Cox proportional hazards survival analyses regarding pre-Omicron (from January to July 2021) and Omicron (December 2021-May 2022) periods. The serological response was classified as high (above the 75th percentile), medium (25th-75th), or low (< 25th). RESULTS: Seventy-four (0.33%) and 2122 (20%) health workers were infected during the first and second periods, respectively. Both Cox analyses showed that having high anti-S titer was linked to a significantly lower risk of infection as compared to having medium serological response [HR of high vs medium anti-S titer = 0.27 (95% CI 0.11-0.66) during the first phase, HR = 0.76 (95% CI 0.62-0.93) during the second phase]. CONCLUSION: Vaccine effectiveness wanes significantly after new variants surge, making anti-S titer unsuitable to predict optimal timing for further booster dose administration. Studies on other immunological indicators, such as cellular immunity, are therefore needed to better understand the mechanisms and duration of protection against breakthrough infection risk.

Effects of antivirals on patients with COVID-19 breakthrough.

BACKGROUND: Antivirals have been given widely for patients with COVID-19 breakthrough in Asian countries, creating a "black market" for unapproved and unprescribed medications. More evidence is needed to clarify the benefits of antivirals in these settings. METHODS: We conducted a random-sampling retrospective cohort study at a general hospital in Vietnam. We recruited patients with mild-to-moderate COVID-19 breakthrough who were given either standard of care (SoC) alone or SoC + antiviral. Primary outcome was residual respiratory symptoms that lasted > 7 days. Secondary outcome was long COVID-19, diagnosed by specialized physicians. We used logistic regression to measure odds ratio (OR), in addition to a sensitivity and subgroup analyses to further explore the results. RESULTS: A total of 142 patients (mean age 36.2 ± 9.8) were followed. We recorded residual symptoms in 27.9% and 20.3% of the SoC and SoC + antiviral group, while the figures for long COVID-19 were 11.8% and 8.1%, respectively. Antiviral use was not significantly associated with lower the risks of residual symptoms (OR = 0.51, 95% CI: 0.22-1.20, p = 0.12) or long COVID-19 (OR = 0.55, 95% CI: 0.16-1.90, p = 0.35). The sensitivity and subgroup analyses did not show any significant differences between the study groups (all p > 0.05). CONCLUSION: Antivirals were not associated with faster resolution of respiratory symptoms or lower risks of long COVID-19. Further studies should focus on different antivirals to confirm their effects on different sub-populations. Meanwhile, antivirals should only be used in very high-risk patients to avoid excessive costs and harms.

Correlates of breakthrough COVID-19 in vaccinated patients with systemic sclerosis: survival analysis from a multicentre international patient-reported survey.

This study aimed to assess the incidence, predictors, and outcomes of breakthrough infection (BI) following coronavirus disease (COVID-19) vaccination in patients with systemic sclerosis (SSc), a risk group associated with an immune-suppressed state and high cardiopulmonary disease burden. Cross-sectional data from fully vaccinated respondents with SSc, non-SSc autoimmune rheumatic diseases (AIRDs), and healthy controls (HCs) were extracted from the COVAD database, an international self-reported online survey. BI was defined according to the Centre for Disease Control definition. Infection-free survival was compared between the groups using Kaplan-Meier curves with log-rank tests. Cox proportional regression was used to assess the association between BI and age, sex, ethnicity, and immunosuppressive drugs at the time of vaccination. The severity of BI in terms of hospitalization and requirement for oxygen supplementation was compared between groups. Of 10,900 respondents, 6836 fulfilled the following inclusion criteria: 427 SSc, 2934 other AIRDs, and 3475 HCs. BI were reported in 6.3% of SSc, 6.9% of non-SSc AIRD, and 16.1% of HCs during a median follow-up of 100 (IQR: 60-137) days. SSc had a lower risk for BI than HC [hazard ratio (HR): 0.56 (95% CI 0.46-0.74)]. BIs were associated with age [HR: 0.98 (0.97-0.98)] but not ethnicity or immunosuppressive drugs at the time of vaccination. Patients with SSc were more likely to have asymptomatic COVID-19, but symptomatic patients reported more breathlessness. Hospitalization [SSc: 4 (14.8%), HCs: 37 (6.6%), non-SSc AIRDs: 32(15.8%)] and the need for oxygenation [SSc: 1 (25%); HC: 17 (45.9%); non-SSc AIRD: 13 (40.6%)] were similar between the groups. The incidence of BI in SSc was lower than that in HCs but comparable to that in non-SSc AIRDs. The severity of BI did not differ between the groups. Advancing age, but not ethnicity or immunosuppressive medication use, was associated with BIs.

