Ml Of Vaccine Research Articles

Safety and efficacy of an inactivated vaccine against Lactococcus garvieae in rainbow trout ( Oncorhynchus mykiss)

We studied the safety and efficacy of an inactivated vaccine (Ichtiovac-Lg) against Lactococcus garvieae in rainbow trout ( Oncorhynchus mykiss). In an initial dose-response experiment to test safety, we injected 50 rainbow trout weighing 30–40 g with a double dose of vaccine (0.2 ml) intraperitoneally. We observed these fish three times a day until day 50 post-vaccination when they were killed to evaluate visceral reactions, adhesions and intraperitoneal absorption. Survival was 100% in both the treatment and control groups and no significant differences were found in percentage of severe adhesions and pigmentation of peritonea and viscera. In a second trial, we injected 50 rainbow trout weighing 30–40 g with 0.1 ml of vaccine and a control group was injected with 0.1 ml of PBS intraperitoneally. On day 29 post-vaccination, both groups were challenged by intraperitoneal injection with 0.1 ml of a virulent heterologous strain of L. garvieae at 3 × 10 6 cfu ml −1 and fish were observed for a further 21 days. At the end of the experiment, the survivals of the vaccinated fish and control group were 94 and 4%, respectively.

Complications de la revaccination par le BCG : 12 observations

Calmette-Guérin bacillus (BCG) is a live attenuated strain used in tuberculosis vaccination. Local and systemic side-effects, although rare, are associated with BCG vaccine. They are common in cases of overdose and with poor vaccination techniques. These complications also occur in some cases of revaccination. This was a retrospective study over a period of 5 years between January 2000 and March 2005. 12 patients presenting complications following revaccination with BCG were observed. Patients were revaccinated with BCG following a negative intradermal reaction test. The following parameters were recorded: age, gender, history, vaccination method, type of complication, treatment and outcome. There were 10 men and 2 and women of mean age 21 years (19 to 23 years). Mean time to consultation was 4 weeks. Complications comprised subcutaneous abscess in 8 cases, deep chronic ulcers in 4 cases complicated by humeral osteitis in one case. The dose administered was 0.1 ml in 9 patients and 1 ml in 3 others (i.e. 10 times the recommended dose). Six patients had extensive and progressive ulceration, with one positive culture, the presence of a granuloma with caseum necrosis and one case of humeral osteitis, and specific treatment was given. Revaccination is no longer recommended by the WHO since efficacy is considered to be low or even nil. Intradermal injection is the reference method for BCG vaccination. Technical errors such as injection of an excessively high dose of the vaccine or subcutaneous administration of the vaccine solution increase the incidence of adverse effects. In our study, three patients erroneously received 1 ml of vaccine and the injection was too deep in 9 cases. There are few reports in the literature concerning the underlying mechanisms of these post-revaccination accidents; two major physiopathological mechanisms, infectious and immunological, are discussed. There is no consensus regarding treatment of these complications. Six of the 12 patients received specific therapy for 6 months.

A bivalent vaccine against goat pox and Peste des Petits ruminants induces protective immune response in goats

Safety and immunogenicity of an experimental combined vaccine comprising attenuated strains of Peste des Petits ruminants virus (PPRV) and goat poxvirus (GTPV) was evaluated in goats. Goats immunized subcutaneously with 1 ml of vaccine consisting of 10 3 TCID 50 of each of PPRV and GTPV were monitored for clinical and serological responses for a period of 4 weeks postimmunization (pi) and postchallenge (pc). Specific antibodies directed to both GTPV and PPRV could be demonstrated by indirect ELISA and competitive ELISA, respectively following immunization. All the immunized animals resisted challenge with virulent strains of either GTPV or PPRV on day 28 pi, while control animals developed characteristic signs of disease. Specific antigen could be detected in the unvaccinated control animals after challenge but not from any of the immunized goats. Bivalent vaccine was found to be safe and induced protective immune response in goats as evident from sero conversion as well as challenge studies, indicating that component vaccines did not interfere with the immunogenicity of each other.

