Modelling the linkage between influenza infection and cardiovascular events via thrombosis.

There is a heavy burden associated with influenza including all-cause hospitalization as well as severe cardiovascular and cardiorespiratory events. Influenza associated cardiac events have been linked to multiple biological pathways in a human host. To study the contribution of influenza virus infection to cardiovascular thrombotic events, we develop a dynamic model which incorporates some key elements of the host immune response, inflammatory response, and blood coagulation. We formulate these biological systems and integrate them into a cohesive modelling framework to show how blood clotting may be connected to influenza virus infection. With blood clot formation inside an artery resulting from influenza virus infection as the primary outcome of this integrated model, we demonstrate how blood clot severity may depend on circulating prothrombin levels. We also utilize our model to leverage clinical data to inform the threshold level of the inflammatory cytokine TNFα which initiates tissue factor induction and subsequent blood clotting. Our model provides a tool to explore how individual biological components contribute to blood clotting events in the presence of influenza infection, to identify individuals at risk of clotting based on their circulating prothrombin levels, and to guide the development of future vaccines to optimally interact with the immune system.

Cost-effectiveness of alternate strategies for childhood immunization against meningococcal disease with monovalent and quadrivalent conjugate vaccines in Canada.

BACKGROUND: Public health programs to prevent invasive meningococcal disease (IMD) with monovalent serogroup C meningococcal conjugate vaccine (MCV-C) and quadrivalent meningococcal conjugate vaccines (MCV-4) in infancy and adolescence vary across Canadian provinces. This study evaluated the cost-effectiveness of various vaccination strategies against IMD using current and anticipated future pricing and recent epidemiology. METHODS: A cohort model was developed to estimate the clinical burden and costs (CAN$2014) of IMD in the Canadian population over a 100-year time horizon for three strategies: (1) MCV-C in infants and adolescents (MCV-C/C); (2) MCV-C in infants and MCV-4 in adolescents (MCV-C/4); and (3) MCV-4 in infants (2 doses) and adolescents (MCV-4/4). The source for IMD incidence was Canadian surveillance data. The effectiveness of MCV-C was based on published literature. The effectiveness of MCV-4 against all vaccination regimens was assumed to be the same as for MCV-C regimens against serogroup C. Herd effects were estimated by calibration to estimates reported in prior analyses. Costs were from published sources. Vaccines prices were projected to decline over time reflecting historical procurement trends. RESULTS: Over the modeling horizon there are a projected 11,438 IMD cases and 1,195 IMD deaths with MCV-C/C; expected total costs are $597.5 million. MCV-C/4 is projected to reduce cases of IMD by 1,826 (16%) and IMD deaths by 161 (13%). Vaccination costs are increased by $32 million but direct and indirect IMD costs are projected to be reduced by $46 million. MCV-C/4 is therefore dominant vs. MCV-C/C in the base case. Cost-effectiveness of MCV-4/4 was $111,286 per QALY gained versus MCV-C/4 (2575/206 IMD cases/deaths prevented; incremental costs $68 million). CONCLUSIONS: If historical trends in Canadian vaccines prices continue, use of MCV-4 instead of MCV-C in adolescents may be cost-effective. From an economic perspective, switching to MCV-4 as the adolescent booster should be considered.

Safety and immunogenicity of two doses of quadrivalent meningococcal conjugate vaccine or one dose of meningococcal group C conjugate vaccine, both administered concomitantly with routine immunization to 12- to 18-month-old children.

OBJECTIVES: To describe the immunogenicity and safety of a two-dose series of a quadrivalent meningococcal (serogroups A, C, Y and W) polysaccharide diphtheria toxoid conjugate vaccine (MenACYW-D) administered to toddlers. METHODS: Children were randomly assigned (1:1) at study entry to receive MenACYW-D at 12 and 18 months of age (group 1; n=61) or meningococcal serogroup C conjugate vaccine (MCC) at 12 months of age (group 2; n=62). All received routine childhood immunizations. A, C, Y and W antibody titres were measured in group 1 before and one month after the 18-month MenACYW-D vaccination and were measured in group 2 at one and seven months post-MCC vaccination. Antibodies elicited by diphtheria and tetanus toxoids, and acellular pertussis vaccine adsorbed combined with inactivated poliomyelitis vaccine and Haemophilus influenzae b conjugate (DTaP-IPV-Hib) vaccine coadministered at the 18-month vaccination were measured one month later. Safety data were collected. RESULTS: At 19 months of age, ≥96% in group 1 achieved protective titres for the four meningococcal serogroups after dose 2; 67% in group 2 exhibited protective titres against serogroup C 28 days after MCC vaccination at 12 months of age, declining to 27% seven months later. DTaP-IPV-Hib elicited high antibody concentrations/titres in groups 1 and 2, consistent with historical values. The safety profiles after each dose generated no unexpected safety signals; no serious adverse events were related to vaccination. DISCUSSION: A two-dose series of MenACYW-D given concomitantly with a DTaP-IPV-Hib booster dose at 18 months of age demonstrated a good immunogenicity and safety profile. A two-dose series of MenACYW-D can be used as an alternative to one dose of MCC and provides protection against additional serogroups (NCT ID: NCT01359449).

OBJECTIFS: Décrire l'immunogénicité et l'innocuité d'une série de deux doses du vaccin polysaccharadique conjugué quadrivalent contre le méningocoque (des sérogroupes A, C, Y et W) et l'anatoxine diphtérique (Men-ACYW-D) administrée aux tout-petits. MÉTHODOLOGIE: En début d'étude, les enfants ont été répartis au hasard (1:1) entre l'administration du vaccin Men-ACYW-D à 12 et 18 mois (groupe 1; n=61) ou du vaccin conjugué contre le méningocoque de sérogroupe C (Men-C-C) à 12 mois (groupe 2; n=62). Tous ont reçu les vaccins systématiques pour les enfants. Les chercheurs ont mesuré les titres d'anticorps A, C, Y et W dans le groupe 1 avant et un mois après l'administration du vaccin Men-ACYW-D à 18 mois et dans le groupe 2 un et sept mois après l'administration du vaccin Men-C-C. Un mois plus tard, ils ont mesuré les anticorps induits par les anatoxines diphtérique et tétanique et par le vaccin adsorbé contre la coqueluche acellulaire combiné au vaccin inactivé contre la poliomyélite et au vaccin conjugué contre l'Haemophilus influenzae de type b (DCaT-VPI- Hib) coadministrés lors du vaccin de 18 mois. Ils ont colligé des données d'innocuité. RÉSULTATS: À 19 mois, au moins 96 % des enfants du groupe 1 avaient des titres protecteurs contre les quatre sérogroupes du méningocoque après la dose 2, tandis que 67 % de ceux du groupe 2 présentaient des titres protecteurs contre le sérogroupe C 28 jours après le vaccin Men-C-C à 12 mois, reculant à 27 % sept mois plus tard. Le vaccin DCaT-VPI-Hib conférait de fortes concentrations et titres d'anticorps dans les groupes 1 et 2, conformément aux valeurs antérieures. Les profils d'innocuité après chaque dose ne s'associaient à aucun signe d'innocuité inattendu, et aucun événement indésirable grave n'était lié à la vaccination. EXPOSÉ: Une série de deux doses du vaccin Men-ACYW-D administrée en même temps que la dose de rappel du DCaT-VPI-Hib à 18 mois présente un bon profil d'immunogénicité et d'innocuité. Elle peut remplacer une dose du vaccin Men-C-C et conférer une protection contre des sérogroupes supplémentaires (ID NCT : NCT01359449).