Doses Of Varicella-zoster Virus Vaccine Research Articles

Seroprevalence of Measles, Mumps, Rubella, and Varicella-Zoster Virus and Seroresponse to the Vaccinations in Adult Solid Organ Transplant Candidates.

Updating live vaccines such as measles, mumps, rubella, and varicella (MMRV) is an important step in preparing patients for solid organ transplant (SOT) to prevent morbidity from these preventable diseases. However, data for this approach are scarce. Thus, we aimed to describe the seroprevalence of MMRV and the efficacy of the vaccines in our transplant center. Pre-SOT candidates >18 y of age were retrospectively retrieved from SOT database in Memorial Hermann Hospital Texas Medical Center. MMRV serologies are routinely screened at the time of pretransplant evaluation. We divided patients into 2 groups: MMRV-positive group versus MMRV-negative group, patients with positive all MMRV serologies and with negative immunity to at least 1 dose of MMRV, respectively. A total of 1213 patients were identified. Three hundred ninety-four patients (32.4%) did not have immunity to at least 1 dose of MMRV. Multivariate analysis was conducted. Older age (odds ratio [OR]: 1.04) and liver transplant candidates (OR: 1.71) were associated with seropositivity. Previous history of SOT (OR: 0.54) and pancreas/kidney transplant candidates (OR: 0.24) were associated with seronegativity. Among 394 MMRV seronegative patients, 60 patients received 1 dose of MMR vaccine and 14 patients received 1 dose of varicella-zoster virus vaccine without severe adverse events. A total of 35% (13/37) of patients who had follow-up serologies did not have a serological response. A significant number of pre-SOT candidates were not immune to at least 1 dose of MMRV. This highlights the importance of MMRV screening and vaccinations pre-SOT. Postvaccination serological confirmation should be performed to evaluate the necessity for a second dose.

Immunogenicity of varicella zoster vaccine in pediatric liver transplantation.

Pediatric liver transplant (LT) candidates often miss complete varicella-zoster virus (VZV) vaccination before LT. We aimed to evaluate the immunogenicity of two doses of VZV vaccines in pediatric LT candidates younger than 2 years and persistence of its immunogenicity after LT. Patients aged 9-24 months were enrolled before LT. The first dose of VZV vaccine was given at 9 months, and the second dose was given at between 1 to 3 months later, and at least 4 weeks before LT. Varicella-zoster IgG (VZG) was used to detect immunoglobulin G antibodies to VZV and was reported as a test value (TV). A test value ≥ 0.9 was considered as seropositive. TV was measured at enrollment, 1 month after the first and the second dose of VZV vaccine, before LT, and 3 and 6 months after LT. Fourteen children were enrolled in this prospective cohort study. The median age at the first and the second dose of VZV vaccine was 11.5 months (IQR 9-12) and 13 months (IQR 12-33), respectively. The seroconversion rate was 66.7% (8/12) and 70% (7/10) after the first and second VZV vaccine doses, respectively. Seven of nine patients who underwent LT had two doses of VZV vaccine. Six patients were seropositive before LT, which persisted at 3 to 6 months after LT. Of two patients who received only one dose, TV was not detected after LT. The two doses of VZV vaccine appeared to be more immunogenic than one dose in pediatric LT candidates aged less than 2 years.

Seroprevalence survey for Varicella among healthcare workers and medical students in Italy

