Assessments of plasma HIV RNA and CD4 cell counts after combined Pneumovax and tetanus toxoid vaccination: no detectable increase in HIV replication 6 weeks after immunization

Global strategies to prevent bacterial pneumonia in adults with HIV disease

We examined the peer-reviewed literature on the burden of bacterial pneumonia and the effectiveness of interventions for its prevention among HIV-infected adults in developed and developing countries. Bacterial pneumonia rates were up to 25-fold higher among HIV-infected adults than in the general community, with rates increasing as CD4+ T-cell count decreases. In developed countries, cohort studies showed that highly active antiretroviral therapy (HAART) had the most consistent effect on reducing pneumonia. In a prospective cohort and case-control studies from these regions, pneumococcal polysaccharide vaccine reduced pneumococcal disease in certain subgroups, particularly those with higher CD4+ T cells/microL. In patients with fewer than 200 CD4+ T cells/microL, antimicrobial prophylaxis was usually effective in reducing pneumonia. In sub-Saharan Africa, randomised controlled trials concluded that co-trimoxazole prophylaxis decreased rates of bacterial pneumonia, but pneumococcal polysaccharide vaccine prevented neither pneumonia nor invasive pneumococcal disease. Although not yet fully evaluated in Africa, based on experience in industrialised nations, use of HAART in Africa may have substantial potential to prevent bacterial pneumonia.

Viral load response to a pneumococcal conjugate vaccine, polysaccharide vaccine or placebo among HIV-infected patients

We determined the HIV viral load in 66 adults randomly assigned to receive pneumococcal immunization with one or two doses of protein conjugate vaccine, one dose of polysaccharide vaccine, one dose of each, or placebo. Second doses were given 8 weeks after the first. Mean baseline viral load and CD4 cell count were 3.41 copies/ml (log10) and 457 cells/microl, respectively. We found no change in viral load during 24 weeks of follow-up for any vaccine or combination of vaccines or placebo.

Reimmunization with 23-valent pneumococcal vaccine for patients infected with human immunodeficiency virus type 1: clinical, immunologic, and virologic responses

We determined the immunogenicity and safety of reimmunization with the 23-valent polysaccharide pneumococcal vaccine in patients infected with human immunodeficiency virus type 1 (HIV-1). Patients immunized >5 years earlier (initially within 1 year of HIV-1 seroconversion) were randomized to receive vaccine (n=57) or placebo (n=30). Persons with recent HIV-1 seroconversion (n=14) were immunized for the first time. Preimmunization levels of capsule-specific immunoglobulin G were similar in all groups. Reimmunized patients showed a significantly lower frequency and magnitude of antibody responses compared with persons with recent HIV-1 seroconversion. Reimmunized patients did not show adverse virologic or immunologic changes, but some reported local discomfort (15%) or fever (8%). Thus, the limited responses after reimmunization of HIV-1-infected patients with the current 23-valent vaccine mandates the need for a more effective reimmunization schedule, more immunogenic vaccines, or other behavioral and therapeutic interventions.

Immunologic and virologic response after tetanus toxoid booster among HIV-1- and HIV-2-infected Senegalese individuals

Twelve HIV-1-infected, nine HIV-2-infected patients and eight HIV-negative subjects were given a 40IU booster dose of tetanus toxoid (TT). Blood was collected on days 0, 7 and 30 after immunization. Changes in HIV-1 or HIV-2 RNA load were evaluated by nested PCR. TT-IgG antibody levels were quantified by ELISA. CD4 cell counts as well as activation, memory and maturation markers of T lymphocyte subsets were determined by flow cytometry. The induction of apoptosis was investigated using 7-aminoactinomycin D (AAD) and propidium iodide (PI) staining. Proliferative responses to TT and pokeweed mitogen (PWM) were determined by the level of [(3)H] thymidine incorporation. Seven and 30 days after immunization, there was no detectable increase in HIV-1 or HIV-2 plasma load. There were also no changes in CD4 cell counts, CD69, HLA-DR and memory CD45RO or naive CD45RA antigens. Immunization did not increase the spontaneous apoptosis of peripheral blood mononuclear cells (PBMCs), CD4+ and CD8+ T cells subsets neither in controls nor in HIV-infected patients. Similarly, apoptosis induced in vitro by PWM or by the specific TT recall antigen did not vary during the study period. The proliferative response to PWM and to the TT recall antigen was decreased both in HIV-1- and HIV-2-infected patients compared to HIV-negative controls. Immunization significantly increased the TT-IgG levels in healthy controls and in HIV-infected patients. However, the anti-TT-IgG response, as measured by the fold-increase index between days 0 and 30, was significantly higher in healthy controls than in HIV-1- (P=0.036) and HIV-2-infected patients (P=0.003). In conclusion, we found no deleterious immunologic or virologic effect was detected in healthy HIV-1- and HIV-2-infected individuals after antigenic challenge with a TT booster. However, the response to TT vaccination was lower in HIV-1- and in HIV-2-infected individuals than in healthy HIV-negative controls.