COVID-19 breakthrough infections in type 1 diabetes mellitus: a cross-sectional study by the COVID-19 Vaccination in Autoimmune Diseases (COVAD) Group.

To investigate the frequency, profile, and severity of COVID-19 breakthrough infections (BI) in patients with type I diabetes mellitus (T1DM) compared to healthy controls (HC) after vaccination. The second COVID-19 Vaccination in Autoimmune Diseases (COVAD-2) survey is a multinational cross-sectional electronic survey which has collected data on patients suffering from various autoimmune diseases including T1DM. We performed a subgroup analysis on this cohort to investigate COVID-19 BI characteristics in patients with T1DM. Logistic regression with propensity score matching analysis was performed. A total of 9595 individuals were included in the analysis, with 100 patients having T1DM. Among the fully vaccinated cohort, 16 (16%) T1DM patients had one BI and 2 (2%) had two BIs. No morbidities or deaths were reported, except for one patient who required hospitalization with oxygen without admission to intensive care. The frequency, clinical features, and severity of BIs were not significantly different between T1DM patients and HCs after adjustment for confounding factors. Our study did not show any statistically significant differences in the frequency, symptoms, duration, or critical care requirements between T1DM and HCs after COVID-19 vaccination. Further research is needed to identify factors associated with inadequate vaccine response in patients with BIs, especially in patients with autoimmune diseases.

SARS-CoV-2 vaccine breakthrough infection and the evaluation of safety precaution practice before and after vaccination among healthcare workers in South West, Nigeria.

INTRODUCTION: Worldwide, it has been reported that fully vaccinated people still die of COVID-19-associated symptoms, generating public uncertainty about the safety and effectiveness of the vaccines. Hence, this research is aimed at assessing the incidence of COVID-19 breakthrough infection among vaccinated Health Workers and the possible effect of changes in the practice of post-vaccination safety precautions. METHOD: This was a Health facility-based descriptive cross-sectional study. Data were collected using self-administered questionnaires distributed at the participant's work unit across the selected health facilities. The nasopharyngeal specimen was also obtained from the participants and analysed using STANDARD Q COVID-19 Ag Test rapid chromatographic immunoassay for the detection of antigens to SARS-CoV-2. All data were input and analyzed using SPSS version 20. RESULTS: There was a statistically significant relationship between the vaccination status of respondents and the post-vaccination test result (χ2 = 6.816, df = 1, p = 0.009). The incidence of COVID-19 infection among the vaccinated and unvaccinated HCWs was 2% and 8% respectively. 5 of the 15 respondents who tested positive for COVID-19 had been fully vaccinated. However, all 5 of them did not practice safety measures after vaccination. None of the respondents who practised safety measures after vaccination tested positive for COVID-19. The remaining 10 respondents that tested positive for COVID-19 had not been vaccinated though they practised safety precautions. CONCLUSION: Vaccination and the practice of safety precautions will go a long way to preventing future COVID-19 breakthrough infections.

Adapting response to a measles outbreak in a context of high vaccination and breakthrough cases: an example from Vaud, Switzerland, January to March 2024.

A measles outbreak with 51 cases occurred in the canton of Vaud, Switzerland, between January and March 2024. The outbreak was triggered by an imported case, and 37 (72.5%) subsequent cases were previously vaccinated individuals. Epidemiological investigations showed that vaccinated measles cases were symptomatic and infectious. In a highly vaccinated population, it is important to raise awareness among healthcare professionals to suspect and test for measles virus when an outbreak is declared, irrespective of the vaccination status of the patients.