Determination of antibody response against inactivated agalactia vaccine in small ruminants

An inactivated agalactia vaccine was prepared with Mycoplasma agalactiae in fermenter. The culture was inactivated and subsequently adjuvanted with aluminum hydroxide gel. Four sheep and four goats were immunized with the experimental vaccine. Two doses of 1ml of vaccine were administered three weeks interval. Monthly, blood samples were taken from the vaccinated animals up to the fifth month along with hyperimmune and negative controls. Elisa was set up and sera were assayed against Lorestan live antigen. Results indicated that antibodies were determined in vaccinated sheep and goats with the maximum overall mean titres of 1.25 and 1.028, at one month post-vaccination and minimum mean titres of 0.674 and 0.538 respectively.

Simulated post-exposure rabies vaccination with purified chick embryo cell vaccine using a modified Thai Red Cross regimen

Objectives: Currently, two intradermal regimens for the administration of cell culture rabies vaccines are approved by the WHO for rabies post-exposure prophylaxis: the two site Thai Red Cross regimen (TRC) and the eight site regimen. For the TRC regimen the volume of vaccine recommended per dose is 0.1 ml of purified Vero cell rabies vaccine (PVRV) and 0.2 ml of purified chick embryo cell vaccine (PCEC). The objective of the present study was to evaluate comparatively the immune response to PCEC and PVRV vaccines administered by the TRC regimen using a uniform dose of 0.1 ml of vaccine. Methods: Forty-two subjects received TRC regimen (2-2-2-0-1-1) with 0.1 ml of PCEC vaccine and 38 subjects received the same regimen with PVRV. The rabies neutralizing antibody response in these subjects on days 10, 28, 90 and 180 was determined by the standard mouse neutralization test (MNT). Results: There was adequate antibody response with both the vaccines and 100% seroconversion was observed by day 10. Furthermore, the antibody titers obtained with PCEC did not differ significantly from those obtained with PVRV on all days tested ( p>0.05). Conclusions: It can be concluded from the results that an adequate antibody response can be obtained with PCEC vaccine when administered by the TRC regimen even after reducing the quantity of vaccine from 0.2 ml to 0.1 ml per intradermal dose. The feasibility of using this regimen in true post-exposure cases needs to be further evaluated.

Economical multi-site intradermal regimen with purified chick embryo cell vaccine (Rabipur) prevents rabies in people bitten by confirmed rabid animals

Objective: To determine the efficacy of a cost-effective multi-site intradermal regimen with purified chick embryo cell vaccine (PCECV Rabipur) in preventing rabies in people bitten by confirmed rabid dogs. Methods: Thirty-two people of different age groups who were severely bitten by confirmed rabid dogs were immunized with PCECV using the WHO recommended multi-site intradermal regimen of 0.1 mL of vaccine at eight sites on day 0, at four sites on day 7, and at one site each on days 28 and 90. In addition, passive immunization with human or equine rabies immunoglobulin was administered to 22 of these people before administering vaccine. They were followed for up to 3 years with periodic estimation of neutralizing antibody levels in their serum by mouse neutralization test (MNT). Results: There was an excellent immune response with more than protective titers (>0.5 IU/mL) on all days tested up to the end of the 3-year observation period. More significantly, protective titers were seen in all subjects by day 7. Only minimal side effects were observed. All the patients were doing well at the end of the 3-year observation period, which is generally considered to be the maximum incubation period for rabies in humans. Conclusions: It can be concluded that this multi-site regimen with or without passive immunization has prevented the development of rabies encephalitis in these people bitten by confirmed rabid dogs. This should encourage more such studies, so that this cost-effective economical regimen with safe and potent cell culture vaccines can replace highly reactogenic neural tissue-derived Semple vaccine in developing countries such as India.

