Efficacy of hepatitis B immunization with reduced intradermal doses

Needleless vaccine delivery using micro-shock waves

Shock waves are one of the most efficient mechanisms of energy dissipation observed in nature. In this study, utilizing the instantaneous mechanical impulse generated behind a micro-shock wave during a controlled explosion, a novel nonintrusive needleless vaccine delivery system has been developed. It is well-known that antigens in the epidermis are efficiently presented by resident Langerhans cells, eliciting the requisite immune response, making them a good target for vaccine delivery. Unfortunately, needle-free devices for epidermal delivery have inherent problems from the perspective of the safety and comfort of the patient. The penetration depth of less than 100 μm in the skin can elicit higher immune response without any pain. Here we show the efficient utilization of our needleless device (that uses micro-shock waves) for vaccination. The production of liquid jet was confirmed by high-speed microscopy, and the penetration in acrylamide gel and mouse skin was observed by confocal microscopy. Salmonella enterica serovar Typhimurium vaccine strain pmrG-HM-D (DV-STM-07) was delivered using our device in the murine salmonellosis model, and the effectiveness of the delivery system for vaccination was compared with other routes of vaccination. Vaccination using our device elicits better protection and an IgG response even at a lower vaccine dose (10-fold less) compared to other routes of vaccination. We anticipate that our novel method can be utilized for effective, cheap, and safe vaccination in the near future.

Evaluation of SIV-lipopeptide immunizations administered by the intradermal route in their ability to induce antigen specific T-cell responses in rhesus macaques

Numerous clinical and experimental observations have shown that cellular immunity, in particular CD8+ T-lymphocytes, plays an important role in the control of HIV infection. We have focused on a lipopeptide vaccination strategy that has been shown to induce polyepitopic T-cell responses in both animals and humans, in order to deliver simian immunodeficiency virus (SIV) antigens to rhesus macaques. Given the relevance of antigen administration route in the development of an effective cellular immune response, this study was designed to assess SIV lipopeptide immunizations administered either by the intradermal (ID) or the intramuscular (IM) routes in their ability to elicit GAG and NEF multispecific T-lymphocytes in the rhesus macaque. Antigen specific T-cell responses were observed between 7 and 11 weeks following vaccination in both groups. Macaques immunized by the IM route yielded antigen-specific IFN-gamma secreting lymphocytes in response to no more than two pools of peptides derived from SIV-NEF. In contrast, among the four ID-immunized macaques, two presented multi-specific T-cell responses to as many as four pools of SIV-NEF and/or GAG peptides. Responses persisted 16 weeks following the vaccination protocol in one of the ID-vaccinated macaques. The induction of such responses is of great clinical relevance in the development of an effective HIV vaccine. Given the crucial role of CD8+ T-lymphocytes in HIV/SIV containment, vaccination through the intradermal route should merit high consideration in the development of an AIDS vaccine.

Booster doses of hepatitis B vaccine: responses to low-dose inoculations

OBJECTIVE

To examine the anamnestic response to hepatitis B vaccine in previously vaccinated subjects.

DESIGN

Subjects who had received a course of hepatitis B vaccine at least two years previously had a sample of blood taken before and seven days after a low-dose booster of hepatitis B vaccine.

SETTING AND PARTICIPANTS

A pilot group of laboratory scientists in the Microbiological Diagnostic Unit; fifth year medical students, University of Melbourne; and a group of ambulance officers from the Geelong Ambulance Depot (Victoria). All participants volunteered after having been informed of the study.

OUTCOME MEASURES

Serum levels of antibody to hepatitis B surface antigen (HBsAg) were measured before and after the booster dose of vaccine and, when available, in serum taken a month after the end of the primary course of vaccine, and the changes in antibody level were studied.

RESULTS

Although some individuals with a restricted antibody response were identified, most showed a quick response. There was limited evidence that this rise peaked early and began to fall within weeks.

CONCLUSIONS

In many subjects, levels of antibody to HBsAg peak early after booster doses of vaccine but the rapid anamnestic response to small amounts of antigen make it probable that effective protection from symptomatic illness may be long lasting, when there has been a satisfactory primary response. This provides an argument for testing for adequate seroconversion after vaccination.

Persistence of antibody to hepatitis B surface antigen after low-dose, intradermal hepatitis B immunization and response to a booster dose

To determine the duration of antibody after low-dose, intradermal (i.d.), plasma-derived hepatitis B vaccination and the response to a booster dose, we studied two classes of medical students who were immunized with 2 micrograms doses i.d. In one class, 73/88 (85%) who had been immunized by skilled personnel at 0, 1 and 6 months, had protective concentrations (greater than or equal to 10 mIU ml-1) of anti-HBs at 20 months after the first dose. Twelve (92%) out of 13 students who received only two doses at 0 and 1 months also had protective concentrations at month 20. At month 27, 11/16 (69%) with antibody less than or equal to 10 mIU ml-1 responded to a fourth dose of 2 micrograms i.d. with protective concentrations of anti-HBs. In the second class, after three doses of vaccine at 0, 1, and 6 months, protective concentrations of anti-HBs were present in 90/93 (97%) at 14 months and in 71/80 (89%) at 25 months. In those who received only two doses, protective concentrations were found in 24/31 (74%) at 14 months and 9/16 (56%) at 25 months. After a booster dose of 2 micrograms i.d. at month 25, anti-HBs concentrations rose from a geometric mean of 78 to 1198 mIU ml-1 in 60 subjects previously immunized with three doses and from 18 to 1054 mIU ml-1 in 16 students previously immunized with only two doses. Overall, 73/76 (96%) of students in the second group had protective concentrations of antibody after the booster dose.(ABSTRACT TRUNCATED AT 250 WORDS)