Influenza vaccination of HIV-1-positive and HIV-1-negative former intravenous drug users

The immunogenicity of an anti-influenza vaccine was assessed in 409 former intravenous drug user volunteers and its effect on the levels of HIV-1 RNA, proviral DNA and on CD4+ lymphocyte counts in a subset HIV-1-positive subjects was measured. HIV-1-positive individuals (n = 72) were divided into three groups on the basis of their CD4+ lymphocyte counts, while the 337 HIV-1-negative participants were allocated into group four. Haemagglutination inhibiting (HI) responses varied from 45.8 to 70% in the HIV-1-positive subjects and were significantly higher in group four (80.7% responses to the H1N1 strain, 81.6% to the H3N2 strain, and 83% to the B strain). The percentage of subjects with HI protective antibody titres (> or = 1:40) increased significantly after vaccination, especially in HIV-1 uninfected subjects. Immunization caused no significant changes in CD4+ counts and in neither plasma HIV-1 RNA nor proviral DNA levels. Therefore, vaccination against influenza may benefit persons infected by HIV-1.

Rethinking recommendations for use of pneumococcal vaccines in adults

Streptococcus pneumoniae remains a major cause of disease worldwide; the emergence of antibiotic-resistant strains emphasizes the importance of disease prevention by use of vaccines. Recent studies have provided information that is useful for the evaluation of current vaccine recommendations. Recommendations target most people who are at high risk for invasive pneumococcal disease. However, higher risk has also been identified for African Americans and smokers, but these groups are not specifically targeted by current recommendations. The vaccine is effective against invasive disease in immunocompetent people, although studies in immunocompromised subjects have found few subgroups in which the vaccine appears to be effective. Questions with regard to optimal timing and indications for revaccination remain a challenge, because the duration of protection and effectiveness of revaccination remain unknown. New pneumococcal vaccines appear promising but will need to be tested against the performance of the polysaccharide vaccine. Improving delivery of the currently available pneumococcal polysaccharide vaccine to adults who will benefit should be a high priority.

The prevention of pneumococcal disease by vaccines: promises and challenges

This article reviews the epidemiology of pneumococcal disease and the current data on pneumococcal vaccine efficacy, discusses promising new data regarding development of new protein-conjugate pneumococcal vaccines, and addresses controversies surrounding the widespread population use of these vaccines. Armed with these data, physicians, nurses, third party payers, and health care systems should develop systems and eliminate unintentional barriers so as to achieve widespread use of these life-saving vaccines. As history has demonstrated to us, control of pneumococcal disease is highly unlikely to occur from heavy investments in newer and ever more expensive antibiotics, as opposed to better methods of preventing disease through the rational and widespread population use of vaccines.

Pneumococcal disease among human immunodeficiency virus-infected persons: incidence, risk factors, and impact of vaccination

To determine the factors associated with pneumococcal disease (pneumococcal pneumonia or invasive disease) and the impact of pneumococcal vaccine in HIV-infected persons, we analyzed patient data collected by the Adult and Adolescent Spectrum of HIV Disease Project for person-time between January 1990 and December 1998. Among 39,086 persons with 71,116 person-years (py) of observation, 585 episodes of pneumococcal disease were diagnosed (incidence, 8.2 episodes per 1000 py). Factors associated with an increased risk for pneumococcal disease (P < .05) included injection drug use (adjusted relative risk [RR], 1.5) and blood transfusion (RR, 2.0) as the mode of HIV transmission (referent, male-male sex); black race/ethnicity (RR, 1.5; referent, white race); history of acquired immunodeficiency syndrome (AIDS)-defining opportunistic illness (RR, 2.1); a CD4(+) cell count of 200-499 cells/microL (RR, 2.5) or < 200 cells/microL (RR, 3.7; referent, CD4(+) cell count of > or = 500 cells/microL); and alcoholism (RR, 2.0). Factors associated with a decreased risk included prescription of antiretroviral therapy (RR for monotherapy, 0.6; for dual therapy, 0.7; for triple therapy, 0.5) and pneumococcal vaccination (RR for persons vaccinated at a CD4(+) cell count of > or = 500 cells/microL, 0.5). We recommend that pneumococcal vaccine be given to HIV-infected persons before profound immunosuppression has occurred.

Pneumococcal and influenza immunization and human immunodeficiency virus load in children

OBJECTIVE

HIV-infected children receiving influenza vaccine, pneumococcal vaccine and both vaccines concurrently were studied to examine the effect of immunization on plasma HIV viral load.

