Influenza surveillance in a cohort of HIV-infected children and adolescents immunized against seasonal influenza

Immune reconstitution and vaccination outcome in HIV-1 infected children: present knowledge and future directions

Current evidence on routine immunization of HIV-1 infected children point out the need for a special vaccine schedule in this population. However, optimal strategies for identifying individuals susceptible to infections, and then offering them sustained protection through appropriate immunization schedule, both in terms of timing and number of vaccine doses, still remain to be elucidated. Understanding the degree of immune recovery after HAART initiation is important in guiding administration of routine vaccination in HIV-1 infected children. Although quantitative measures (e.g., CD4+ T-cell counts and immunoglobulin levels) are frequently performed to evaluate immune parameters, these measures do not fully mirror functional immune recovery. Here, we will review the status of single mandatory and recommended vaccines for HIV-1 infected children in relation to immune recovery after HAART initiation with the aim of identifying new means to help design personalized vaccine schedules for this population.

Short communication: immunogenicity of an inactivated influenza vaccine and postvaccination influenza surveillance in HIV-infected and noninfected children and adolescents

Individuals infected with HIV are at higher risk for severe cases of seasonal influenza infection and should receive annual doses of vaccine. Our objectives were to evaluate the immunogenicity of an influenza vaccine in 37 HIV-infected patients (HIV group) compared to 29 uninfected individuals (control group) and to carry out a clinical and virological surveillance of influenza during a 6-month follow-up. Both groups received the vaccine recommended for the southern hemisphere in 2008. Antibody responses to antigens H1N1, H3N2, and B were measured in blood samples at vaccination (T0) and after 1 month (T1). Influenza surveillance was performed by weekly telephone calls for a follow-up period of 6 months. Nasal washes were taken from subjects with respiratory symptoms. The direct immunofluorescence assay in house polymerase chain reaction (PCR) and real-time PCR were used for the detection of different respiratory viruses. The median age of the participants was 13.3 years (sd = 2.2) and 12.1 years (sd = 1.3) for the HIV group and control group, respectively. One month after vaccination (T1), both groups showed significant increases in the antibody geometric mean titers (GMTs) for all antigens. However, healthy controls showed higher values for antigens A/H1N1 and A/H3N2 (p = 0.002 and 0.001, respectively). There was a higher increase in the percentage of HIV-uninfected subjects with protective A/H1N1 antibodies (96.6%) compared to HIV-infected vaccinees (67.6%) at T1 (p = 0.004). Rhinovirus (27.7%) and coronavirus (22.5%) were the most prevalent agents identified in HIV-infected individuals. In the control group, the viruses most frequently found were rhinovirus (24.2%) and adenovirus (21.2%). The seroprotection rate for the H1N1 antigen was higher in the control group, which also showed a greater increase in GMTs for H1N1 and H3N2 antigens after immunization. Viral agents were identified in 39/60 (65%) episodes of respiratory infections from the HIV-infected group and in 17/32 episodes (53.1%) from the control group (p = 0.273).

Long-term immunogenicity after one and two doses of a monovalent MF59-adjuvanted A/H1N1 Influenza virus vaccine coadministered with the seasonal 2009-2010 nonadjuvanted Influenza virus vaccine in HIV-infected children, adolescents, and young adults in a randomized controlled trial

Few data are available on the safety and long-term immunogenicity of A/H1N1 pandemic influenza vaccines for HIV-infected pediatric patients. We performed a randomized controlled trial to evaluate the safety and long-term immunogenicity of 1 versus 2 doses of the 2009 monovalent pandemic influenza A/H1N1 MF59-adjuvanted vaccine (PV) coadministered with the seasonal 2009-2010 trivalent nonadjuvanted influenza vaccine (SV) to HIV-infected children, adolescents, and young adults. A total of 66 HIV-infected patients aged 9 to 26 years were randomized to receive one (group 1) or two (group 2) doses of PV coadministered with 1 dose of SV. The main outcome was the seroconversion rate for PV at 1 month. Secondary outcomes were the geometric mean titer ratios and the seroprotection rates at 1 month for all vaccines, seroconversion rates at 1 month for SV, and longitudinal changes of antibody titers (ABTs) at 1, 2, 6, and 12 months for all vaccines. Groups 1 and 2 had similar CD4 counts and HIV RNA levels during the study. The seroconversion rate for PV was 100% at 1 month in both groups. ABTs for PV were high during the first 6 months and declined below seroprotection levels thereafter. Longitudinal changes in ABTs were similar in groups 1 and 2 for both PV and SV. The side effects of vaccination were mild and mostly local. In HIV-infected children, adolescents, and young adults, the immune response triggered by a single dose of PV was similar to that obtained with a double dose and was associated with long-term antibody response.

