First Case of HIV Seroconversion With Integrase Resistance Mutations on Long-Acting Cabotegravir for Prevention in Routine Care.

Background: Long-acting cabotegravir (CAB-LA) is highly effective for HIV prevention, but delayed HIV diagnoses and integrase strand transfer inhibitor (INSTI) resistance were observed in trials. We report the first case in routine clinical care of HIV infection on CAB-LA with INSTI resistance. Methods: The SeroPrEP study enrolls individuals in the United States who acquire HIV on pre-exposure prophylaxis modalities to assess diagnostics, antiretroviral (ARV) drug levels, resistance, and treatment outcomes. Resistance mutations in full-length HIV-1 integrase were identified by single-genome sequencing (SGS). Cabotegravir concentrations in plasma and hair segments were measured by liquid chromatography-tandem mass spectrometry. Results: A 23-year-old gender-nonbinary person, male at birth, restarted CAB-LA 6 months after discontinuation due to losing insurance. Prior to restart, HIV-1 RNA was not detected, but 20 days elapsed before CAB-LA injection. After the second CAB-LA injection, HIV antigen/antibody returned reactive (HIV-1 RNA 451 copies/mL). SGS of plasma HIV-1 RNA identified INSTI mutation Q148R in 2/24 sequences 2 days postdiagnosis; commercial genotype failed amplification. Cabotegravir hair concentration was 0.190 ng/mg 2 weeks prediagnosis; plasma cabotegravir was high (3.37 µg/mL; ∼20× PA-IC90) 14 days postdiagnosis. Viral suppression was maintained for 6 months on darunavir/cobicistat/emtricitabine/tenofovir alafenamide, then switched to doravirine + emtricitabine/tenofovir alafenamide due to nausea. Conclusions: In this first case of HIV infection on CAB-LA with INSTI resistance in routine care, cabotegravir resistance was detected only with a sensitive research assay. Accelerated pathways to minimize time between HIV testing and CAB-LA initiation are needed to optimize acute HIV detection and mitigate resistance risk. Sustained product access regardless of insurance is imperative to reduce HIV infections on CAB-LA.

Breakthrough SARS-CoV-2 infection in fully vaccinated patients with systemic lupus erythematosus: results from the COVID-19 Vaccination in Autoimmune Disease (COVAD) study.

OBJECTIVE: To determine the occurrence of breakthrough COVID-19 infections (BIs) in patients with systemic lupus erythematosus (SLE) compared with patients with other rheumatic autoimmune diseases (rAIDs), patients with non-rheumatic autoimmune diseases (nrAIDs), and healthy controls (HCs). METHODS: The study was based on data from 7035 fully vaccinated respondents to the online COVAD questionnaire with SLE (N = 852), rAIDs (N = 3098), or nrAIDs (N = 414), and HCs (N = 2671). BI was defined as COVID-19 infection occurring in individuals vaccinated with ≥ 2 doses (or 1 dose of J&J) ≥ 14 days after vaccination and not after 6 months since the last vaccine dose. Data were analysed using linear and logistic regression models. RESULTS: A total of 91/852 (10.7%) SLE patients reported at least one BI. The frequency of BIs in SLE patients was comparable to that among HCs (277/2671; p = 0.847) and patients with nrAID (39/414; p = 0.552) but higher than that among patients with other rAIDs (235/3098; p = 0.005). No demographic factors or treatments were associated with BIs in SLE patients (p ≥ 0.05 for all). Joint pain was more frequent in SLE patients than in HCs (odds ratio [OR]: 3.38; 95% confidence interval [CI]: 1.89-6.04; p < 0.001) or nrAID patients (OR: 2.44; 95% CI: 1.04-5.75; p = 0.041). Patient with SLE did not report a higher frequency of hospitalisation or need for advanced treatment for COVID-19 infection compared with disease controls and HCs, respectively. CONCLUSION: COVID-19 vaccination conferred similar protection against COVID-19 infection in terms of frequency and severity in patients with SLE to that reported by healthy individuals.

SARS-CoV-2 reinfection broadens the antibody responses and promotes the phenotypic differentiation of virus-specific memory T cells in adolescents.

