A remarkable genetic shift in a transmitted/founder virus broadens antibody responses against HIV-1.

A productive HIV-1 infection in humans is often established by transmission and propagation of a single transmitted/founder (T/F) virus, which then evolves into a complex mixture of variants during the lifetime of infection. An effective HIV-1 vaccine should elicit broad immune responses in order to block the entry of diverse T/F viruses. Currently, no such vaccine exists. An in-depth study of escape variants emerging under host immune pressure during very early stages of infection might provide insights into such a HIV-1 vaccine design. Here, in a rare longitudinal study involving HIV-1 infected individuals just days after infection in the absence of antiretroviral therapy, we discovered a remarkable genetic shift that resulted in near complete disappearance of the original T/F virus and appearance of a variant with H173Y mutation in the variable V2 domain of the HIV-1 envelope protein. This coincided with the disappearance of the first wave of strictly H173-specific antibodies and emergence of a second wave of Y173-specific antibodies with increased breadth. Structural analyses indicated conformational dynamism of the envelope protein which likely allowed selection of escape variants with a conformational switch in the V2 domain from an α-helix (H173) to a ß-strand (Y173) and induction of broadly reactive antibody responses. This differential breadth due to a single mutational change was also recapitulated in a mouse model. Rationally designed combinatorial libraries containing 54 conformational variants of V2 domain around position 173 further demonstrated increased breadth of antibody responses elicited to diverse HIV-1 envelope proteins. These results offer new insights into designing broadly effective HIV-1 vaccines.

Vaccine development: obligate intracellular bacteria new tools, old pathogens: the current state of vaccines against obligate intracellular bacteria.

Obligate intracellular bacteria have remained those for which effective vaccines are unavailable, mostly because protection does not solely rely on an antibody response. Effective antibody-based vaccines, however, have been developed against extracellular bacteria pathogens or toxins. Additionally, obligate intracellular bacteria have evolved many mechanisms to subvert the immune response, making vaccine development complex. Much of what we know about protective immunity for these pathogens has been determined using infection-resolved cases and animal models that mimic disease. These studies have laid the groundwork for antigen discovery, which, combined with recent advances in vaccinology, should allow for the development of safe and efficacious vaccines. Successful vaccines against obligate intracellular bacteria should elicit potent T cell memory responses, in addition to humoral responses. Furthermore, they ought to be designed to specifically induce strong cytotoxic CD8+ T cell responses for protective immunity. This review will describe what we know about the potentially protective immune responses to this group of bacteria. Additionally, we will argue that the novel delivery platforms used during the Sars-CoV-2 pandemic should be excellent candidates to produce protective immunity once antigens are discovered. We will then look more specifically into the vaccine development for Rickettsiaceae, Coxiella burnetti, and Anaplasmataceae from infancy until today. We have not included Chlamydia trachomatis in this review because of the many vaccine related reviews that have been written in recent years.

Antibody response to malaria vaccine candidates in pregnant women with Plasmodium falciparum and Schistosoma haematobium infections.

Malaria in pregnancy has severe consequences for the mother and foetus. Antibody response to specific malaria vaccine candidates (MVC) has been associated with a decreased risk of clinical malaria and its outcomes. We studied Plasmodium falciparum (Pf) and Schistosoma haematobium (Sh) infections and factors that could influence antibody responses to MVC in pregnant women. A total of 337 pregnant women receiving antenatal care (ANC) and 139 for delivery participated in this study. Pf infection was detected by qPCR and Sh infection using urine filtration method. Antibody levels against CSP, AMA-1, GLURP-R0, VAR2CSA and Pfs48/45 MVC were quantified by ELISA. Multivariable linear regression models identified factors associated with the modulation of antibody responses. The prevalence of Pf and Sh infections was 27% and 4% at ANC and 7% and 4% at delivery. Pf infection, residing in Adidome and multigravidae were positively associated with specific IgG response to CSP, AMA-1, GLURP-R0 and VAR2CSA. ITN use and IPTp were negatively associated with specific IgG response to GLURP-R0 and Pfs48/45. There was no association between Sh infection and antibody response to MVC at ANC or delivery. Pf infections in pregnant women were positively associated with antibody response to CSP, GLURP-R0 and AMA-1. Antibody response to GLURP-R0 and Pfs48/45 was low for IPTp and ITN users. This could indicate a lower exposure to Pf infection and low malaria prevalence observed at delivery.

Determinants of health as predictors for differential antibody responses following SARS-CoV-2 primary and booster vaccination in an at-risk, longitudinal cohort.