Evaluation of a single dose of half strength inactivated influenza vaccine in healthy adults

Because of delays in the manufacturing of the 2000–2001, trivalent inactivated influenza vaccine in the US, there were concerns that there might be shortages of vaccine supply in the US. Therefore, we conducted a prospective, randomized, open-label, multicenter trial at six academic medical centers in the US, to evaluate the immunogenicity of a half dose of inactivated vaccine in healthy adults. Healthy adults between the ages of 18 and 49 were randomized to receive either a full 0.5 ml (15.5 μg of each HA antigen) dose or a 0.25 ml (7.75 μg of each HA antigen) dose of the 2000–2001 trivalent inactivated influenza vaccine by intramuscular injection. Sera were obtained for assessment of hemagglutination-inhibiting antibody to each of the three strains contained in the vaccine before and 21 days after vaccination. The proportions of individuals achieving a post-vaccination titer of ≥1:40, the geometric mean titers (GMTs) of post-vaccination antibody, and the proportions of individuals with a four-fold or greater increase in antibody were lower for all three strains in those receiving 0.25 ml of vaccine compared to those receiving 0.5 ml. However, the differences were small for all three antigens. The upper 95% confidence limits for differences between 0.25 and 0.5 ml doses were less than 20% for rates of achieving a titer of ≥1:40 and four-fold response, and less than 1.5 for the ratios of GMTs between dose groups, for all three vaccine antigens. These results suggest that when vaccine is in short supply, a strategy using a half dose in healthy adults could increase the number of people vaccinated with relatively little adverse impact on vaccine immunogenicity.

Development of fowl cholera vaccine: I. Protection of Pasteurella multocida local isolate vaccine against challenge of homologous and heterologous strains.

Pasteurella multocida locally isolated from chicken and ducks (BCC 299, BCC 2331, DY1, DY2, 12TG, 15TG) andimported strains (BCC 1359, 1362; HEDDLESTON group 1 and 6 respectively) had been tested for its pathogenicity in theprevious study. The aims of this experiment were to study the preparation of local isolate pasteurellosis vaccines and to determine the protective effect of that vaccines in chicken against the highly pathogenic local isolates of P. multocida . Killed monovalent, bivalent and polyvalent pasteurellosis vaccines were prepared and each was adjunvanted with aluminum hydroxide gel at a final concentration of 1.5% and the cell concentration was equal to the No 10 of MacFarland tube standard. Each of the vaccine prepared was used to vaccinated on a group of six week old of layer chicken (8 per group). Each chicken was subcutaneously injected with 0.2 ml of vaccine, four weeks later each was boostered with similar vaccine with the same dose. Two weeks after giving the boostered vaccine each group of chicken were challenged, half with life bacterium of P. Multocida BCC 2331 and other with DY2. Any chick which survive after challenge was designated as protected by vaccination. Before vaccination 1 ml of blood was drawn from each of chicken and then two weeks apart up to challenge. Serum from each sample was separated and kept in deep freeze until tested by enzyme-linked immunosorbent assay (ELISA). Chicken vaccinated with killed whole cell P. multocida vaccines of monovalent (BCC 2331 or DY2) and bivalent (BCC 2331 + DY2) were protected against challenge with live bacterium of either BCC 2331 or DY2 at rate 67-100%. There was no protection in chicken vaccinated with either BCC 299, DY1, 12TG, 15TG, BCC 1359, or 1362 killed vaccine. Similarly no protection of chicken vaccinated with either DY1 + BCC299, 12TG + 15TG or BCC 1359 + BCC 1362 bivalent vaccines. The protection rate of the polyvalent local isolate vaccine was at average 50-75%. All vaccinated chicken showed the presence of antibody responses againsted the extract cell and whole cell antigens of either P. multocida BCC 2331 or DY2 local isolate as detected by ELISA. The antibody responses from vaccinated chicken against extra cellular antigens prepared from broth cultures of BCC 2331 and DY2 were detected only from vaccinated chicken with vaccine containing killed antigen of BCC 2331 and/or DY2 isolate. It is likely, the local isolate of P. multocida BCC 2331 and DY2 would be benefit for producing inactive fowl cholera vaccine use in Indonesia, but the protective antigen that enhances immune protection should be determined by means of immunoblotting techniques. Key words: Pasteurella multocida , fowl cholera, vaccine, protection

