Faculty Bibliography

Thrombotic risk in COVID-19 extends beyond acute illness, including in nonhospitalized individuals, suggesting that thrombo-inflammatory biology may persist during recovery. Longitudinal sampling with pre-infection baselines is needed to distinguish infection-associated signals from inter-individual variability and time-related drift in blood gene expression. To define coordinated, time-resolved whole-blood transcriptomic programs during SARS-CoV-2 convalescence using longitudinal within-person comparisons before and after infection, alongside COVID-19-naïve controls. Adults were sampled longitudinally with specimens collected before SARS-CoV-2 infection (T0) and at ~3 months (T1) and ~6 months (T2) post-infection; COVID-19-naïve controls were sampled across matched timepoints. COVID-19-naïve status was confirmed using a multiplex anti-nucleocapsid IgG assay spanning multiple variant antigens. Whole-blood RNA-seq (PAXgene) was analyzed with DESeq. 2 using models that incorporated time point and participant. To prioritize infection-linked changes, genes differentially expressed over time in controls were identified and excluded from comparisons between COVID-19 time points. Pathways were assessed by pre-ranked GSEA (MSigDB) and clustered with aPEAR. After excluding control-associated genes, COVID-19 convalescence remained associated with marked transcriptional remodeling (T1 vs. T0: 782 genes; T2 vs. T0: 655 genes; p < 0.05) and persistent pathway-level changes. Interferon-α and interferon-γ signatures were enriched at both T1 and T2, and a core set of interferon-associated genes remained elevated across convalescence. SARS-CoV-2 infection is followed by durable whole-blood immune-defense programs, including persistent interferon signaling, detectable up to 6 months post-infection. These sustained signatures support a model of prolonged post-infectious immune activation that may contribute to extended thromboinflammatory risk.

BACKGROUND:The 2022 global outbreak of monkeypox virus (MPXV) clade IIb prompted widespread use of the modified vaccinia Ankara-Bavarian Nordic (MVA-BN) vaccine which conferred partial protection and contributed to outbreak control. In 2024, the emergence and regional expansion of MPXV clade Ib in central Africa raised new public health concerns and prompted questions about the extent to which immunity elicited by previous clade IIb infection or vaccination confers cross-neutralising immunity against clade Ib. We aimed to assess neutralising and binding antibody responses to MPXV clades Ia, Ib, and IIb after infection or vaccination. METHODS:). Vaccina virus (VACV) was included as a reference control for vaccine-induced immunity. For ELISA and neutralisation assays, thresholds of positivity were defined as the median plus 3 SDs of values obtained from individuals in the control cohort. FINDINGS/RESULTS:1·02 [1·02-1·30] for clade Ia, 1·00 [1·00-1·00] for clade Ib, and 1·20 [IQR 1·00-1·76] for clade IIb). At the antigen level, A35-targeted antibodies bound less efficiently to clade I A35 variants compared with clade IIb. INTERPRETATION/CONCLUSIONS:Humoral immunity elicited by historical or contemporary smallpox vaccination was associated with little neutralising activity across MPXV clades. Of note, previous MPXV clade IIb infection induced cross-reactive antibody binding but low-magnitude neutralising activity against clade Ib. Although additional immune mechanisms could contribute to protection, these findings highlight important constraints in antibody-mediated cross-clade immunity and emphasise the need for vaccines and antibody-based countermeasures that address antigenic divergence among orthopoxviruses. FUNDING/BACKGROUND:Yale University, Stavros Niarchos Foundation Institute for Global Infectious Disease, Icahn School of Medicine at Mount Sinai, US National Institutes of Health, and US National Institute of Allergy and Infectious Diseases.

BACKGROUND:Although both maternal respiratory syncytial virus (RSV) prefusion F vaccination (RSVpreF) and infant nirsevimab immunization have been approved for the prevention of RSV lower respiratory tract infections, the 2 have not been evaluated in a single study, and their sequential administration has not been studied systematically. METHODS:We performed a prospective, randomized, open-label, phase 4 study at 8 US sites of mother-infant pairs randomized 1:1:1:1 during pregnancy: maternal RSVpreF vaccine alone, maternal RSVpreF vaccine/infant nirsevimab at birth, maternal RSVpreF vaccine/infant nirsevimab at 3 months, or infant nirsevimab alone at birth. We are following the mother-infant pairs for 12 months to ascertain safety, infant tolerability, and the magnitude and durability of RSV-A and -B neutralizing antibodies (nAbs). We report interim data from September 19, 2024, to May 15, 2025, including 4-month infant follow-up. RESULTS:In total, 181 mothers were enrolled. Both products alone and in combination were safe. No related serious adverse events were observed in mothers or infants. Nirsevimab was well tolerated, and all local and systemic reactogenicity was mild to moderate in severity. RSVpreF vaccination boosted maternal RSV-A nAb titers 17.35-fold at the time of delivery, and titers were durable through 3 months postdelivery. The geometric mean transfer ratio of RSV-A nAbs was higher than 1.3 and similar across groups. RSV nAbs were highly elevated in infants at 6 weeks and 3 months, irrespective of group, with modest differences in waning. CONCLUSIONS:Maternal RSVpreF vaccine and infant nirsevimab administration, either alone or in combination, were safe and provided high RSV nAb titers in infants through interim follow-up.