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron subvariants raises concerns regarding the effectiveness of immunity acquired from previous Omicron subvariants breakthrough infections (BTIs) or reinfections (RIs) against the current circulating Omicron subvariants. In this study, we prospectively investigate the dynamic changes of virus-specific antibody and T cell responses among 77 adolescents following Omicron BA.2.3 BTI with or without subsequent Omicron BA.5 RI. Notably, the neutralizing antibodies (NAbs) titers against various detected SARS-CoV-2 variants, especially the emerging Omicron CH.1.1, XBB.1.5, XBB.1.16, EG.5.1, and JN.1 subvariants, exhibited a significant decrease along the time. A lower level of IgG and NAbs titers post-BTI was found to be closely associated with subsequent RI. Elevated NAbs levels and shortened antigenic distances were observed following Omicron BA.5 RI. Robust T cell responses against both Omicron BA.2- and CH.1.1-spike peptides were observed at each point visited. The exposure to Omicron BA.5 promoted phenotypic differentiation of virus-specific memory T cells, even among the non-seroconversion adolescents. Therefore, updated vaccines are needed to provide effective protection against newly emerging SARS-CoV-2 variants among adolescents.

COVID-19 Vaccines Breakthrough Infections and Adverse Effects Reported by the Birzeit University Community in Palestine.

Background: Coronavirus disease (COVID-19) vaccines play an essential role in boosting immunity, preventing severe diseases, and alleviating the Covid-19 health crisis. Objective: This study aimed to explore the type and severity of short-term adverse reactions associated with BNT162 (Pfizer-BioNTech), mRNA 1273 (Moderna), and viral vector vaccines and to compare the incidence of post-vaccination Covid-19 infection among the Birzeit University community in Palestine. Methods: This questionnaire-based retrospective cross-sectional study was conducted among individuals who were vaccinated with at least one dose of any COVID-19 vaccine offered in Palestine during the COVID-19 pandemic. The study included participants aged 18 years and older who were vaccinated with Pfizer, Moderna, Sputnik Light, or Sputnik v. Results: A total of 558 participants who were administered COVID-19 vaccine were included in the study. Sputnik (239), Pfizer vaccine recipients (236), and Moderna vaccine recipients (83). Of the viral vector vaccine recipients, 57 (23.8%) had a post-vaccination infection, compared to 30 (12.7%) for Pfizer and seven (8.4%) for Moderna. Furthermore, the reported adverse effects in the viral victor group were higher than those in the Moderna and Pfizer groups (71.7, 66.3, and 61.9%, respectively). Chills, headache, fatigue, abdominal pain, and joint pain were significantly higher in the Viral Vector vaccine group than the Moderna and Pfizer vaccine. Vomiting, tiredness, and fatigue were significantly less likely to be complained of by Pfizer vaccine recipients compared to Moderna and Viral Vector vaccine recipients (p < 0.05). Conclusions: Breakthrough infections were associated with both viral vectors and mRNA; however, the mRNA vaccine had less reported post-vaccine infection. Furthermore, the Pfizer/BioNTech COVID-19 vaccine group reported fewer commonly reported side effects (fever, chills, headache, fatigue, muscle pain, joint pain, nausea, and dizziness), followed by the Moderna and viral vector vaccines. Females and underweight participants experienced more adverse effects with both vaccines, and fewer common side effects were reported by all participants.

How to prevent rubella epidemics and congenital rubella syndrome: lessons from 42 years of longitudinal epidemiology in Osaka Prefecture, Japan (1982-2023).

BACKGROUND: Despite the introduction of rubella-containing vaccine into routine immunization in 1977, rubella has not been eliminated in Japan. This study aimed to validate the immunization strategy and to highlight the crucial elements of elimination program. METHODS: We scrutinized cases of rubella and congenital rubella syndrome (CRS). Additionally, we analyzed the national vaccination coverage, seroprevalence, and number of maternal rubella-related spontaneous or artificial fetal deaths. RESULTS: The shift from selective to universal immunization significantly reduced rubella cases coupled with increased seroprevalence in children. However, rubella resurged in 2012-2013 and 2018-2019, which was virologically and serologically confirmed to be associated with imported rubella virus (RuV) and susceptible males. Although the disease burden of CRS may have been suppressed in the past by the large number of spontaneous or artificial fetal deaths, the incidence rate of CRS was comparable to that of the 1960s to 1980s. Cases of breakthrough infection and CRS were identified in females who were considered to have a history of single-dose vaccination. CONCLUSIONS: Even with universal immunization, future epidemics and severe outcomes cannot be prevented unless immunization gaps are closed. Furthermore, CRS and breakthrough infection are not completely prevented by single-dose vaccination, indicating the need for second-dose vaccination.