Post vaccine immunity following COVID-19 mRNA vaccination may be driven by extrinsic, or controllable and intrinsic, or inherent health factors. Thus, we investigated the effects of extrinsic and intrinsic on the peak antibody response following COVID-19 primary vaccination and on the trajectory of peak antibody magnitude and durability over time. Participants in a longitudinal cohort attended visits every 3 months for up to 2 years following enrollment. At baseline, participants provided information on their demographics, recreational behaviors, and comorbid health conditions which guided our model selection process. Blood samples were collected for serum processing and spike antibody testing at each visit. Cross-sectional and longitudinal models (linear-mixed effects models) were generated to assess the relationship between selected intrinsic and extrinsic health factors on peak antibody following vaccination and to determine the influence of these predictors on antibody over time. Following cross-sectional analysis, we observed higher peak antibody titers after primary vaccination in females, those who reported recreational drug use, younger age, and prior COVID-19 history. Following booster vaccination, females and Hispanics had higher peak titers after the 3rd and 4th doses, respectively. Longitudinal models demonstrated that Moderna mRNA-1273 recipients, females, and those previously vaccinated had increased peak titers over time. Moreover, drug users and half-dose Moderna mRNA-1273 recipients had higher peak antibody titers over time following the first booster, while no predictive factors significantly affected post-second booster antibody responses. Overall, both intrinsic and extrinsic health factors play a significant role in shaping humoral immunogenicity after initial vaccination and the first booster. The absence of predictive factors for second booster immunogenicity suggests a more robust and consistent immune response after the second booster vaccine administration.

Poor association between 13-valent pneumococcal conjugate vaccine-induced serum and mucosal antibody responses with experimental Streptococcus pneumoniae serotype 6B colonisation.

BACKGROUND: Pneumococcal carriage is the primary reservoir for transmissionand a prerequisite for invasive pneumococcal disease. Pneumococcal Conjugate Vaccine 13 (PCV13) showed a 62% efficacy in protection against experimental Streptococcus pneumoniae serotype 6B (Spn6B) carriage in a controlled human infection model (CHIM) of healthy Malawian adults. We, therefore, measured humoral responses to experimental challenge and PCV-13 vaccination and determined the association with protection against pneumococcal carriage. METHODS: We vaccinated 204 young, healthy Malawian adults with PCV13 or placebo and nasally inoculated them with Spn6B at least four weeks post-vaccination to establish carriage. We collected peripheral blood and nasal lining fluid at baseline, 4 weeks post-vaccination (7 days pre-inoculation), 2, 7, 14 and > 1 year post-inoculation. We measured the concentration of anti-serotype 6B Capsular Polysaccharide (CPS) Immunoglobulin G (IgG) and IgA antibodies in serum and nasal lining fluid using the World Health Organization (WHO) standardised enzyme-linked immunosorbent assay (ELISA). RESULTS: PCV13-vaccinated adults had higher serum IgG and nasal IgG/IgA anti-Spn6B CPS-specific binding antibodies than placebo recipients 4 to 6 weeks post-vaccination, which persisted for at least a year after vaccination. Nasal challenge with Spn6B did not significantly alter serum or nasal anti-CPS IgG binding antibody titers with or without experimental pneumococcal carriage. Pre-challenge titers of PCV13-induced serum IgG and nasal IgG/IgA anti-Spn6B CPS binding antibodies did not significantly differ between those that got experimentally colonised by Spn6B compared to those that did not. CONCLUSION: This study demonstrates that despite high PCV13 efficacy against experimental Spn6B carriage in young, healthy Malawian adults, robust vaccine-induced systemic and mucosal anti-Spn6B CPS binding antibodies did not directly relate to protection.

Post-vaccination SARS-CoV-2 IgG spike antibody responses among clinical and non-clinical healthcare workers at a tertiary facility in Kenya.

