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Natural boosting of vaccine-induced immunity with mild or subclinical disease


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: Epidemiol Infect 2000 Apr;124(2):263-71 Related Articles, Help

Secondary measles vaccine failures identified by measurement of IgG avidity: high occurrence among teenagers vaccinated at a young age.

Paunio M, Hedman K, Davidkin I, Valle M, Heinonen OP, Leinikki P, Salmi A, Peltola H.

Department of Public Health, University of Helsinki, Finland.

Failure to seroconvert (primary vaccine failure) is believed to be the principal reason (approx. > 95%) why some vaccinees remain susceptible to measles and is often attributed to the persistence of maternal antibodies in children vaccinated at a young age. Avidity testing is able to separate primary from secondary vaccine failures (waning and/or incomplete immunity), but has not been utilized in measles epidemiology. Low-avidity (LA) and high-avidity (HA) virus-specific IgG antibodies indicate primary and secondary failure, respectively. Measles vaccine failures (n = 142; mean age 10.1 years, range 2-22 years) from an outbreak in 1988-9 in Finland were tested for measles-virus IgG avidity using a protein denaturating EIA. Severity of measles was recorded in 89 failures and 169 non-vaccinees (mean age 16.2 years, range 2-22 years). The patients with HA antibodies (n = 28) tended to have clinically mild measles and rapid IgG response. Among failures vaccinated at < 12, 12-15 and > 15 months of age with single doses of Schwarz-strain vaccine in the 1970s, 50 (95% CI 1-99), 36 (CI 16-56) and 25% (CI 8-42) had HA antibodies, respectively. When a single measles, mumps and rubella (MMR) vaccine had been given after 1982 at 15 months of age, only 7% (CI 0-14) showed HA antibodies. Omitting re-vaccinees and those vaccinated at < 15 months, Schwarz-strain recipients had 3.6 (CI 1.1-11.5) higher occurrence of HA responses compared to MMR recipients. Apart from one municipality, where even re-vaccinees had high risk of primary infection, 89% (CI 69 to approximately 100) of the infected re-vaccinees had an HA response. Secondary measles-vaccine failures are more common than was more previously thought, particularly among individuals vaccinated in early life, long ago, and among re-vaccinees. Waning immunity even among individuals vaccinated after 15 months of age, without the boosting effect of natural infections should be considered a relevant possibility in future planning of vaccination against measles.

PMID: 10813152 [PubMed - indexed for MEDLINE]

AN: 20271260


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9951981&dopt=Abstract

 
Pediatr Infect Dis J 1999 Jan;18(1):53-7 Related Articles, Books, LinkOut
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Poor serologic responses five to seven years after immunization with high and standard titer measles vaccines.

Whittle H, Aaby P, Samb B, Cisse B, Kanteh F, Soumare M, Jensen H, Bennett J, Simondon F.

MRC Laboratories, Banjul, The Gambia. whittle@commit.gm

BACKGROUND: Few data exist on the persistence of measles antibodies after vaccination of West African infants. Therefore we examined measles antibody titers 5 to 7 years after children in rural Senegal had received high titer Edmonston-Zagreb (EZ-HT), high titer Schwarz (SW-HT) or standard titer Schwarz (SW-STD) measles vaccines in infancy. METHODS: Children had received either high titer vaccines at 5 months of age or standard titer at 10 months of age. Finger prick blood samples were tested for measles antibody 5 to 7 years later by the hemagglutinin inhibition test. RESULTS: Persistence of antibody after high titer vaccines was poor with the result that 39 and 50% of the EZ-HT and the SW-HT groups had low titers of hemagglutinin inhibition measles antibodies (< or =125 mIU/ml). Nineteen percent of the children in the SW-STD group had low titers which is a lower prevalence than in the high titer groups [relative risk (95% confidence intervals), 0.05 (0.28 to 0.88) vs. EZ-HT; relative risk, 0.38 (0.22 to 0.66) vs. SW-HT]. Geometric mean (95% confidence interval) antibody titers in children with detectable values were 616 (435 to 871) in the EZ-HT, 1106 (616 to 1866) in the SW-HT and 1271 (871 to 1741) mIU/ml in the SW-STD groups, respectively. Multivariant regression analysis showed that mean titers were 2.00 (1.03 to 3.89) times higher for children with low prevaccination antibody titers (< or =125 mIU/ml) and 3.06 (1.90 to 4.94) times higher if blood was collected in the rainy season. INTERPRETATION: Given the rapid decline in antibody titers over a 5- to 6-year period in an area where measles vaccine coverage was high, it seems likely that multiple dose immunization schedules will be needed in the future to maintain protective antibody concentrations (>125 mIU/ml) in West Africa. The role of subclinical boosting by exposure to natural measles and the possible role of malaria, which increases immunoglobulin turnover, in influencing long term antibody persistence after vaccination deserve further investigation.