Antigenic sin and multiple breakthrough infections drive converging evolution of COVID-19 neutralizing responses.

Understanding the evolution of the B cell response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants is fundamental to design the next generation of vaccines and therapeutics. We longitudinally analyze at the single-cell level almost 900 neutralizing human monoclonal antibodies (nAbs) isolated from vaccinated people and from individuals with hybrid and super hybrid immunity (SH), developed after three mRNA vaccine doses and two breakthrough infections. The most potent neutralization and Fc functions against highly mutated variants belong to the SH cohort. Repertoire analysis shows that the original Wuhan antigenic sin drives the convergent expansion of the same B cell germlines in vaccinated and SH cohorts. Only Omicron breakthrough infections expand previously unseen germ lines and generate broadly nAbs by restoring IGHV3-53/3-66 germ lines. Our analyses find that B cells initially expanded by the original antigenic sin continue to play a fundamental role in the evolution of the immune response toward an evolving virus.

Anti-RBD Antibody Levels and IFN-γ-Specific T Cell Response Are Associated with a More Rapid Swab Reversion in Patients with Multiple Sclerosis after the Booster Dose of COVID-19 Vaccination.

This study investigated the incidence and severity of SARS-CoV-2 breakthrough infections (BIs) and the time to swab reversion in patients with multiple sclerosis (PwMS) after the booster dose of COVID-19 mRNA vaccines. We enrolled 64 PwMS who had completed the three-dose mRNA vaccine schedule and had never experienced COVID-19 before. Among the 64 PwMS, 43.8% had BIs with a median time since the third vaccine dose of 155 days. BIs occurred more frequently in ocrelizumab-treated patients (64.7%). Patients with a relapsing-remitting MS course showed a reduced incidence of BIs compared with those with a primary-progressive disease (p = 0.002). Having anti-receptor-binding domain (RBD) antibodies represented a protective factor reducing the incidence of BIs by 60% (p = 0.042). The majority of BIs were mild, and the only severe COVID-19 cases were reported in patients with a high Expanded Disability Status Scale score (EDSS > 6). The median time for a negative swab was 11 days. Notably, fingolimod-treated patients take longer for a swab-negativization (p = 0.002). Conversely, having anti-RBD antibodies ≥ 809 BAU/mL and an IFN-γ-specific T cell response ≥ 16 pg/mL were associated with a shorter time to swab-negativization (p = 0.051 and p = 0.018, respectively). In conclusion, the immunological protection from SARS-CoV-2 infection may differ among PwMS according to DMTs.

BCG vaccination of healthcare workers for protection against COVID-19: 12-month outcomes from an international randomised controlled trial.

OBJECTIVES: Bacille Calmette-Guérin (BCG) vaccine has immunomodulatory effects that may provide protection against unrelated infectious diseases. We aimed to determine whether BCG vaccination protects adults against COVID-19. DESIGN: Phase III double-blind randomised controlled trial. SETTING: Healthcare centres in Australia, Brazil, the Netherlands, Spain, and the United Kingdom during the COVID-19 pandemic. PARTICIPANTS: 3988 healthcare workers with no prior COVID-19 and no contraindication to BCG. INTERVENTION: Randomised 1:1 using a web-based procedure to receive a single 0.1 mL intradermal dose of BCG-Denmark (BCG group, n = 1999) or saline (placebo group, n = 1989). MAIN OUTCOME MEASURES: Difference in incidence of (i) symptomatic and (ii) severe COVID-19 during the 12 months following randomisation in the modified intention to treat (mITT) population (confirmed SARS-CoV-2 naïve at inclusion). RESULTS: Of the 3988 participants randomised, 3386 had a negative baseline SARS-CoV-2 test and were included in the mITT population. The 12-month adjusted estimated risk of symptomatic COVID-19 was higher in the BCG group (22.6%; 95% confidence interval [CI] 20.6 to 24.5%) compared with the placebo group (19.6%; 95% CI 17.6 to 21.5%); adjusted difference +3.0% points (95% CI 0.2 to 5.8%; p = 0.04). The 12-month adjusted estimated risk of severe COVID-19 (mainly comprising those reporting being unable to work for ≥3 consecutive days) was 11.0% in the BCG group (95% CI 9.5 to 12.4%) compared with 9.6% in the placebo group (95% CI 8.3 to 11.1%); adjusted difference +1.3% points (95% CI -0.7 to 3.3%, p = 0.2). Breakthrough COVID-19 (post COVID-19 vaccination) and asymptomatic SARS-CoV-2 infections were similar in the two groups. There were 18 hospitalisations due to COVID-19 (11 in BCG group, 7 in placebo group; adjusted hazard ratio 1.56, 95% CI 0.60 to 4.02, p = 0.4) and two deaths due to COVID-19, both in the placebo group. CONCLUSIONS: Compared to placebo, vaccination with BCG-Denmark increased the risk of symptomatic COVID-19 over 12 months among healthcare workers and did not decrease the risk of severe COVID-19 or post-vaccination breakthrough COVID-19. TRIAL REGISTRATION: ClinicalTrials.gov NCT04327206.