ABSTRACT Varicella is a potentially serious infectious disease caused by Varicella-Zoster Virus (VZV). In Italy childhood varicella vaccine have gradually introduced into national immunization program since 2003 and from 2017 a two-doses schedule has been stated nationally for all newborns and has become compulsory for school attendance. VZV exposures among healthcare workers (HCWs) and patients can be really dangerous and expensive. According to Centers of Disease Control and Italian national immunization plan health care, institutions should verify that all HCWs have clear evidence of immunity to VZV and should ensure that susceptible subjects will receive 2 doses of VZV vaccine. Currently, the vaccination of HCWs is not compulsory in Italy and the risk of varicella infection among these subjects is not well known. We evaluated the clinical records of 840 HCWs (256 male and 584 female) who underwent the annual occupational screening, from 1st January to 31st August 2018. HCWs were divided into three subgroups according to their age: 18–30, 31–40, and over 40 years old. We compared the mean values of IgG-specific antibodies between the age group through analysis of variance (ANOVA). A total of 784 (93.33%) HCWs were protected for VZV IgG antibodies level. There wasn’t a significant difference between male and female while was found between age group (P < 0.001). Protection levels for varicella are inadequate among HCWs. Despite the epidemiology of varicella in general population has changed with the implementation of the childhood varicella vaccination program transmission of VZV in hospitals is still a serious problem, so it is necessary to increase prevention activities in these settings, including vaccination.

Serological and T Cell Responses After Varicella Zoster Virus Vaccination in HIV-Positive Patients Undergoing Renal Dialysis.

Limited data on varicella zoster virus (VZV) vaccine responses are available in HIV-positive adults, especially among those with end-stage renal disease on dialysis or undergoing kidney transplantation (KT). Serological and T cell responses were analyzed using anti-VZV IgG titers, enzyme-linked immunosorbent assay and flow cytometric intracellular cytokine staining (ICS) in two HIV-positive kidney transplant candidates undergoing dialysis and receiving VZV immunization. The results were compared with two HIV-positive and two HIV-negative VZV-seropositive patients (two kidney transplant candidates and two kidney transplant recipients), and with one HIV-negative vaccinee. HIV-positive VZV-susceptible patients received two doses of VZV vaccine 12 weeks apart. No adverse events were reported. Serological data were indicative of immunological response in one patient and corresponded to T cell responses. The second patient showed only a transient increase in anti-VZV IgG titers, but reported positive CD4+ T cell responses that were maintained after KT. Positive T cell and serological responses were detected in both HIV-positive and HIV-negative controls. VZV vaccination appeared safe and effective in HIV-positive KT candidates. VZV-specific T cell immunity was detected among transplant candidates and after KT. The assessment of VZV-specific T cell immunity using flow cytometric ICS may be more reliable compared to serology in assessing responses to VZV vaccine in this group.

Increasing Immunization Coverage

In 1977, the American Academy of Pediatrics issued a statement calling for universal immunization of all children for whom vaccines are not contraindicated. In 1995, the policy statement "Implementation of the Immunization Policy" was published by the American Academy of Pediatrics, followed in 2003 with publication of the first version of this statement, "Increasing Immunization Coverage." Since 2003, there have continued to be improvements in immunization coverage, with progress toward meeting the goals set forth in Healthy People 2010. Data from the 2007 National Immunization Survey showed that 90% of children 19 to 35 months of age have received recommended doses of each of the following vaccines: inactivated poliovirus (IPV), measles-mumps-rubella (MMR), varicella-zoster virus (VZB), hepatitis B virus (HBV), and Haemophilus influenzae type b (Hib). For diphtheria and tetanus and acellular pertussis (DTaP) vaccine, 84.5% have received the recommended 4 doses by 35 months of age. Nevertheless, the Healthy People 2010 goal of at least 80% coverage for the full series (at least 4 doses of DTaP, 3 doses of IPV, 1 dose of MMR, 3 doses of Hib, 3 doses of HBV, and 1 dose of varicella-zoster virus vaccine) has not yet been met, and immunization coverage of adolescents continues to lag behind the goals set forth in Healthy People 2010. Despite these encouraging data, a vast number of new challenges that threaten continued success toward the goal of universal immunization coverage have emerged. These challenges include an increase in new vaccines and new vaccine combinations as well as a significant number of vaccines currently under development; a dramatic increase in the acquisition cost of vaccines, coupled with a lack of adequate payment to practitioners to buy and administer vaccines; unanticipated manufacturing and delivery problems that have caused significant shortages of various vaccine products; and the rise of a public antivaccination movement that uses the Internet as well as standard media outlets to advance a position, wholly unsupported by any scientific evidence, linking vaccines with various childhood conditions, particularly autism. Much remains to be accomplished by physician organizations; vaccine manufacturers; third-party payers; the media; and local, state, and federal governments to ensure dependable vaccine supply and payments that are sufficient to continue to provide immunizations in public and private settings and to promote effective strategies to combat unjustified misstatements by the antivaccination movement. Pediatricians should work individually and collectively at the local, state, and national levels to ensure that all children without a valid contraindication receive all childhood immunizations on time. Pediatricians and pediatric organizations, in conjunction with government agencies such as the Centers for Disease Control and Prevention, must communicate effectively with parents to maximize their understanding of the overall safety and efficacy of vaccines. Most parents and children have not experienced many of the vaccine-preventable diseases, and the general public is not well informed about the risks and sequelae of these conditions. A number of recommendations are included for pediatricians, individually and collectively, to support further progress toward the goal of universal immunization coverage of all children for whom vaccines are not contraindicated.