The 2022 global outbreak of clade IIb mpox represented a turning point in public health's handling of poxviruses. The primary vaccine available for the prevention of mpox is modified vaccinia Ankara from Bavarian-Nordic (MVA-BN). We previously reported a nondurable and low-avidity antibody response against mpox elicited by MVA-BN. In this study, we expanded upon this knowledge by employing a microneutralization assay to measure monkeypox virus (MPXV) neutralizing titers and a multiplexed immunoassay to assess IgG titers and avidity against eight MPXV antigens and two vaccinia antigens. Through a machine learning analysis, we uncovered that MVA-BN vaccinees without prior smallpox vaccination largely return to a baseline seroprofile within a year of immunization. Notably, we identified a discrete population within this group that mounted a robust neutralizing antibody response associated with a longer dosing interval during the MVA-BN primary series. Furthermore, we found that boosting with a third dose of MVA-BN increases IgG avidity against certain MPXV antigens, as part of a booster-specific seroprofile. These findings provide critical insights into optimizing immune responses through MVA-BN boosters, presenting a potential approach to addressing the limited MPXV-specific immunity observed following the primary series.

BACKGROUND:A next-generation, live-attenuated yellow fever vaccine, vYF, was developed in Vero cells to improve vaccine supply and availability. The safety of and immune response to vYF as compared with those of the licensed yellow fever vaccine, YF-VAX, are unclear. METHODS:In this year 1 interim analysis of a phase 2, observer-blinded, randomized, active-controlled trial, we randomly assigned healthy adults 18 to 60 years of age in a 2:1 ratio to receive vYF or YF-VAX as a single vaccine injection on day 1. Neutralizing antibody titers were measured on day 29, month 6, and year 1. The primary analysis focused on the per-protocol population, which included participants with no history of yellow fever infection or vaccination and with no protocol deviations. Noninferiority would be shown if the lower limit of the two-sided 95% confidence interval of the between-group difference in the percentage of participants with seroconversion was greater than -5 percentage points on day 29. RESULTS:A total of 568 participants were enrolled: 382 in the vYF group and 186 in the YF-VAX group; 329 and 156 participants, respectively, were included in the per-protocol population for the noninferiority analysis. Seroconversion by day 29 occurred in 99.7% of participants receiving vYF and 99.4% of those receiving YF-VAX (difference, 0.3 percentage points; 95% confidence interval, -1.2 to 3.2, which met the criterion for noninferiority). Neutralizing antibody geometric mean titers were similar in the two vaccine groups, peaking on day 29 (in the vYF group, 1:2654 among participants with no history of yellow fever infection or vaccination and 1:1312 among participants with a history of yellow fever infection or vaccination; in the YF-VAX group, 1:3147 and 1:1079, respectively), then decreasing through 1 year after vaccination (in the vYF group, 1:401 among participants with no history of yellow fever infection or vaccination and 1:490 among participants with a history of yellow fever infection or vaccination; in the YF-VAX group, 1:548 and 1:646, respectively). No major safety concerns were identified. The safety profiles were similar in the two vaccine groups: solicited adverse events were reported by 208 of 367 participants (56.7%) in the vYF group and 113 of 185 participants (61.1%) in the YF-VAX group, and unsolicited adverse events were reported by 99 of 379 participants (26.1%) and 39 of 186 participants (21.0%), respectively. CONCLUSIONS:In this trial, vYF had immunogenicity and safety profiles similar to those of YF-VAX. (Funded by Sanofi; ClinicalTrials.gov number, NCT04942210.).

Snow Mountain Virus (SMV), the prototype of genogroup II and genotype II Norovirus (NoV), was used in human challenge studies to examine the infectivity, pathogenicity, and immune response to NoV. Clinical and laboratory data from two previously completed SMV human challenge trials using two different inocula (primary and secondary) were analyzed to compare the infectivity, illness, viral shedding, and serum IgG conversion. The primary and secondary SMV inocula were sequenced for detecting single nucleotide mutations. Of 15 subjects challenged with the primary inoculum between 2000 and 2002, nine were infected, and seven presented with acute gastroenteritis. Of 33 subjects challenged with the secondary inoculum between 2016 and 2018, 25 were infected, and nine presented with acute gastroenteritis. There were no statistically significant differences in overall infection and illness rates between subjects challenged with the primary inoculum versus the secondary inoculum. However, subjects infected with the primary inoculum experienced more severe clinical symptoms of acute gastroenteritis, showing higher severity scores (6.00 vs. 2.94, p = 0.003) compared with those infected with the secondary inoculum. We also observed that infection with the secondary inoculum resulted in longer viral shedding compared with the primary inoculum. Partial sequencing of the SMV genome identified three mutations in both inocula. Understanding the differences between these two SMV inocula is critical for NoV vaccine evaluation and using a less pathogenic inoculum for a vaccine trial will require more participants to meet the target reduction in illness when evaluating the efficacy of candidate vaccines.