Immunity against conserved epitopes dominates after two consecutive exposures to SARS-CoV-2 Omicron BA.1.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exposure histories become increasingly complex through original and variant-adapted vaccines and infections with viral variants. Upon exposure to the highly altered Omicron spike glycoprotein, pre-immunized individuals predominantly mount recall responses of Wuhan-Hu-1 (wild-type)-imprinted memory B (BMEM) cells mostly targeting conserved non-neutralizing epitopes, leading to diminished Omicron neutralization. We investigated the impact of imprinting in individuals double/triple vaccinated with a wild-type-strain-based mRNA vaccine who, thereafter, had two consecutive exposures to Omicron BA.1 spike (breakthrough infection followed by BA.1-adapted vaccine). We found that depletion of conserved epitope-recognizing antibodies using a wild-type spike bait results in strongly diminished BA.1 neutralization. Furthermore, spike-specific BMEM cells recognizing conserved epitopes are much more prevalent than BA.1-specific BMEM cells. Our observations suggest that imprinted BMEM cell recall responses limit the induction of strain-specific responses even after two consecutive BA.1 spike exposures. Vaccine adaptation strategies need to consider that prior SARS-CoV-2 infections and vaccinations may cause persistent immune imprinting.

Assessing clinical benefits of live-attenuated vaccination in post-liver transplant patients: Analysis of breakthrough infections and natural boosters.

Recently, live-attenuated measles, rubella, varicella, and mumps vaccines have been administered to carefully selected post-liver transplant patients. Although attention has been focused on post-vaccination antibody titers and adverse events, the real-life clinical benefits remain unclear. A comprehensive analysis of breakthrough infections and natural boosters (asymptomatic cases with significant elevation in virus antibody titers) following immunization post-liver transplantation was conducted from 2002-2023, exploring the timing, frequency, correlation with domestic outbreaks, and degree of antibody elevation. During the median 10-year observation period among 68 post-liver transplant patients, breakthrough infections occurred only in chickenpox, with 7 mild cases (1 episode/64 person-years). A total of 59 natural booster episodes (1, 5, 20, and 33 for measles, rubella, chickenpox, and mumps, respectively) were observed, with incidence rates of 1 per 569, 110, 22, and 17 person-years, respectively. The timing of natural boosters closely correlated with domestic outbreaks (P < .05 in chickenpox and mumps), influenced by local vaccine coverage. The degree of antibody elevation was significantly higher in individuals with breakthrough infections than in those with natural boosters (P < .05). These findings suggest that immunization with live-attenuated vaccines for post-liver transplant patients has demonstrated clinical benefits. Furthermore, mass vaccination has a positive impact on post-transplant patient outcomes.

Breakthrough COVID-19 Infections after Booster SARS-CoV-2 Vaccination in a Greek Cohort of People Living with HIV during the Delta and Omicron Waves.

