Persistence of rabies antibody 5 years after pre-exposure prophylaxis with human diploid cell antirabies vaccine and antibody response to a single booster dose

Rabies Antibody Response After Booster Immunization: A Systematic Review and Meta-analysis

Although fatal once symptomatic, rabies is preventable by administration of pre- and post-exposure vaccines. International guidelines suggest lifelong protection by a pre-exposure vaccination scheme followed by timely post-exposure vaccines. Rapidity and magnitude of the antibody recall response after booster inoculation are essential, as many people have been previously immunized a long time ago. The objective of this study was therefore to systematically review the evidence on the boostability of rabies immunization to date. We included 36 studies, of which 19 studies were suitable for meta-analysis. Reduced antibody levels were found after intradermal primary schedules as compared to intramuscular schedules. However, responses after booster immunization were adequate for both routes. Although studies showed that antibody levels decline over time, adequate booster responses were still retained over long time intervals indicating that post-exposure treatment is effective without extra measures after long periods of time.

Immunogenicity and booster efficacy of pre-exposure rabies vaccination

A multivariate analysis was used to identify factors influencing the immunogenicity of rabies vaccine and to assess the efficacy of booster injections in a cohort of 407 people monitored prospectively for 10 years after primary vaccination. Rabies vaccine (HDCV or PVRV) was injected by intramuscular route either on days 0 and 28 or on days 0, 7 and 28. All the participants received a booster injection on day 365. At the end of follow-up (year 10), 163 subjects had titers >0.5IU/ml (group A) and 59 subjects had titers <0.5IU/ml (group B: poor responders). The number of injections had a significant influence (P<0.001) on the magnitude of the serological response to rabies vaccine, but the type of vaccine and the potency of the batches did not (P=0.07 and P=0.06, respectively). The difference between GMTs on day 365 and day 379 was significantly lower in group B than in group A (13 and 50.70IU/ml, respectively; P<0.001). In conclusion, our study confirms that the rabies pre-exposure vaccination protocol of three intramuscular injections significantly decreases the proportion of poor responders at 10 years. Moreover, our findings indicate that a routine booster injection at 1 year could significantly increase the levels and duration of antibody titers.

Identification of a novel methicillin-resistant Staphylococcus aureus epidemic clone in Córdoba, Argentina, involved in nosocomial infections

Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are increasingly a main health concern worldwide for hospitalized patients. In addition, the prevalence of community-acquired infection has risen continuously during the last few years. Some MRSA clones spread easier than others within the hospital environment and therefore are frequently implicated in outbreaks. Thus, the spread of a unique epidemic multiresistant clone, the so-called South American clone, is the main cause of nosocomial infections produced by this bacterium in Brazil and in some regions of Argentina, Chile, and Uruguay. In the present work we describe the identification of a novel clone of MRSA that is involved in nosocomial infections and that shows a prevalence as high as that for the South American clone. A total of 53 consecutive single-patient MRSA isolates were recovered during a 3-month period (May to July 1999) from six different hospitals (955 beds) in Córdoba. The isolates were initially typed according the antibiotic resistance and phage susceptibility patterns, followed by genotyping using pulsed-field gel electrophoresis (PFGE). PFGE analysis of the 53 MRSA isolates revealed six major types (A to F) and 25 subtypes. The B-type DNA pattern was indistinguishable from that of the South American epidemic clone observed in 34% of the isolates. A novel highly prevalent clone, showing the A-type DNA pattern and representing 38% of the isolates, was also identified. Moreover, the most frequent subtype of the A clonal family triggered an outbreak in a hospital 2 months later, further confirming its epidemic feature.

Three-year experience with 4-site intradermal booster vaccination with rabies vaccine for postexposure prophylaxis

For booster vaccination of previously immunized persons with potential exposure to rabies, the World Health Organization recommends 2 doses of cell-culture vaccine administered intramuscularly or intradermally on days 0 and 3. We believe that four 0.1-mL intradermal booster doses given on a single day could be used at no risk to the recipient. We studied use of a single booster vaccination on day 0 followed by four 0.1-mL intradermal doses of cell-culture rabies vaccines, and we determined that this is a safe, convenient, and economical regimen for postexposure treatment of previously vaccinated individuals.

Persistence of humoral immunity to rabies 1100 days after immunization and effect of a single booster dose of rabies vaccine

Forty-four vaccinees immunized with rabies vaccine and human rabies immunoglobulin according to the abbreviated intramuscular regimen (the 2-1-1 schedule) were followed-up after 1100 days and had their blood samples taken. The persistence of rabies neutralizing antibody was proven in the sera of all vaccinees. 56% of whom demonstrated titres > or = 0.5 IU ml-1. At the same day the vaccinees were given a single booster dose of vaccine whose effect was measured 2 weeks later. With the RFFI test on day 1114, sera revealed an extraordinarily high booster response in all 44 vaccinees. The study proved the anamnestic response after a full course of rabies vaccination to be a very stable one, and the capability of a single booster dose of vaccine to evoke high-titred rabies antibody response. Of the four vaccines used in the study, under comparable conditions HDCV proved superior to PCECV PDEV and PVRV on all 3 days of serology-35, 1100 and 1114, though this difference was statistically attested only on days 35 and 1114.

Effect of one booster dose in antirabies vaccination

The antibody response obtained after one booster dose of rabies vaccine prepared in suckling mice brains at Serviço de Saúde Pública da Cidade do Rio de Janeiro is described. Four prime vaccinal groups were used: group I, persons who had received 16 doses 10 years before this investigation; group II, persons who had received 5 doses of the vaccine 10 years before; group III, persons who had received 9 doses 5 years before; and group IV, persons who had received 16 doses 5 years before. One booster dose of the vaccine was administered to all persons involved in the study. Blood samples were collected before vaccination (day 0), then 7 and 30 days after vaccination. Antibody titres were determined by seroneutralization test in mice (SWM). The results demonstrated that all persons who had been treated with 5, 9 or 16 doses of the vaccine 5 to 10 years before had their antibody titres increased on the 7th and 30th days after one booster dose.