Humoral immunogenicity to measles, rubella, and varicella-zoster vaccines in biliary atresia children

To investigate the humoral immune response to measles, rubella, and varicella-zoster virus (VZV) vaccines in biliary atresia (BA) children before liver transplantation, we conducted the cross-sectional designed study. Fifty BA children (age, 3.6 ± 0.2 years; 24 girls) who had not yet received liver transplantation, and another 150 healthy controls (age, 4.0 ± 0.1 years; 78 girls) were recruited into this study to evaluate their primary humoral immune response to measles, rubella, and VZV vaccines. All of these BA children ( n = 50) and controls ( n = 150) received one dose of measles, one dose of measles–mumps–rubella (MMR), and one dose of VZV vaccine before our assessment. Serum samples were collected at least 1 month after the vaccination and serum immunoglobulin G (IgG) antibody to measles, rubella, and VZV were then determined by qualitative enzyme-linked immune-sorbent assay. The prevalence of seropositive rate of measles IgG antibody (84% vs. 96.7%; P = 0.002), rubella (82.0% vs. 98.7%; P < 0.001), and VZV (74% vs. 95.3%; P < 0.001) were significantly different between BA children and the controls after regular measles, MMR, and VZV vaccination before 2 years of age. In those BA children with seronegative VZV antibody after vaccination, two had VZV infection after the liver transplantation. This study indicated that humoral immunity to rubella, measles and VZV vaccines are significantly lower in BA children than the normal population by standard vaccine schedule.

Humoral and Cell‐Mediated Immune Responses in Children and Adults after 1 and 2 Doses of Varicella Vaccine

Humoral and cell-mediated immune responses to varicella-zoster virus (VZV) have been evaluated after 1 and 2 doses of live attenuated varicella vaccine, Oka strain, in several studies. One dose of varicella vaccine, however, elicits detectable immune responses that are low and, in some cases, may be insufficient for complete protection against the virus after the normal decline in humoral and cell-mediated immunity with time. In contrast, immune responses after 2 doses are significantly higher and approximate the levels seen after natural disease. These investigations of vaccine-induced immunity suggest that 2 doses of VZV vaccine will better achieve the goals of the VZV vaccination program, by reducing the VZV burden of disease in childhood and preventing accumulation of young adults who are susceptible to or only partially protected from varicella.

Immunogenicity of a two-dose regime of varicella vaccine in children with cancers.