INTRODUCTION: Currently approved SARS-CoV-2 vaccines have been proven effective in protecting against severe COVID-19; however, they show variable efficacy against symptomatic infection and disease transmission. We studied the breakthrough COVID-19 infection (BTI) after booster vaccination against SARS-CoV-2 in people living with HIV (PWH). METHODS: This was a retrospective, single-center, descriptive cohort study involving PWH, who were followed in the HIV Clinic of "Attikon" University Hospital in Athens, Greece. A BTI was defined as a case of laboratory-confirmed COVID-19 occurring at least 14 days after the third (booster) vaccine dose. RESULTS: We studied 733 PWH [males: 89%, mean age: 45.2 ± 11.3 years, mean BMI: 26.1 ± 4.1, HIV stage at diagnosis (CDC classification): A/B/C = 80/9/11%, MSM: 72.6%] with well-controlled HIV infection. At least one comorbidity was recorded in 54% of cases. A history of ≥1 vaccination was reported by 90%, with 75% having been vaccinated with ≥3 vaccines. Four hundred and two (55%) PWH had a history of COVID-19 and 302 (41.2%) had a BTI, with only 15 (3.7%) needing hospitalization. Only one patient was admitted to the ICU, and no death was reported. Regarding BTI after booster dose, increased age (OR = 0.97, 95% CI: 0.96-0.99, per 1-year increase), and COVID-19 infection prior to booster dose (OR = 0.38, 95% CI: 0.21-0.68) were associated with a lower likelihood for BTI, whereas higher BMI (OR = 1.04, 95% CI: 1.01-1.08) and MSM as a mode of HIV transmission were associated with increased risk (OR = 2.59, 95% CI: 1.47-4.56). The incidence rate of total COVID-19 and BTI followed the epidemic curve of the general population, with the highest incidence recorded in June 2022. CONCLUSIONS: A significant proportion of PWH with well-controlled HIV infection experienced a BTI, with the majority of them having mild infection. These data, which include the period of Omicron variant predominance, confirm the importance of vaccination in the protection against severe COVID-19.

Impact of vaccination on SARS-CoV-2 evolution and immune escape variants.

Vaccines and host genetic factors can influence the SARS-CoV-2 evolution and emergence of new variants. Even vaccinated cases get affected as virus continues to evolve, raising concerns about vaccine efficacy and the emergence of immune escape variants. Here, we have analyzed 2295 whole-genome sequences of SARS-CoV-2 collected from vaccinated and unvaccinated cases to evaluate the impact of vaccines on virus diversity within hosts. Our comparative analysis revealed a significant higher incidence of intra-host single nucleotides variants (iSNVs) in vaccinated cases compared to unvaccinated ones (p value<0.0001). Furthermore, we have found that specific mutational processes, including APOBEC (C > T) mediated and ADAR1 (A > G) mediated mutations, were found more prevalent in vaccinated cases. Vaccinated cases exhibited higher accumulation of nonsynonymous mutation than unvaccinated cases. Fixed iSNVs were predominantly located in the ORF1ab and spike genes, several key omicron defining immune escape variants S477N, Q493R, Q498R, Y505H, L452R, and N501Y were identified in the RBD domain of spike gene in vaccinated cases. Our findings suggest that vaccine plays an important role in the evolution of the virus genome. The virus genome acquires random mutations due to error-prone replication of the virus, host modification through APOBEC and ADAR1 mediated editing mechanism, and oxidative stress. These mutations become fixed in the viral population due to the selective pressure imposed by vaccination.

SARS-CoV-2 BA.4/5 infection triggers more cross-reactive FcγRIIIa signaling and neutralization than BA.1, in the context of hybrid immunity.

