Early appearance of neutralizing antibodies after vaccination with an inactivated hepatitis A vaccine

Vaccination Guidelines for Patients With Immune-Mediated Disorders on Immunosuppressive Therapies

BACKGROUND:

Patients with immune-mediated diseases on immunosuppressive therapies have more infectious episodes than healthy individuals, yet vaccination practices by physicians for this patient population remain suboptimal.

OBJECTIVES:

To evaluate the safety and efficacy of vaccines in individuals exposed to immunosuppressive therapies and provide evidence-based clinical practice recommendations.

METHODS:

A literature search for vaccination safety and efficacy in patients on immunosuppressive therapies (2009-2017) was conducted. Results were assessed using the Grading of Recommendation, Assessment, Development, and Evaluation system.

RESULTS:

Several immunosuppressive therapies attenuate vaccine response. Thus, vaccines should be administered before treatment whenever feasible. Inactivated vaccines can be administered without treatment discontinuation. Similarly, evidence suggests that the live zoster vaccine is safe and effective while on select immunosuppressive therapy, although use of the subunit vaccine is preferred. Caution regarding other live vaccines is warranted. Drug pharmacokinetics, duration of vaccine-induced viremia, and immune response kinetics should be considered to determine appropriate timing of vaccination and treatment (re)initiation. Infants exposed to immunosuppressive therapies through breastmilk can usually be immunized according to local guidelines. Intrauterine exposure to immunosuppressive agents is not a contraindication for inactivated vaccines. Live attenuated vaccines scheduled for infants and children ⩾12 months of age, including measles, mumps, rubella, and varicella, can be safely administered as sufficient time has elapsed for drug clearance.

CONCLUSIONS:

Immunosuppressive agents may attenuate vaccine responses, but protective benefit is generally maintained. While these recommendations are evidence based, they do not replace clinical judgment, and decisions regarding vaccination must carefully assess the risks, benefits, and circumstances of individual patients.

Attachment of class B CpG ODN onto DOTAP/DC-chol liposome in nasal vaccine formulations augments antigen-specific immune responses in mice

Background

To overcome infectious diseases, the development of mucosal vaccines would be an effective strategy, since mucosal surfaces are the entry site for most pathogens. In general, protein antigens show inherently poor immunogenicity when administered by the mucosal route. Therefore, co-administration of an appropriate mucosal adjuvant is required to exert immune responses toward pathogen-derived antigens effectively. However, the development of a safe and effective mucosal adjuvant system is still challenging. Although, recent studies reported that oligodeoxynucleotides (ODNs) containing immunostimulatory CpG motifs (CpG ODNs) act as potent mucosal adjuvants and are useful in the formulation of nasal vaccines, there are some disadvantages. For instance, the administration of phosphorothioate (PS)-modified CpG ODNs can induce adverse systemic effects, such as splenomegaly, in a dose-dependent manner. Therefore, a reduced dose of CpG ODN might be crucial when used as vaccine adjuvant for clinical purposes. Therefore, we prepared a CpG ODN-loaded cationic liposome, and evaluated its mucosal adjuvant activity.

Results

We prepared a CpG ODN-loaded DOTAP/DC-chol liposome that was stable during our experiments, by mixing CpG ODNs and liposomes at an N/P ratio of 4. Further, we demonstrated that the attachment of class B CpG ODN to the DOTAP/DC-chol liposomes synergistically enhanced antigen-specific IgA production in the nasal area than that induced by CpG ODN and DOTAP/DC-chol liposomes alone. The endpoint titers were more than tenfolds higher than that induced by either single CpG ODN or single DOTAP/DC-chol liposomes. Additionally, although serum IgG1 responses (indicated as a Th2 response) remained unchanged for DOTAP/DC-chol liposomes and CpG ODN-loaded DOTAP/DC-chol liposomes, the CpG ODN-loaded DOTAP/DC-chol liposomes synergistically induced the production of serum IgG2a (indicated as a Th1 response) than that by the individual liposomes.

Conclusions

We conclude that the advantage of using DOTAP/DC-chol liposome harboring CpG ODN is it induces both antigen-specific mucosal IgA responses and balanced Th1/Th2 responses. Therefore, such a combination enables us to resolve the adverse effects of using CpG ODNs (as a mucosal adjuvant) by reducing the overall dose of CpG ODNs. Further, the biodegradable and essentially non-antigenic nature of the liposomes makes it superior than the other existing mucosal adjuvants.

A Hematological Menace: Multiple Venous Thrombosis Complicated by Acquired Factor VIII Deficiency

Patient: Male, 21

Final Diagnosis: Acquired Factor VIII Deficiency

Symptoms: Abdominal hematoma • DVT • life threatening bleeding

Medication: —

Clinical Procedure: Life saving medical therapy

Specialty: Hematology

Host responses from innate to adaptive immunity after vaccination: molecular and cellular events

The availability of effective vaccines has had the most profound positive effect on improving the quality of public health by preventing infectious diseases. Despite many successful vaccines, there are still old and new emerging pathogens against which there is no vaccine available. A better understanding of how vaccines work for providing protection will help to improve current vaccines as well as to develop effective vaccines against pathogens for which we do not have a proper means to control. Recent studies have focused on innate immunity as the first line of host defense and its role in inducing adaptive immunity; such studies have been an intense area of research, which will reveal the immunological mechanisms how vaccines work for protection. Toll-like receptors (TLRs), a family of receptors for pathogen-associated molecular patterns on cells of the innate immune system, play a critical role in detecting and responding to microbial infections. Importantly, the innate immune system modulates the quantity and quality of longterm T and B cell memory and protective immune responses to pathogens. Limited studies suggest that vaccines which mimic natural infection and/or the structure of pathogens seem to be effective in inducing long-term protective immunity. A better understanding of the similarities and differences of the molecular and cellular events in host responses to vaccination and pathogen infection would enable the rationale for design of novel preventive measures against many challenging pathogens.