Study of the safety, immunogenicity and seroconversion of a hepatitis-B vaccine in malnourished children of India

Sixty rural children who were seronegative for HBV markers received three doses of 10 μg of a new Hepatitis-B vaccine, Revac-B (1 ml of vaccine contains 20 μg recombinant surface antigen) that was formulated from hepatitis-B surface antigen expressed in a recombinant strain of Saccharomyces cerevisiae. Vaccines were administered on a 0, 30 and 60-day schedule. Levels of anti-HBs titres were determined on the 30th, 60th and 90th days following the initial injection. None of the participants in the trial had serious adverse reactions and the frequencies of minor side effects were minimal. No clinically important adverse effects which could be considered as directly related to the vaccination were recorded. The volunteers showed a very good immune response and were seroprotected on the 30th day after the first dose of vaccination. The present study revealed that the new vaccine, Revac-B is highly immunogenic and is well tolerated.

Immunologic responses of domestic and bighorn sheep to a multivalent Pasteurella haemolytica vaccine.

The efficacy of a Pasteurella haemolytica vaccine (serotypes A1, A2, and T10) to induce humoral antibodies and alter colonization of the upper respiratory tract by related P. haemolytica spp. strains was evaluated in 10 bighorn (Ovis canadensis canadensis) and 10 domestic (Ovis aries) sheep. Sheep of each species were divided into five pairs based on age and history of respiratory disease. One sheep in each pair was vaccinated twice 2 wk apart with 2 ml of vaccine (VAC group) and the remaining animals (NV group) were injected with 2 ml of sterile saline. Mild, transient lameness was the only observed adverse effect. Blood sera from the sheep were tested for agglutinating antibodies against whole cells of A1, A2, and T10 and for leukotoxin neutralizing antibodies. Antibody titers were expressed as the reciprocal log2 of the highest reactive dilutions. Domestic sheep > 1-yr-old and two bighorn sheep with a history of A1 infection had higher titers throughout the study against A1 cells than domestic sheep < 1-yr-old and bighorns without a history of A1 infection. Both domestic and bighorn sheep had log2 titers of 8 to 12 against A2 cells and 6 to 12 against T10 cells during this time. Bighorn sheep in the VAC group had 2 to 32 fold titer increases for A1 cells by 2 wk post-vaccination (PV) compared to 0 to 2 fold increases in VAC domestic sheep. Two to 16 and 0 to 8 fold increases in antibodies titers to A2 and T10 cells, respectively, were detected in sera of both VAC groups. Sera of bighorn sheep with a history of respiratory disease and all domestic sheep had log2 leukotoxin neutralizing antibody titers of 4 to 14 in contrast to < or = 2 in sera of bighorn sheep without a history of respiratory disease. Neutralizing antibody titers of two bighorns without a history of respiratory disease in the VAC group increased from log2 0 to 5 in one and from 0 to 9 in the other 2 wk PV. Antibody increases in these animals were no longer evident at 16 wk PV while titers of animals with histories of disease remained relatively stable. The types and numbers of Pasteurella spp. isolated from nasal and pharyngeal swabs varied throughout the study without conclusive evidence of suppression of colonization. Although the animals were not experimentally challenged to determine the efficacy of the vaccine, one VAC and one NV bighorn sheep died following introduction of an A2 P. haemolytica strain when leukotoxin neutralizing antibodies had returned to pre-vaccination levels. This vaccine appeared to be safe for use in bighorn sheep and stimulated moderate but transient increases in antibody levels which should provide some protection against naturally occurring disease. A vaccine which would induce production of high and maintained antibodies against multiple strains of P. haemolytica would be valuable for use in bighorn sheep maintained in captivity or when captured for relocation.