SARS-CoV-2 variants of concern (VOCs) differentially trigger neutralizing and antibody-dependent cellular cytotoxic (ADCC) antibodies with variable cross-reactivity. Omicron BA.4/5 was approved for inclusion in bivalent vaccination boosters, and therefore the antigenic profile of antibodies elicited by this variant is critical to understand. Here, we investigate the ability of BA.4/5-elicited antibodies following the first documented (primary) infection (n = 13) or breakthrough infection after vaccination (n = 9) to mediate neutralization and FcγRIIIa signaling across multiple SARS-CoV-2 variants including XBB.1.5 and BQ.1. Using a pseudovirus neutralization assay and a FcγRIIIa crosslinking assay to measure ADCC potential, we show that unlike SARS-CoV-2 Omicron BA.1, BA.4/5 infection triggers highly cross-reactive functional antibodies. Cross-reactivity was observed both in the absence of prior vaccination and in breakthrough infections following vaccination. However, BQ.1 and XBB.1.5 neutralization and FcγRIIIa signaling were significantly compromised compared to other VOCs, regardless of prior vaccination status. BA.4/5 triggered FcγRIIIa signaling was significantly more resilient against VOCs (<10-fold decrease in magnitude) compared to neutralization (10- to 100-fold decrease). Overall, this study shows that BA.4/5 triggered antibodies are highly cross-reactive compared to those triggered by other variants. Although this is consistent with enhanced neutralization and FcγRIIIa signaling breadth of BA.4/5 vaccine boosters, the reduced activity against XBB.1.5 supports the need to update vaccines with XBB sublineage immunogens to provide adequate coverage of these highly antibody evasive variants. IMPORTANCE: The continued evolution of SARS-CoV-2 has resulted in a number of variants of concern. Of these, the Omicron sublineage is the most immune evasive. Within Omicron, the BA.4/5 sublineage drove the fifth wave of infection in South Africa prior to becoming the dominant variant globally. As a result this spike sequence was approved as part of a bivalent vaccine booster, and rolled out worldwide. We aimed to understand the cross-reactivity of neutralizing and Fc mediated cytotoxic functions elicited by BA.4/5 infection following infection or breakthrough infection. We find that, in contrast to BA.1 which triggered fairly strain-specific antibodies, BA.4/5 triggered antibodies that are highly cross-reactive for neutralization and antibody-dependent cellular cytotoxicity potential. Despite this cross-reactivity, these antibodies are compromised against highly resistant variants such as XBB.1.5 and BQ.1. This suggests that next-generation vaccines will require XBB sublineage immunogens in order to protect against these evasive variants.

Neutralization of SARS-CoV-2 Omicron XBB.1.5 and JN.1 variants after COVID-19 booster-vaccination and infection.

SARS-CoV-2 Omicron lineages continue to emerge and evolve into new sublineages, causing infection waves throughout 2022 and 2023, which has been attributed to immune escape. We examined neutralizing antibody responses to the recently emerged SARS-CoV-2 JN.1 variant in comparison to ancestral D614G and Omicron BA.1, BA.2, BA.5, and XBB.1.5 variants. We tested 79 human sera from cohorts with different combinations of vaccinations and infections, including 23 individuals who had been repeatedly exposed to Omicron. Individuals with a monovalent XBB.1.5 vaccine booster or XBB.1.5 breakthrough infection had robust antibody levels against all variants tested; however, JN.1 evaded antibodies in individuals after single Omicron BA.1, BA.2 or BA.5 breakthrough infections. Moreover, in the non-vaccinated cohort, serum antibodies demonstrated almost no cross-neutralization activities against D614G, XBB.1.5 and JN.1. after infections with earlier Omicron variants. These findings show that SARS-CoV-2-immunity is heterogeneous, depending on different combinations of vaccinations and infections, and emphasize the importance of considering different immune-backgrounds when evaluating novel variants.

Variant-specific antibody response following repeated SARS-CoV-2 vaccination and infection.

The ongoing emergence of SARS-CoV-2 variants poses challenges to the immunity induced by infections and vaccination. We conduct a 6-month longitudinal evaluation of antibody binding and neutralization of sera from individuals with six different combinations of vaccination and infection against BA.5, XBB.1.5, EG.5.1, and BA.2.86. We find that most individuals produce spike-binding IgG or neutralizing antibodies against BA.5, XBB.1.5, EG.5.1, and BA.2.86 2 months after infection or vaccination. However, compared to ancestral strain and BA.5 variant, XBB.1.5, EG.5.1, and BA.2.86 exhibit comparable but significant immune evasion. The spike-binding IgG and neutralizing antibody titers decrease in individuals without additional antigen exposure, and <50% of individuals neutralize XBB.1.5, EG.5.1, and BA.2.86 during the 6-month follow-up. Approximately 57% of the 107 followed up individuals experienced an additional infection, leading to improved binding IgG and neutralizing antibody levels against these variants. These findings provide insights into the impact of SARS-CoV-2 variants on immunity following repeated exposure.

Adolescents With Breakthrough COVID-19 Infections Requiring Hospitalization: A Multicenter Retrospective Study.