Live-attenuated varicella vaccine is effective and safe in immunocompetent children. In this study, we assess the immunogenicity and adverse events following varicella vaccination in immunosuppressed cancer children. Varicella-zoster virus (VZV)-seronegative cancer children received two doses of live-attenuated VZV vaccine (Varilrix) in a span of 3 months. Patients with acute lymphoblastic leukaemia (ALL) were in the maintenance phase of chemotherapy, whereas those with solid tumours joined the study around 3-6 months from treatment discontinuation. VZV-specific cellular and humoral immune responses were measured before and after VZV vaccination. The median (range) age of the 17 patients was 4.4 yr (2.0-14.5). Thirteen had ALL, one had myelodysplastic syndrome and three had solid tumours. Following vaccination, the VZV-specific stimulation index (SI) increased from 1.7 (0.9-2.9) to 17.9 (5.9-36.0) (P < 0.001). Similarly, SI to phytohaemagglutinin mitogen increased from 1136 (499-1930) to 1714 (848-2518) (P = 0.028). There were also significant increases in CD4+ cells and CD4:CD8 ratio as well as a reduction in CD16/56+ cells in peripheral blood lymphocytes. Seroconversion rate to VZV was 19% after one dose and increased to 94% after the second dose of VZV vaccine. Serum VZV-specific IgG concentrations also increased significantly following two doses when compared with one dose of VZV vaccine (P = 0.0004). One subject developed possibly vaccine-related chickenpox with self-limiting hepatitis at 5 wk following vaccination. None of the patients developed herpes-zoster at a median (range) follow-up of 27.5 months (24.0-30.0). Non-immune cancer children can be effectively vaccinated against chickenpox at the defined period. However, the safety of chickenpox vaccine in these immunosuppressed children needs to be further studied.

Immunogenicity and reactogenicity of a single dose of live attenuated varicella vaccine and a booster dose of measles-mumps-rubella vaccine given concomitantly at 12 years of age.

Universal varicella-zoster virus (VZV) childhood vaccination is still debated, but adult chickenpox may be severe. It could be prevented by vaccination of seronegative adolescents. This study aimed to determine the feasibility of coadministration of a VZV vaccine and the measles-mumps-rubella (MMR) booster at 12 y of age. Guardians of 1231 12-y-old pupils where asked about the history of chickenpox in their children. 190 had no chickenpox history and 12 of 62 of them lacked VZV antibodies. Additional history-negative children were also recruited. 199 history-positive children received only MMR and 98 history-negative children received an MMR vaccine and a VZV vaccine. Serum samples were drawn before vaccination and after 8 weeks. Viral antibodies were measured by immunofluorescence (VZV) and enzyme-linked immunosorbent assays (VZV, MMR). All 184 history-positive children tested had VZV antibodies. 17/89 VZV-vaccinated and tested children (19%) lacked VZV antibodies before vaccination. 12 (71%) seroconverted after 1 dose. Cell-mediated immunity (CMI) against varicella was tested in 3/5 children who did not seroconvert after 1 dose of VZV vaccine. They seroconverted after a second dose and had measurable CMI. VZV vaccination did not affect the MMR response and there were no severe side-effects. A history of varicella infection, as reported by the guardian, is reliable, but a negative history was incorrect in 81% of the cases. This population of 12-y-old children may require 2 doses of VZV vaccine, at least when given simultaneously with the MMR vaccine.

Immunization of the elderly and patients with collagen vascular diseases with live varicella vaccine and use of varicella skin antigen.

Elderly subjects and patients with collagen vascular diseases were immunized with a live varicella vaccine to assess the vaccine's potential for preventing herpes zoster. An improved varicella-zoster virus (VZV) skin test antigen was then used to assess cell-mediated immunity to VZV. The antigen was prepared from culture fluid of VZV-infected cells and had far less protein content than crude antigen prepared by sonication of infected cells. In 11 of 12 patients with ophthalmic zoster and 17 of 21 with dermal zoster, the skin reaction was negative at the beginning of the disease but became positive later. After two doses of VZV vaccine, 8 of 12 elderly subjects (greater than 60 years old) and 4 of 6 patients with collagen vascular diseases, who were VZV-skin test negative but purified protein derivative tuberculin test-positive, became VZV skin test-positive.