Immunogenicity, safety, and interchangeability of two inactivated hepatitis A vaccines in Chilean children

OBJECTIVES

To compare the immunogenicity, safety, and interchangeability of two pediatric hepatitis A vaccines, Avaxim 80U-Pediatric and Havrix 720, in Chilean children.

METHODS

In this randomized trial, 332 hepatitis A virus (HAV) seronegative children from 1 to 15 years of age received two doses of Avaxim, two doses of Havrix, or Havrix followed by Avaxim, 6 months apart. Anti-HAV antibody titers were measured before and 14 days after the first dose of vaccine, and before and 28 days after the second dose of vaccine. Immediate reactions were monitored; reactogenicity was evaluated from parental reports.

RESULTS

Seroconversion rates after the first vaccination were 99.4% and 100% for Avaxim and Havrix, respectively. Anti-HAV geometric mean concentrations (GMCs) were 138 mIU/ml for Havrix (95% confidence interval (CI): 120; 159) and 311 mIU/ml for Avaxim (95% CI: 274; 353). GMCs increased to 4008 mIU/ml after two doses of Havrix, 8537 mIU/ml following two doses of Avaxim, and 7144 mIU/ml in children who received Havrix with Avaxim as the second dose. Following the first injection, 36% of subjects given Avaxim and 44% given Havrix reported local reactions; 38% of subjects in the Avaxim group and 40% in the Havrix group reported systemic reactions related to vaccination. Solicited reactions were less frequent after the second dose of Avaxim or Havrix, occurring in 27% to 37% of subjects.

CONCLUSIONS

No significant difference in seroconversion rates was seen 14 days after a single dose of vaccine. A two-dose schedule with either vaccine or with Havrix/Avaxim provided a strong booster response. Both vaccines were well tolerated and can be recommended for routine vaccination of Chilean children. Avaxim 80 may be used to complete a vaccine schedule begun with Havrix 720.

Genetic analysis of HAV strains in Tunisia reveals two new antigenic variants

To evaluate the genetic variability of hepatitis A virus (HAV) isolates in Tunisia, serum samples were collected from 99 patients in different Tunisian areas in 2003 containing 92 cases with acute hepatitis, five with severe acute hepatitis and two with fulminant hepatitis. The entire VP1 gene was amplified and sequenced. Sequences were then aligned and a phylogenetic analysis was performed. Additionally, the amino acid (aa) sequence of the VP1 was determined. The analysis of Tunisian HAV isolates revealed that all the isolates were sub-genotype IA with 96.4%-99.8% of identity and showed the emergence of two novel antigenic variants. The Tun31-03 antigenic variant, with a 38 aa deletion containing Met156, Val171, Leu174 and Ala176 and located between 150 and 187 aa of the VP1 protein where neutralization escape mutations, was found. The second antigenic variant, Tun36-03, was isolated from a patient with fulminant hepatitis and presented a substitution of Thr by Pro at position 10 of the VP1 protein. This amino acid is located in a peptide presenting an antigenically reactive epitope of the VP1 protein. This substitution has never been described previously.

Genetic relatedness of Cuban HAV wild-type isolates

Knowledge of the nucleotide sequence in the region of the putative VP1/2A junction of the Hepatitis A virus (HAV) genome has enabled differentiation of HAV strains and their classification into seven genotypes, in some of which sub-genotypes A and B can be defined. A 168 base segment encompassing the putative VP1/2A junction of 27 clinical wild-type isolates of HAV from Cuba was amplified by reverse transcriptase-polymerase chain reaction and then sequenced. The Cuban isolates are clustered within sub-genotype IA. A single amino acid substitution, which does not correspond with any of the reported changes for other strains, was observed. A new sub-genotype variant is therefore postulated. This study provides new data on the genetic relatedness of HAVs from Cuba and on the distribution of sub-genotype IA in the Caribbean area.

Comparative immunogenicity and tolerance of Vaqta and Havrix

In an open-label, randomised trial, 520 adults of both sexes aged 18-30 years were allocated to receive one of two inactivated hepatitis A vaccines; Vaqta or Havrix, at 0 and 24 weeks. Doses used were 50 or 100 antigen units (U) of Vaqta and 1440 enzyme linked immunosorbent assay U of Havrix given as 1 ml intramuscular injections. For each trial group safety data were available for all subjects and full serological data for more than 80% of randomised volunteers. Local side effects which were mild in most cases were significantly (p < 0.0001) more common with Havrix than with Vaqta, irrespective of dose given. Systemic tolerance was similar for the 3 regimens. From 4 weeks after the first dose, > or =94% of the subjects had seroconverted. The mean antibody titres 4 weeks after the second vaccine dose were 2978, 4346 and 1589 mIU/ml in subjects who were randomised to Vaqta 50 U/dose, Vaqta 100 U/dose and Havrix 1440 U/dose, respectively. The 2 vaccines had similar immunogenicity but local tolerance was better with Vaqta.