Background Vaccines have the most important role in the battle against the COVID-19 pandemic. With the widespread use of vaccines, COVID-19 has remarkably declined. Adolescents were vaccinated after approvals for this age group, which was later than adults, and a nationwide vaccination program was implemented in August 2021 in Turkey for adolescents ≥12 years of age. Therefore, we aimed to determine the effects of the COVID-19 nationwide adolescent vaccination program on adolescent hospitalizations due to COVID-19 and multisystem inflammatory syndrome in children (MIS-C) by comparing two periods, including the vaccination period (VP) and the pre-VP (PVP). The second aim of this study is to compare the clinical features and disease severity of vaccine-breakthrough COVID-19 hospitalizations with unvaccinated individuals in the VP. Methods A retrospective multicenter study was conducted to determine and compare the number of hospitalizations due to COVID-19 and MIS-C between the VP (September 1, 2021, to August 31, 2022) and PVP (September 1, 2020, to August 31, 2021). We also compared the characteristics, risk factors, and outcomes of breakthrough infections of adolescents aged 12-18, which required hospitalization with the same age group of unvaccinated hospitalized individuals during the VP. Results During the study period, 3967 children (0-18 years) were hospitalized in the PVP and 5143 (0-18 years) in the VP. Of them, 35.4% were adolescents (12-18 years) in the PVP, and this rate was 18.6% in the VP; relative risk was 0.6467 (95% confidence interval [CI]: 0.6058-0.6904; p < 0.001). Patients with breakthrough COVID-19 were older (201 vs. 175 months, p < 0.001) and less commonly hospitalized for COVID-19 (81.5% vs. 60.4%, p < 0.001, odds ratio [OR]: 0.347 [95% CI: 0.184-0.654]). The majority of these infections were asymptomatic and mild (32% vs.72.9%: p < 0.001, OR: 5.718 [95% CI: 2.920-11.200]), and PICU admission was less frequently required (p = 0.011, OR: 0.188 [95% CI: 0.045-0.793]). Most breakthrough COVID-19 infections occurred within three months after the last vaccine dose (54.2%). Conclusions This study demonstrated a significant decrease in adolescent hospitalizations due to COVID-19 and MIS-C after implementing COVID-19 vaccines in Turkey. Breakthrough cases were less severe and mostly occurred three months after the last dose. This study emphasizes the importance of COVID-19 vaccines and that parents' decisions may be changed, particularly those who hesitate to or refuse vaccination.

Immune cell populations and induced immune responses at admission in patients hospitalized with vaccine breakthrough SARS-CoV-2 infections.

Background: Vaccine breakthrough SARS-CoV-2 infections are common and of clinical and public health concern. However, little is known about the immunological characteristics of patients hospitalized due to these infections. We aimed to investigate and compare immune cell subpopulations and induced immune responses in vaccinated and non-vaccinated patients hospitalized with severe COVID-19. Methods: A nested case-control study on adults (≥ 18 years) who received at least two doses of a mRNA-COVID-19 vaccine and were hospitalized with SARS-CoV-2 breakthrough infections and severe COVID-19 between January 7, 2021, and February 1, 2022, were eligible for inclusion. Age- and sex-matched non-vaccinated controls were identified. Immunophenotyping was performed using a custom-designed 10-color flow cytometry prefabricated freeze-dried antibody panel (DuraClone, Beckman Coulter (BC), Brea, Calif). TruCulture (Myriad RBM, Austin, USA) was used to assess induced immune response in whole blood, revealing different critical signaling pathways as a proxy for immune function. All samples were obtained within 48 hours of admission. Results: In total, 20 hospitalized patients with severe COVID-19 and a breakthrough SARS-CoV-2 infection were included, ten vaccinated and ten non-vaccinated patients. Vaccinated patients had lower concentrations of CD19 B cells (p = 0.035), naïve CD4 T cells (p = 0.015), a higher proportion of γδ1 T cells (p = 0.019), and higher unstimulated immune cell release of IL-10 (p = 0.015). Conclusion: We observed immunological differences between vaccinated and non-vaccinated patients hospitalized due to severe COVID-19 that indicate that vaccinated patients had lower B cell concentrations, lower concentrations of CD4 naïve T cells, a skewed gamma-delta V1/V2 ratio, and an exaggerated IL-10 response at admission. These results could indicate a suboptimal immune response involved in SARS-CoV-2 breakthrough infections that cause severe COVID-19 in vaccinated adults. However, the sample size was small, and further research is needed to confirm these results.

Declining Levels of Neutralizing Antibodies to SARS-CoV-2 Omicron Variants Are Enhanced by Hybrid Immunity and Original/Omicron Bivalent Vaccination.