Long term observation of the effect of intradermal hepatitis B vaccination on mentally retarded patients

Sixty-two patients of two institutions for mentally retarded patients were immunized intradermally with 4 micrograms doses of plasma-derived hepatitis B vaccine made in Japan, initially at month 0.1 and 6. The three vaccinations induced antibodies in 93.5% (90.9% in those with Down's syndrome (DS), 94.1% in other forms of mental retardation (OMR) of the vaccinees within 9 months after the first injection, and the percentage of geometric mean titers of antibody above 10 mIU/ml was 89.3% (81.8% DS, 84.3% OMR) within 9 months. Within 2 years, the seroconversion rate showed a significantly higher decrease in subjects with DS (54.5%) than in OMR (86.3%), and the percentage of vaccines with above 10 mIU/ml also showed a significantly higher decrease in subjects with DS (36.4%) than in those with OMR (74.5%) (p less than 0.05). In the OMR patients, the antibody response persisted for 2 years, decreased remarkably in the DS patients.

Intradermal hepatitis B vaccination

The availability of vaccine since 1982 for immunization against hepatitis B virus (HBV) has had minimal impact on the disease; mass immunization has been suggested. Intradermal vaccination, which has precedent in prophylaxis of other infectious diseases, has been investigated as a low-cost alternative to traditional intramuscular HBV vaccination. Results of open and comparative trials indicate similar seroconversion rates for intradermal and intramuscular HBV vaccination routes in healthy adults. However, antibody titers and, presumably, duration of antibody protection appear to be decreased with intradermal HBV vaccination. Limited data suggest that demographic factors such as age and gender may affect vaccine responsiveness to intradermal HBV vaccine. Adverse skin reactions are common but do not represent a deterrent to continued intradermal HBV vaccination. There is a need for large-scale prospective comparative trials to substantiate the value of intradermal HBV vaccination. Nevertheless, the potential economic and epidemiologic benefit of intradermal vaccination justifies continued investigation for prevention of HBV infection.

Effectiveness of intradermal hepatitis B immunization of hospital staff

Three doses of hepatitis B vaccine were administered via an intradermal route to 316 health service staff. One month after the final dose, 89.9% of subjects had antibodies to hepatitis B surface antigen at levels of 10 IU/l or greater. A programme of hepatitis B immunization based upon the intradermal route is substantially less expensive than one using an intramuscular technique, and can enable health authorities to provide protection for increased numbers of staff without diverting resources from other programmes of health care.

Intradermal hepatitis B immunization with yeast-derived vaccine: serological response by sex and age

The efficacy and acceptability of yeast-derived recombinant hepatitis B vaccine given by the intradermal route was investigated in 221 health care volunteers. Two hundred and sixteen received a full course of three doses of vaccine. Only one subject was withdrawn because of a significant adverse reaction (psoriasis). The vaccine stimulated an antibody response in 81%. The response to the vaccine was better in women than in men (87% compared with 71%, p = 0.007) and in women below the age of 40 years compared with older women (94% compared with 76%, p = 0.01). For men the response showed a sequential decline with age for each decade (90% responders from age 29 or less, 72% aged 30-39 and 65% aged 40 or more, p = 0.04). Retrospective enquiry showed that over 90% had found the intradermal route acceptable and 59% would prefer vaccine by the intradermal route in preference to intramuscular notwithstanding local reactions. Although the seroconversion rate was of a high order in younger women the antibody titres were not high with only 9 of 215 recipients developing titres greater than 1000 mIU/ml, a level which could be expected to ensure prolonged immunity. A fourth intradermal dose of vaccine given to 60 volunteers who had shown a low response (less than 38 mIU/ml) or no serological response to a three-dose course stimulated a good booster effect (to 150-600 mIU/ml) in only 5 (8%).

Intradermal hepatitis B vaccination for mentally retarded patients

We investigated immune responses in 63 mentally retarded patients each given a low-dose (4 micrograms) intradermally of plasma-derived hepatitis B vaccine made in Japan and which was repeated after 1 and 6 months. Two doses of the vaccine induced antibodies in 85.5% these patients. A further dose 6 months later induced antibodies in 93.5% of the recipients and markedly increased the proportion of recipients with acceptable or high concentrations of antibody. The numbers of acceptable and high responders decreased slightly during a period of 12 months. The rate of acquiring antibody was significantly higher in the males. No significant differences in antibody response with regard to age and type of disease were observed. One patient with Down's syndrome, who acquired a low concentration of antibody after vaccination, was infected with hepatitis B virus. Supplementary vaccination may be necessary for poor responders in order to obtain protection. Side-effects resulting from the vaccination were not severe in any patients. These results suggest that low-dose, intradermal hepatitis B vaccination is safe and effective.