INTRODUCTION: Following the coronavirus disease 19 (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection, vaccination became the main strategy against disease severity and even death. Healthcare workers were considered high-risk for infection and, thus, were prioritised for vaccination. METHODS: A follow-up to a SARS-CoV-2 seroprevalence study among clinical and non-clinical HCWs at the Aga Khan University Hospital, Nairobi, we assessed how vaccination influenced SARS-CoV-2 anti-spike IgG antibody responses and kinetics. Blood samples were drawn at two points spanning 6 to 18 months post-vaccination, and SARS-CoV-2 spike antibody levels were determined by enzyme-linked immunosorbent assay. RESULTS: Almost all participants, 98% (961/981), received a second vaccine dose, and only 8.5% (83/981) received a third dose. SARS-CoV-2 spike IgG antibodies were detected in 100% (961/961) and 92.7% (707/762) of participants who received two vaccine doses, with the first and second post-vaccine test, respectively, and in 100% (83/83) and 91.4% (64/70) of those who received three vaccine doses at the first and second post-vaccine test, respectively. Seventy-six participants developed mild infections, not requiring hospitalisation even after receiving primary vaccination. Receiving three vaccine doses influenced the anti-spike S/Co at both the first (p<0.001) and second post-vaccination testing (p<0.001). Of those who tested SARS-CoV-2 positive, the anti-spike S/Co ratio was significantly higher than those who were seronegative at the first post-vaccine test (p = 0.001). Side effects were reported by almost half of those who received the first dose, 47.3% (464/981), 28.9% (278/961) and 25.3% (21/83) of those who received the second and third vaccine doses, respectively. DISCUSSION AND CONCLUSION: Following the second dose of primary vaccination, all participants had detectable anti-spike antibodies. The observed mild breakthrough infections may have been due to emerging SARS-CoV-2 variants. Findings suggest that although protective antibodies are induced, vaccination protected against COVID-19 disease severity and not necessarily infection.

An ELISA-Based Method to Measure Mucosal Antibody Responses Against SARS-CoV-2 in Human Saliva.

The primary mode of transmission for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is infection of the respiratory tract through droplets and/or aerosols. Therefore, immune responses at respiratory mucosal surfaces play a significant role in the prevention of infection. Greater emphasis is now being placed on mucosal immunity induced by exposure to SARS-CoV-2 antigens through infection or vaccination. In concert with cellular immunity, humoral responses at mucosal surfaces, especially the secretory version of immunoglobulin A (sIgA), can be instrumental in preventing respiratory infections. A better understanding of mucosal immune responses can further our knowledge of immunity to SARS-CoV-2 and help inform vaccine design. Here we describe a detailed protocol for an in vitro assay based on the enzyme-linked immunosorbent assay (ELISA) to assess mucosal antibody response to SARS-CoV-2 spike protein in human saliva. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol: ELISA measurement of mucosal antibodies to SARS-CoV-2 spike protein in human saliva.

Comparison of virus-neutralizing and virus-specific ELISA antibody responses among bovine neonates differentially primed and boosted against bovine coronavirus.

Objective: This study addressed the current gap in knowledge of neonatal prime-boost immune responses for the control of bovine coronavirus (BCoV) respiratory disease in weaning-age beef cattle. Animals: Study 1 and Study 2 had 33 and 22 commercial cross neonatal beef calves, respectively. Procedures: Study 1 compared BCoV-neutralizing antibody concentrations of control calves with 3 groups of calves differentially vaccinated with mucosal and/or systemic BCoV modified live virus (MLV) vaccines. Study 2 compared specific and neutralizing antibody concentrations among mucosally BCoV primed groups of calves that were differentially systemically boosted. Results: In Study 1, calves that were mucosally primed and systemically boosted had higher BCoV-neutralizing antibody concentrations than the control group at weaning. In Study 2, boosting mucosally primed calves by injecting inactivated or MLV vaccine resulted in anamnestic BCoV-specific antibody responses at weaning. Conclusion: Neonatal mucosal priming and systemic boosting resulted in anamnestic BCoV antibody responses at weaning. Clinical relevance: Prime-boost vaccination should be considered for control of BCoV respiratory disease.