Safety And Immunogenicity Of An Inactivated Hepatitis A Vaccine In Preschool Children

Young children in day care centers are an important source of hepatitis A virus (HAV) infection. The safety and immunogenicity of an inactivated HAV vaccine was evaluated in 57 children in day care centers. Nonimmune healthy children were given 0.5 mL of vaccine with subsequent doses: group A (28 children), second and third doses 1 and 2 months after the first; group B (29 children), second and third doses at 1 and 6 months. Antibody to HAV was measured before each dose and 8 months after the initial dose. All children developed antibody to HAV. Groups A and B had similar levels of antibody at 2 months; levels were lower in group B before the third dose and higher 8 months after the first dose. Local reactions after vaccination were reported in 17 children (29.8%). Minor systemic side effects that cleared spontaneously were observed in 27 children (47%).

Immunization with Tween-ether-treated SIV adsorbed onto aluminum hydroxide protects monkeys against experimental SIV infection

In order to examine the efficiency of an AIDS vaccine potentially acceptable for human use we have investigated a split vaccine. Since such vaccines are safe and efficient, they have been in use for many years to protect man against enveloped RNA viruses, e.g., influenza and measles. Seven rhesus monkeys were immunized at Week 0, 4, 8, and 16 by im injection of 2 ml of vaccine containing 140 μg of Tween-ether-disrupted SIVmac251/32H adsorbed onto aluminum hydroxide. The immunized animals and three nonvaccinated control monkeys were challenged 2 weeks after the last immunization by iv injection of 10 to 50 minimal monkey infectious doses of SIVmac251 /32H. Four of seven immunized animals did not show any signs of virus replication and therefore appeared to be protected. Nonvaccinated control animals and the vaccine failures showed a rise in their urinary neopterin concentrations 1 to 2 weeks after infection. At the end of the second week and thereafter, cocultures and polymerase chain reaction of their peripheral blood lymphocytes were positive. After the challenge, control animals and infected vaccinees showed a primary or secondary antibody response while antibody titers declined in virus-negative animals. Specific cytotoxic T-lymphocytes were not present prior to challenge, but were present in some animals thereafter. Therefore, these seem to reflect a response to viral replication rather than to immunization. Prior to challenge the CD4-positive lymphocytes of the peripheral blood of the four virus-negative animals only proliferated after exposure to the immunizing antigen. Thus, this reaction appears to predict protection.

Immunogenisity of the intradermal route of hepatitis B vaccination with the use of recombinant hepatitis B vaccine

In March 1987, 32 hospital employees were enrolled in a prospective trial of intradermal recombinant hepatitis B vaccination. Enrollees were given 0.1 ml of vaccine on days 1, 30, and 180. Two weeks after the third intradermal vaccination, 81%, or 26, of the enrollees showed seropositivity (⩾ 10 mIU antibody / ml) for hepatitis B surface antibody. Five of six nonresponders were given a fourth intradermal vaccination. Two additional seroconversions occurred, resulting in an overall conversion rate of 90% for recipients of up to four intradermal vaccine doses. Complications of vaccination were limited primarily to the occasional persistence (less than 6 months) of hyperpigmentation at the injection site. Administration of recombinant hepatitis B vaccine by the intradermal route proved to be a safe and effective method of vaccination. Cost savings of preexposure immunization with the intradermal versus the intramuscular route of vaccination were approximately $90 per enrollee. Efficacy and safety can be maximized by employing a fourth vaccine dose and routinely documenting seroconversion after vaccination. ( Am J Infect Control 1989;17:126–129)

Immune responses of humans to a human diploid cell strain of rabies virus vaccine: lymphocyte transformation, production of virus-neutralizing antibody, and induction of interferon.