We determined neutralizing antibody levels to the ancestral Wuhan SARS-CoV-2 strain and three Omicron variants, namely BA.5, XBB.1.5, and EG.5, in a heavily vaccinated cohort of 178 adults 15-19 months after the initial vaccine series and prospectively after 4 months. Although all participants had detectable neutralizing antibodies to Wuhan, the proportion with detectable neutralizing antibodies to the Omicron variants was decreased, and the levels were lower. Individuals with hybrid immunity at the baseline visit and those receiving the Original/Omicron bivalent vaccine between the two sampling times demonstrated increased neutralizing antibodies to all strains. Both a higher baseline neutralizing antibody titer to Omicron BA.5 and hybrid immunity were associated with protection against a breakthrough SARS-CoV-2 infection during a 4-month period of follow up during the Omicron BA.5 wave. Neither were associated with protection from a breakthrough infection at 10 months follow up. Receipt of an Original/Omicron BA.4/5 vaccine was associated with protection from a breakthrough infection at both 4 and 10 months follow up. This work demonstrates neutralizing antibody escape with the emerging Omicron variants and supports the use of additional vaccine doses with components that match circulating SARS-CoV-2 variants. A threshold value for neutralizing antibodies for protection against reinfection cannot be determined.

COVID-19 Breakthrough Infections among Medical Students under the SLICE and CLARO Programs: Ateneo School of Medicine and Public Health Experience.

Objective: This study aims to report the incidence and characteristics of breakthrough infections among medical students in the first Philippine private medical school that resumed limited face-to-face classes and clinical rotations from July to December 2021. Methods: This is a descriptive study using secondary worksheet from multiple-source records review of breakthrough infections among medical students from July to December 2021. Results: Among the 837 vaccinated medical students, 23 (2.7%) experienced COVID-19 breakthrough infections. Of these, 9 were male and 14 were female. Four were asymptomatic and 19 were symptomatic. Of the 19 symptomatic, 18 had mild and 1 had severe disease. Mild infections presented with upper respiratory tract symptoms. Duration of symptoms ranged from 4 to 27 days with an average of 10 days. Timing of breakthrough infections ranged from 35 to 212 days after the second dose of COVID-19 vaccine with a mean of 86 days. Contact with confirmed cases was reported in 14 of 23 cases, 13 were from household members and none within the SLICE and CLARO programs. Conclusion: Our study showed that even in the midst of the Delta surge, low breakthrough infection rate with mostly mildly symptomatic cases and no case transmissions within the SLICE and CLARO programs are possible with vaccination, regular health surveillance, and strict adherence to minimum health protocols.

Hybrid immunity by two COVID-19 mRNA vaccinations and one breakthrough infection provides a robust and balanced cellular immune response as basic immunity against severe acute respiratory syndrome coronavirus 2.

This longitudinal prospective controlled multicenter study aimed to monitor immunity generated by three exposures caused by breakthrough infections (BTI) after COVID-19-vaccination considering pre-existing cell-mediated immunity to common-corona-viruses (CoV) which may impact cellular reactivity against SARS-CoV-2. Anti-SARS-CoV-2-spike-IgG antibodies (anti-S-IgG) and cellular reactivity against Spike-(S)- and nucleocapsid-(N)-proteins were determined in fully-vaccinated (F) individuals who either experienced BTI (F+BTI) or had booster vaccination (F+Booster) compared to partially vaccinated (P+BTI) and unvaccinated (U) from 1 to 24 weeks post PCR-confirmed infection. High avidity anti-S-IgG were found in F+BTI compared to U, the latter exhibiting increased long-lasting pro-inflammatory cytokines to S-stimulation. CoV was associated with higher cellular reactivity in U, whereas no association was seen in F. The study illustrates the induction of significant S-specific cellular responses in F+BTI building-up basic immunity by three exposures. Only U seem to benefit from pre-existing CoV immunity but demonstrated inflammatory immune responses compared to F+BTI who immunologically benefit from enhanced humoral and cellular immunity after BTI. This study demonstrates that individuals with hybrid immunity from COVID-19-vaccination and BTI acquire a stable humoral and cellular immune response that is maintained for at least 6 months. Our findings corroborate recommendations by health authorities to build on basic immunity by three S-protein exposures.