The immunogenicity of a novel A (H1N1) vaccine in HIV-infected children

BACKGROUND

In October 2009, the United Kingdom Department of Health recommended vaccination of high-risk groups, including children with HIV, with a novel, oil-in-water AS03(B) adjuvanted Influenza A (H1N1) vaccine (Pandemrix). There were no published data available regarding the immunogenicity of this vaccine in such children.

OBJECTIVES

This study evaluated the immunogenicity of the adjuvanted Influenza A (H1N1) vaccine in HIV-infected children immunised according to national recommendations and assessed the impact of vaccination on individual CD4 counts and HIV viral loads.

METHODS

HIV-infected children attending outpatient appointments between 01 November and 31 December 2009 were offered two doses of H1N1 vaccine three weeks apart and a blood test before and 3 weeks after the second dose of vaccine. Serum antibody responses were determined by a haemagglutination inhibition (HAI) assay using standard methods.

RESULTS

Of the 39 children recruited for vaccination, 31 (median age 11.2, range 3.0-17.9 years) received both doses of vaccine and provided pre- and post-vaccination blood samples. Eight children (26%) had baseline HAI titres ≥ 1:32. After vaccination, 29 children (94%, 95% CI, 78.6-99.2%) had HAI titres ≥ 1:32 (seroprotection), of whom 27 (87.1%, 95% CI, 70.1-96.4%) had also had a four-fold rise in titres (seroconversion). In the univariate analysis, post-vaccination geometric mean titres (GMTs) were higher among the 21 children receiving highly active anti-retroviral therapy compared with the 10 treatment-naïve children (GMT 406 [95% CI 218-757] vs. 128 [49-336]; P=0.035), but this was no longer statistically significant when adjusted for prevaccine GMTs. There was no significant impact of vaccination on CD4+ T cell count or HIV viral load.

CONCLUSION

The AS03(B)-adjuvanted pandemic Influenza A (H1N1) vaccine is highly immunogenic and appears to be safe in HIV-infected children.

Influenza vaccine for pregnant women in resource-constrained countries: a review of the evidence to inform policy decisions

Seasonal influenza is responsible for three to five million severe cases of disease annually, and up to 500,000 deaths worldwide. Pregnant women and infants suffer disproportionately from severe outcomes of influenza. The excellent safety profile and reliable immunogenicity of inactivated influenza vaccine support WHO recommendations that pregnant women be vaccinated to decrease complications of influenza disease during pregnancy. Nevertheless, influenza vaccine is not routinely used in most low-and middle-income countries and is not widely used in pregnant women worldwide. Two recent prospective, controlled trials of maternal influenza vaccination in Bangladesh and US Native American reservations demonstrated that inactivated influenza vaccine given to pregnant women can decrease laboratory-confirmed influenza virus infection in their newborn children. These studies support consideration of the feasibility of targeted influenza vaccine programs in resource-constrained countries. Platforms exist for the delivery of influenza vaccine to pregnant women worldwide. Even in the least developed countries, an estimated 70% of women receive antenatal care, providing an opportunity for targeted influenza vaccination. Challenges to the introduction of maternal influenza vaccination in resource-constrained countries exist, including issues regarding vaccine formulation, availability, and cost. Nonetheless, maternal influenza vaccination remains an important and potentially cost-effective approach to decrease influenza morbidity in two high-risk groups - pregnant women and young infants.