Comparaison des réponses en anticorps ELISA neutralisant le virus et spécifiques du virus chez des nouveau-nés bovins vaccinés par amorces-rappels différenciés contre le coronavirus bovin. Objectif: Cette étude a abordé le manque actuel de connaissances sur les réponses immunitaires néonatales de stimulation pour maitriser la maladie respiratoire à coronavirus bovin (BCoV) chez les bovins de boucherie en âge de sevrage. Animaux: Les études 1 et 2 portaient respectivement sur 33 et 22 veaux de boucherie néonatals croisés commerciaux. Procédures: L'étude 1 a comparé les concentrations d'anticorps neutralisant le BCoV de veaux témoins avec 3 groupes de veaux vaccinés de manière différentielle avec des vaccins à virus vivant modifié (MLV) contre le BCoV pour administration par voie mucosale et/ou systémique. L'étude 2 a comparé les concentrations d'anticorps spécifiques et neutralisants parmi des groupes de veaux sensibilisés au BCoV par voie mucosale et qui ont eu un rappel par voie systémique différentielle. Résultats: Dans l'étude 1, les veaux qui avaient reçu une amorce au niveau des muqueuses et un rappel systémique présentaient des concentrations d'anticorps neutralisant le BCoV plus élevées que le groupe témoin au sevrage. Dans l'étude 2, le rappel des veaux amorcés par voie mucosale par l'injection d'un vaccin inactivé ou MLV a entraîné une réponse anamnestique en anticorps spécifiques du BCoV au sevrage. Conclusion: En période néonatale, l'amorce par voie mucosale et le renforcement systémique ont entraîné des réponses anamnestiques en anticorps BCoV au sevrage. Pertinence clinique: La vaccination de rappel doit être envisagée pour maitriser la maladie respiratoire causée par le BCoV.(Traduit par Dr Serge Messier).

Genomic determinants of antibody response to a typhoid vaccine in Indian recipients.

Typhoid is endemic in India and has high global incidence. There were large outbreaks of typhoid in India between 1990 and 2018. Available typhoid vaccines induce variable levels of protective antibodies among recipients; thus, there is variability in response to the vaccine. Interindividual genomic differences is hypothesized to be a determinant of the variability in response. We studied the antibody response of ~1000 recipients of the Vi-polysaccharide typhoid vaccine from Kolkata, India, who showed considerable variability of antibody response, i.e., anti-Vi-polysaccharide antibody level 28 days postvaccination relative to prevaccination. For each vaccinee, wholegenome genotyping was performed using the Infinium Global Screening Array (Illumina). We identified 39 SNPs that mapped to 13 chromosomal regions to be associated with antibody response to the vaccine; these included SNPs on genes LRRC28 (15q26.3), RGS7 (1q43), PTPRD (9p23), CERKL (2q31.3), DGKB (7p21.2), and TCF4 (18q21.2). Many of these loci are known to be associated with various blood cell traits, autoimmune traits and responses to other vaccines; these genes are involved in immune related functions, including TLR response, JAK-STAT signalling, phagocytosis and immune homeostasis.

The Inhibitory Effect of Early Pregnancy Factor on Red Meat Neu5Gc-Mediated Antibody Production in CMAH-/- Mice.

The meat derived from mammals such as cows, sheep, and pigs is commonly referred to as red meat. Recent studies have shown that consuming red meat can activate the immune system, produce antibodies, and subsequently develop into tumors and cancer. This is due to the presence of a potential carcinogenic compound in red meat called N-ethanol neuraminic acid (Neu5Gc). Neu5Gc is a common sialic monosaccharide in mammals, synthesized from N-acetylneuraminic acid (Neu5Ac) in the body and typically present in most mammals. However, due to the lack of the CMAH gene encoding the cytidine 5'-monophosphate Neu5Ac hydroxylase, humans are unable to synthesize Neu5Gc. Compared to primates such as mice or chimpanzees, the specific loss of Neu5Gc expression in humans is attributed to fixed genome mutations in CMAH. Although Neu5Gc cannot be produced, it can be introduced from specific dietary sources such as red meat and milk, so it is necessary to use mice or chimpanzees that knock out the CMAH gene instead of humans as experimental models. Further research has shown that early pregnancy factor (EPF) has the ability to regulate CD4+T cell-dependent immune responses. In this study, we established a simulated human animal model using C57/BL6 mice with CMAH gene knockout and analyzed the inhibitory effect of EPF on red meat Neu5Gc-induced CMAH-/- C57/BL6 mouse antibody production and chronic inflammation development. The results showed that the intervention of EPF reduced slow weight gain and shortened colon length in mice. In addition, EPF treatment significantly reduced the levels of anti Neu5Gc antibodies in the body, as well as the inflammatory factors IL-6 and IL-1ß, TNF-α and the activity of MPO. In addition, it also alleviated damage to liver and intestinal tissues and reduced the content of CD4 cells and the expression of B cell activation molecules CD80 and CD86 in mice. In summary, EPF effectively inhibited Neu5Gc-induced antibody production, reduced inflammation levels in mice, and alleviated Neu5Gc-induced inflammation. This will provide a new re-search concept and potential approach for developing immunosuppressants to address safety issues related to long-term consumption of red meat.

Viral Epitope Scanning Reveals Correlation between Seasonal HCoVs and SARS-CoV-2 Antibody Responses among Cancer and Non-Cancer Patients.