Lymphocyte transformation, production of neutralizing antibody, and interferon activity of 20 healthy volunteers in response to a human diploid cell strain (HDCS) of rabies virus vaccine were studied. Ten vaccines received 1.0 ml of HDCS vaccine on days 0, 3, 7, and 14, and five of these volunteers received, in addition, 20 international units of human rabies immune globulin/kg of body weight on day 0. All 10 volunteers developed high titers of neutralizing antibody, and eight of the 10 had lymphocytes that were immunologically stimulated by HDCS rabies virus antigen. The interferon responses of eight vaccines to 1.0 ml of HDCS vaccine given intramuscularly on days 0 and 28 and of two vaccines to 1.0 ml of vaccine given intradermally in eight body sites on the same days were measured; low levels of interferon-like activity were found in eight of nine volunteers after the first vaccination, and no activity was found upon revaccination. The high titers of neutralizing antibody that developed did not correlate with lymphocyte stimulation or interferon-like activity, but it is true that all 20 volunteers did develop high titers of neutralizing antibody after 1.0 ml of HDCS vaccine was given intradermally.

Saponin Adjuvants. IV. Evaluation of The Adjuvant Quil a in the Vaccination of Cattle Against Foot-And-Mouth Disease

The saponin adjuvant Quil A has been investigated in the vaccination of cattle against foot-and-mouth disease. Using a Frenkel type vaccine a dose-response relationship has been established between Quil A and neutralizing antibody titres. Ten ml of vaccine was combined with 0, 50, 200, 800, and 3200 µg of Quil A. The combinations were each injected into 4 animals. The local reaction on the site of injection produced by injection of the vaccine alone and in combination with different doses of Quil A has been estimated. On this basis a therapeutical dose at 1 mg of Quil A has been estimated to combine maximum adjuvant effect with a minimum of adverse reactions. This dose has been tested in the vaccination of cattle with FMD vaccines derived from BHK suspension cell virus of type O and A respectively. The vaccines were tested in 10 ml and 5 ml doses with or without Quil A, and each in 4 animals. It is concluded that Quil A is a valuable adjuvant for use in the induction of neutralizing antibodies against foot-and-mouth disease in cattle.

Vibrio Fetus Infection in Bulls: Curative and Preventive Vaccination

SUMMARY Forty-one bulls positive to Vibio fetus venerealis have been vaccinated with a vaccine of killed V. fetus intestinalis organisms suspended in incomplete Freund adjuvant. Thirty (70 per cent) were found free of V. fetus after one injection, the remaining 11 (30 per cent) after a second injection. None of 288 V. fetus -negative bulls, serving in an infected area, became infected during the year following a single injection of 5 ml of vaccine. It can be concluded that vaccination of bulls is a safe and highly effective procedure for the treatment and prevention of V. fetus infection in bulls.

Effect of dose and time of vaccination on immune response of duck plague vaccine in ducks