SARS-CoV-2 infection is associated with platelet hyperreactivity and increased rates of arterial and venous thrombosis. SARS-CoV-2 mutations have resulted in several variants with differences in transmissibility, infectivity, and patient outcomes. This study investigates the effects of the ancestral strain of SARS-CoV-2 (WA1) and two variants of concern, Delta and Omicron, on the human megakaryocyte (MK) phenotype and transcriptome. Human CD34⁺-derived MKs were incubated with WA1, Delta or Omicron SARS-CoV-2 variants for 24 hours. MK activation markers were measured under resting and thrombin-stimulated conditions. RNA-seq and cytokine release in response to the viruses were assessed. Plasma cytokines were measured in hospitalized COVID-19 patients. Treatment of MKs with WA1, Delta or Omicron variants of SARS-CoV-2 resulted in similar increases in classical activation markers. However, SARS-CoV-2 variants mediated distinct transcriptomic changes. Across variants, 60 genes overlapped, including CXCL8. Consistent with transcriptomic changes, SARS-CoV-2-incubated MKs secreted significantly elevated levels of IL-8. Among hospitalized COVID-19 patients, plasma IL-8 levels were highest in COVID-19 patients who subsequently experienced thrombotic events or died. In conclusion, WA1, Delta, and Omicron similarly induce classical MK activation responses while mediating distinct transcriptomic changes. Increased IL-8 levels may serve as a biomarker to inform platelet hyperreactivity and thrombotic events associated with COVID-19.

BACKGROUND AND OBJECTIVE/OBJECTIVE:We describe the kinetics of maternally derived antibodies in infants in the first 6 months of life following 2- or 3-dose maternal vaccination during pregnancy or postpartum. METHODS:This prospective, multicenter cohort study enrolled infants born to mothers vaccinated with 2- (n = 280) or 3-dose (boosted) monovalent messenger RNA vaccines in pregnancy (n = 202) or to mothers vaccinated postpartum (n = 36) from July 2021 to January 2022. Binding (immunoglobulin G to S and receptor-binding domain), pseudovirus, and live neutralizing antibody (nAb) geometric mean titers (GMTs) to vaccine and Omicron BA.1/BA.5 strains were measured at birth and 2 and 6 months of age. Antibody half-life and the effect of maternal or infant COVID-19 infection were assessed. RESULTS:Significantly higher GMTs of binding antibody and nAb to all antigens were present at birth and 2 months in infants of boosted mothers (P < .01) and higher titers to the vaccine strain, but not Omicron BA.1 and BA.5, persisted up to 6 months of age in infants of boosted mothers compared with the other groups (P < .01). Higher infant antibody titers at delivery and 6 months of age were associated with a booster dose during pregnancy and maternal prenatal and infant COVID-19 infection. Maternal infection status or vaccine regimen did not influence the half-life of infant antibodies. CONCLUSIONS:A maternal COVID-19 booster in pregnancy results in significantly higher functional antibody titers in infants compared with 2 doses in pregnancy or postpartum. High titers at birth and maternal hybrid immunity result in persistently elevated titers in infants for 6 months.

BACKGROUND:Mucosal immunity plays a critical role in preventing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and replication. Understanding the capacity of coronavirus disease 2019 (COVID-19) vaccines to elicit both mucosal and systemic antibodies could help optimize vaccination strategies. METHODS:We conducted an open-label, phase 1/2 adaptive-design clinical trial to evaluate the safety and immunogenicity of COVID-19 immunizations. Healthy adults received 2 priming doses of mRNA-1273, a booster dose of mRNA-1273, and a second booster of bivalent (WA-1 and BA.4/BA.5) mRNA-1273.222. Adverse event data were collected. Serum and mucosal immunity were evaluated. RESULTS:One hundred six persons were enrolled. Thirty received all 4 study-related vaccine doses. All vaccines were well tolerated, with injection site pain, malaise, myalgias, and headache being the most frequently reported symptoms. Among those who received a second booster, 24 of 30 (80%) had serological evidence of SARS-CoV-2 infection. Following the second booster, increases in geometric mean binding and pseudovirus neutralization antibody titers to the ancestral strain and BA.1 and BA.5 variants were observed. Increases in mucosal immunoglobulin G and immunoglobulin A (IgA) antibodies in nasal and salivary samples were observed in both previously infected and infection-naive participants, although prior infection markedly boosted virus-specific mucosal IgA responses. CONCLUSIONS:The mRNA-1273.222 booster vaccine was safe and immunogenic and induced mucosal antibody responses in previously infected and infection-naive persons. CLINICAL TRIALS REGISTRATION/BACKGROUND:NCT04889209.