Seasonal coronaviruses (HCoVs) are known to contribute to cross-reactive antibody (Ab) responses against SARS-CoV-2. While these responses are predictable due to the high homology between SARS-CoV-2 and other CoVs, the impact of these responses on susceptibility to SARS-CoV-2 infection in cancer patients is unclear. To investigate the influence of prior HCoV infection on anti-SARS-CoV-2 Ab responses among COVID-19 asymptomatic individuals with cancer and controls without cancers, we utilized the VirScan technology in which phage immunoprecipitation and sequencing (PhIP-seq) of longitudinal plasma samples was performed to investigate high-resolution (i.e., epitope level) humoral CoV responses. Despite testing positive for anti-SARS-CoV-2 Ab in the plasma, a majority of the participants were asymptomatic for COVID-19 with no prior history of COVID-19 diagnosis. Although the magnitudes of the anti-SARS-CoV-2 Ab responses were lower in individuals with Kaposi sarcoma (KS) compared to non-KS cancer individuals and those without cancer, the HCoV Ab repertoire was similar between individuals with and without cancer independent of age, sex, HIV status, and chemotherapy. The magnitudes of the anti-spike HCoV responses showed a strong positive association with those of the anti-SARS-CoV-2 spike in cancer patients, and only a weak association in non-cancer patients, suggesting that prior infection with HCoVs might play a role in limiting SARS-CoV-2 infection and COVID-19 disease severity.

A High Threshold of Biotherapeutic Aggregate Numbers is Needed to Induce an Immunogenic Response In Vitro, In Vivo, and in the Clinic.

BACKGROUND AND PURPOSE: There is concern that subvisible aggregates in biotherapeutic drug products pose a risk to patient safety. We investigated the threshold of biotherapeutic aggregates needed to induce immunogenic responses. METHODS AND RESULTS: Highly aggregated samples were tested in cell-based assays and induced cellular responses in a manner that depended on the number of particles. The threshold of immune activation varied by disease state (cancer, rheumatoid arthritis, allergy), concomitant therapies, and particle number. Compared to healthy donors, disease state patients showed an equal or lower response at the late phase (7 days), suggesting they may not have a higher risk of responding to aggregates. Xeno-het mice were used to assess the threshold of immune activation in vivo. Although highly aggregated samples (~ 1,600,000 particles/mL) induced a weak and transient immunogenic response in mice, a 100-fold dilution of this sample (~ 16,000 particles/mL) did not induce immunogenicity. To confirm this result, subvisible particles (up to ~ 18,000 particles/mL, containing aggregates and silicone oil droplets) produced under representative administration practices (created upon infusion of a drug product through an IV catheter) did not induce a response in cell-based assays or appear to increase the rate of adverse events or immunogenicity during phase 3 clinical trials. CONCLUSION: The ability of biotherapeutic aggregates to elicit an immune response in vitro, in vivo, and in the clinic depends on high numbers of particles. This suggests that there is a high threshold for aggregates to induce an immunogenic response which is well beyond that seen in standard biotherapeutic drug products.

SARS-CoV-2 BA.1 and BA.2 breakthrough infections boost antibody responses to early Omicron subvariants but not BQ.1.1 or XBB.1.5.

Subvariants of the Omicron lineage of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) efficiently escape neutralizing antibody responses induced by both vaccination and infection with antigenically distinct variants. Here, we describe the potency and breadth of neutralizing and binding antibody responses against a large panel of variants following an Omicron BA.1 or BA.2 breakthrough infection in a heterogeneous cohort of individuals with diverse exposure histories. Both BA.1 and BA.2 breakthrough infections significantly boost antibody levels and broaden antibody reactivity. However, this broader immunity induced by BA.1 and BA.2 breakthrough infections does not neutralize Omicron BQ and XBB subvariants efficiently. While these subvariants are not neutralized well by post-breakthrough sera, suggesting escape, binding non-neutralizing antibody responses are sustained. In summary, our data suggest that while BA.1 and BA.2 breakthrough infections broaden the immune response to SARS-CoV-2 spike, the induced neutralizing antibody response is still outpaced by viral evolution.

Mycophenolate mofetil hampers antibody responses to a broad range of vaccinations in kidney transplant recipients: Results from a randomized controlled study.