Effect of dose and time of vaccination on immune response of duck plague vaccine in 90 (45 of 18-day-old and 45 of 35-day-old) Jinding ducklings was studied during the period from October 2002 to March 2003. Each of both age group (18-day-old and 35-day-old) was divided into three groups as A, B, C and D, E, F respectively, consisting of 15 ducklings in each. Each duckling of groups A and B was primarily vaccinated with 0.25 ml and 0.5 ml of duck plague vaccine (LRI, Mohakhali) intramuscularly at 18 days old respectively and could not be boosted due to the death of all the ducklings of both groups within 20 days of primary vaccination. Each duckling of group D and E received 0.5 ml and 1.0 ml of duck plague vaccine (LRI, Mohakhali) intramuscularly at 35 days old respectively and ducks of both the groups boosted with 1.0 ml of vaccine 5 months after primary vaccination. Groups C and F served as unvaccinated control. 14 days after booster vaccination ducks of group D, E and F were challenged with the virulent field isolate of duck plague virus @ 1.0 ml / duck IM (104 EID50 / dose). The ducklings of group D that were vaccinated primarily at 35 days old with 0.5 ml and boosted after 5 months with 1.0 ml of duck plague vaccine had significantly (p&lt; 0.01) higher PHA titres after 2 weeks of primary vaccination (38.4 ± 6.4), booster vaccination (153.6 ± 25.6) and challenge infection (281.6 ± 62.71) in comparison to control group (≤4, ≤4 and 20.0 ± 2.3 respectively) and all the ducks survived (100%) after challenge. The ducklings of group E that were vaccinated primarily at 35 days old and boosted after 5 months of primary vaccination with 1.0 ml of duck plague vaccine had also significantly (p&lt; 0.01) higher PHA titres after two weeks of booster vaccination (76.8 ± 12.8) and challenge infection (153.6 ± 25.6) in comparison to control group, but only 8 (53.3%) ducks could protect the challenge infection with virulent duck plague virus. It may be concluded that ducklings below 30 days of age should not be vaccinated with duck plague vaccine. It also may be proposed that primary vaccination at 35 days old with duck plague vaccine (LRI, Mohakhali) @ 0.5 ml / duckling and booster vaccination after 5 months of primary vaccination @ 1.0 ml could be practiced for better immune response against duck plague.Key words: effect; dose; age; immune response; duck plague vaccine; ducksdoi: 10.3329/bjvm.v2i2.2542Bangl. J. Vet. Med. (2004). 2 (2): 117-119

Antibody Responses in Nasal Secretions and Serum of Elderly Persons Following Local or Parenteral Administration of Inactivated Influenza Virus Vaccine

Summary Nasal secretion and serum neutralizing antibody responses of 22 elderly persons to vaccination with a bivalent inactivated influenza virus vaccine by local or parenteral routes were compared. Each 1.0 ml of vaccine contained 300 chicken cell agglutination (CCA) units each of A2/Taiwan/1/64 and A2/Japan/170/62, and 600 CCA units of B/Mass/3/66 influenza virus antigens. The titers and duration of IgA antibody in nasal secretions were higher and appeared to persist longer following repeated nasopharyngeal vaccination than after a single subcutaneous immunization. The frequency and duration of serum antibody responses induced by local administration of vaccine were not significantly different from those seen following parenteral vaccination.

Serologic Response in Man to Varying Amounts of Inactivated Epidemic Typhus Vaccine.

SummaryThree hundred and sixty-nine Marine Corps recruits, initially without either complement fixing or toxin neutralizing epidemic typhus antibodies, were studied to determine their antibody response to subcutaneous injection of decreasing doses of commercially produced epidemic typhus vaccine administered in 1 or 2 doses of 1 ml each. When immunized with either 1 or 2 doses of undiluted vaccine or with 1 dose of vaccine diluted 1:2 or 1:4 91 to 100% of the 194 marines responded by developing either complement fixing or toxin neutralizing antibodies, or both. About 1/3 of 116 marines who received 1 dose of vaccine diluted 1:16 or 1:64 developed these antibodies. A single dose of vaccine diluted 1:256 elicited demonstrable antibodies in 15% or 9 of 59 men. These results suggested that the amount of antigen contained in 2.0 ml of vaccine required in the basic course of the immunization regimen was more than was needed to accomplish reasonable antibody responses in man. Accordingly, the primary immunizatio...

A Field Trial of Inactivated Measles Virus Vaccine in Young School Children

A concentrated, alum-containing, formalin-inactivated measles virus vaccine was evaluated in a double-blind field trial conducted in young school children. Vaccine was administered at random to 296 five- and six-year olds and placebo to 286. The dosage schedule consisted of three intramuscular injections of 0.5 ml of vaccine or placebo at intervals of one and three weeks. Measles was prevalent in the study population during the immunization period and for three months thereafter as well as from the 18th through the 27th months of follow-up. During the immediate postvaccir ation challenge vaccine effectiveness was estimated at 94% while during the late postimmunization challenge, effectiveness had declined to 57%. Nevertheless, during the latter period, the proportion of mild cases was considerably higher among vaccinees than controls.