METHODS

Thirteen children received immunizations: pneumococcal vaccine, 5; pneumococcal and influenza vaccines, 7; and influenza vaccine, 1. Most patients (12 of 13) were receiving combination reverse transcriptase inhibitor antiretroviral therapy without protease inhibitors at the time of immunization. Baseline plasma HIV RNA was determined 1 month prior (11 of 13), 2 weeks prior (12 of 13) and on the day of immunization (12 of 13). Plasma HIV RNA was assayed at 2 weeks (11 of 13), 4 weeks (12 of 13) and 3 months (5 of 13) after immunization. T cell activation markers (HLA-DR+, CD38+ and CD45RO+, CD28+) were examined for both CD4+ and CD8+ lymphocytes on the day of immunization and 2 weeks after immunization for 11 children.

RESULTS

Only one child developed a >0.5-log increase in viral load at any time after immunization. There was no correlation between an increase in viral load and antibody response to pneumococcal vaccine. At least one activation marker increased (> 10%) for two children receiving pneumococcal vaccine and two children receiving pneumococcal and influenza vaccines. One of these children experienced an increase in viral load.

CONCLUSION

Immunization with pneumococcal and influenza vaccines, alone or in combination, is rarely associated with a significant increase in HIV plasma RNA in children receiving combination antiretroviral therapy.

Effects of influenza vaccination in HIV-infected adults: a double-blind, placebo-controlled trial

Annual influenza vaccine is recommended for persons with HIV infection. Recent reports indicate that immunizations may increase HIV replication in infected individuals. Forty-seven HIV-infected patients were randomized to influenza vaccine or saline placebo using a double blind study design. One month after vaccination, plasma HIV-1 RNA increased in the vaccinated but not placebo group (p = 0.029). At 3 months, CD4% dropped an average of 1.6 points in the vaccinated group compared to an increase of 0.1 points in the placebo group (p = 0.039). Patients on stable antiretroviral regimens had CD4% drop an average of 2.3 points in the vaccinated group at 3 months versus 0.1 points in the placebo group (p = 0.015). It is concluded that HIV-infected patients are at risk for increased HIV replication and decreases in CD4% following influenza vaccination. Since influenza has not been associated with significant morbidity in this population, further study of routine influenza vaccination for HIV-infected patients is warranted.

Induction of specific T-cell responses in HIV infection

OBJECTIVES

To induce recovery of HIV-1-specific immune responses by combining immunization with antiviral chemotherapy.

DESIGN

Forty HIV-infected patients entered a double-blind study with recombinant gp160 in combination with zidovudine or placebo. The pretreatment observation period was around 2 years and the treatment period 5 years. Eighty matched HIV-infected patients served as controls.

METHODS

Immune status was monitored by proliferation assays with HIV-specific antigens, mitogens and recall antigens. Viral load, CD4 cell counts, apoptosis, T-cell clonal analysis and CC-chemokine receptor (CCR)-5 status were determined.

RESULTS

All immunized patients showed a strong and HIV-specific T-cell proliferative response. This response was related to the immunizations, and was not enhanced by the zidovudine monochemotherapy given during the first 6 months of the immunizations. The treatments did not significantly alter viral load. Potent antiviral combination therapy given to non-immunized individuals reduced their viral load but did not influence HIV-specific immune responses. There was a trend for an increased frequency of non-progression in the immunized group compared with controls. These individuals had both wild-type and mutant CCR-5 genes.

CONCLUSION

The results clearly show that restoration of HIV-specific T-cell immunity occurs after immunization with the HIV gp160 antigen and is not influenced by the addition of antiviral monochemotherapy. Even intensive chemotherapy alone did not restore HIV-specific immunity and immunization alone did not influence viral load. This suggests that combinations of intensive chemotherapy with specific HIV immunization would result both in viral load reduction and improved immune responses to HIV.

Pneumococcal vaccination of HIV-infected individuals: safety and efficacy

The finding of an increased risk of HIV-infected individuals for contracting pneumococcal diseases has led to the recommendation of antipneumococcal vaccination of HIV-infected individuals. However, due to reports of increased viral replication following immune stimulation, the vaccination policy has been called into question. The literature on changes in viral load and CD4 T cells following vaccination and the studies on the clinical efficacy of antipneumococcal vaccination is evaluated. It is concluded that the prevailing data do not lend support to the concern of a lasting effect of vaccination on viral load. Data on the clinical efficacy and serological responses of vaccination are too scanty to support the recommendation of antipneumococcal vaccination to HIV-infected individuals. In addition to the issue of clinical efficacy; many question remain to be addressed; for example, the protective antibody level, optimal timing and vaccination regimen are yet to be determined.