OBJECTIVES: To study the effect of mycophenolate mofetil (MMF) on various vaccination responses in kidney transplant recipients. METHODS: In a randomized controlled trial (EudraCT nr.: 2014-001372-66), low immunologically risk kidney transplant recipients were randomized to TAC/MMF or TAC-monotherapy (TACmono), six months post-transplantation. One year after transplantation, in a pre-specified sub-study, recipients were vaccinated against pneumococcus, tetanus and influenza. Blood was sampled before and 21 days after vaccination. Adequate vaccination responses were defined by international criteria. A post-hoc analysis was conducted on SARS-CoV-2 vaccination responses within the same cohort. RESULTS: Seventy-one recipients received pneumococcal and tetanus vaccines (TAC/MMF: n = 37, TACmono: n = 34), with 29 also vaccinated against influenza. When vaccinated, recipients were 60 (54-66) years old, with median eGFR of 54 (44-67) ml/min, tacrolimus trough levels 6.1 (5.4-7.0) ug/L in both groups and TAC/MMF daily MMF dose of 1000 (500-2000) mg. Adequate vaccination responses were: pneumococcal (TAC/MMF 43%, TACmono 74%, p = 0.016), tetanus (TAC/MMF 35%, TACmono 82%, p < 0.0001) and influenza (TAC/MMF 20%, TACmono 71%, p = 0.0092). Only 7% of TAC/MMF responded adequately to all three compared to 36% of TACmono (p = 0.080). Additionally, 40% of TAC/MMF responded inadequately to all three, whereas all TACmono patients responded adequately to at least one vaccination (p = 0.041). Lower SARS-CoV-2 vaccination antibody responses correlated with lower pneumococcal antibody vaccination responses (correlation coefficient: 0.41, p = 0.040). CONCLUSIONS: MMF on top of tacrolimus severely hampers antibody responses to a broad range of vaccinations.

Methods for Analysis of Nanoparticle Immunosuppressive Properties.

Adverse drug effects on immune system function represent a significant concern in the pharmaceutical industry, because 10-20% of drug withdrawal from the market is attributed to immunotoxicity. Immunosuppression is one such adverse effect. The traditional immune function test used to estimate materials' immunosuppression is T cell dependent antibody response (TDAR). This method involves a 28-day in vivo study evaluating the animal's antibody titer to a known antigen (Keyhole Limpet Hemocyanin; KLH) with and without challenge. Due to the limited quantities of novel drug candidates, an in vitro method called human lymphocyte activation (HuLA) assay has been developed to substitute the traditional TDAR assay during early preclinical development. In this test, leukocytes isolated from healthy donors vaccinated with the current year's flu vaccine are incubated with Fluzone in the presence or absence of nanoparticles. The antigen-specific lymphocyte proliferation is then measured by ELISA analyzing incorporation of BrdU into DNA of the proliferating cells. Here we describe the experimental procedures for investigating immunosuppressive properties of nanoparticles by both TDAR and HuLA assays, discuss the in vitro-in vivo correlation of these methods, and show a case study using the iron oxide nanoparticle formulation, Feraheme.

Relationship among sleep, work features, and SARS-cov-2 vaccine antibody response in hospital workers.

STUDY OBJECTIVES: Immunity is influenced by sleep and the circadian rhythm. Healthcare workers are predisposed to both insufficient sleep and circadian disruption. This study aimed to evaluate the relationship between sleep and work characteristics and the antibody response to the mRNA SARS-CoV-2 vaccine BNT162b2. METHODS: The authors' prospective cohort study ("COVI3") evaluated the effect of a third (booster) dose of the BNT162b2 vaccine. A subset of participants provided information on anthropometric measures, sleep, stress and work characteristics including shift work and number of work hours per week. Blood samples for anti-S1-RBD IgG antibody levels were obtained 21 weeks following receipt of the third dose of the vaccine. RESULTS: In total, 201 healthcare workers (73% women) were included. After adjustment for age, body mass index (BMI), shift work, smoking status, and perceived stress, short sleep duration (<7 h per night) was associated with lower anti-S1-RBD IgG levels (Odds ratio 2.36 [95% confidence interval 1.08-5.13]). Participants who performed shift work had higher odds of lower anti-S1-RBD IgG levels compared to those who did not work in shifts [odds ratio = 2.99 (95% confidence interval 1.40, 6.39)] after accounting for age, short sleep duration, BMI, smoking status and perceived stress. CONCLUSIONS: Shift work and self-reported short sleep duration were associated with a lower antibody response following a booster dose of the SARS-CoV-2 vaccine. These findings suggest that the efficacy of vaccination, particularly among healthcare workers, may be augmented by addressing both sleep and circadian alignment.