PMID: 9951981 [PubMed - indexed for MEDLINE]

AN: 99135452


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10023894&dopt=Abstract

 
Lancet 1999 Jan 9;353(9147):98-102 Related Articles, Books, LinkOut
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Effect of subclinical infection on maintaining immunity against measles in vaccinated children in West Africa.

Whittle HC, Aaby P, Samb B, Jensen H, Bennett J, Simondon F.

MRC Laboratories, Fajara, Banjul, The Gambia. whittle@commit.gm

BACKGROUND: Despite a high coverage with measles vaccines in parts of west Africa, epidemics of measles occur with reduced severity in an increasing proportion of older children who have been vaccinated. We examined the effect of exposure to natural measles on immunity in vaccinated children. METHODS: Our study was carried out in 1992 during an epidemic of measles in Niakhar, a rural area of Senegal with about 27,000 inhabitants who mostly live in compounds that include several households; within each household people live in different huts. Vaccine coverage in Niakhar was 81% at the time of our study. We measured haemagglutinin-inhibiting antibody at exposure and twice thereafter (after 4-5 weeks and at 6 months) in 36 vaccinated and 87 unvaccinated children. The frequency of measles and subclinical measles--defined as a four-fold or greater rise in antibody titre without clinical signs or symptoms--was related to intensity of exposure according to whether the index case was in the same hut, household, or compound. FINDINGS: Clinical measles occurred in 20 (56%) of 36 unvaccinated children and in one (1%) of 87 vaccinated children. Subclinical measles occurred in 39 (45%) of 86 vaccinated children who were exposed to measles and in four (25%) of 16 unvaccinated children. The frequency was inversely related to pre-exposure antibody concentration (p<0.001 for trend) and directly related to intensity of exposure (p=0.002 for trend). Antibody concentrations in subclinical cases increased on average by 45-fold and remained raised for at least 6 months. INTERPRETATION: Increased antibody titre after subclinical measles may be common in vaccinated children in West Africa where the intensity of exposure is high. As measles vaccination coverage increases, the circulation of wild measles will decrease, and vaccine-induced antibody is less likely to be boosted. Thus, new epidemics, albeit milder in form, may occur in vaccinated areas which should be recognised in campaigns to eradicate measles.

PMID: 10023894 [PubMed - indexed for MEDLINE]

AN: 99146499


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10195680&dopt=Abstract

 
Int J Epidemiol 1999 Feb;28(1):147-51 Related Articles, Books, LinkOut
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Seroconversions in unvaccinated infants: further evidence for subclinical measles from vaccine trials in Niakhar, Senegal.

Bennett J, Whittle H, Samb B, Cisse B, Simondon F, Aaby P.

The Task Force for Child Survival and Development, The Carter Center, Atlanta, GA 30307, USA.

BACKGROUND: Increases in measles antibodies without rash-illnesses have been documented in previously vaccinated children exposed to measles cases. The phenomenon has been incompletely evaluated in young unvaccinated infants with immunity of maternal origin. METHODS: Monthly cohorts of newborns were prospectively randomized to vaccine and placebo control groups during a trial of high-titre vaccines in Niakhar, Senegal. Measles antibodies were assayed in blood samples of enrolled children collected at 5 months old, when controls received a placebo injection, and at 10 months, when the placebo group was given measles vaccine. Intensive prospective surveillance for measles was conducted throughout the trial. RESULTS: One-fifth (n = 53) of the placebo controls seroconverted, with known exposure to a measles case in only three of them. None of the seroconverters developed a measles-like rash. Sixteen-fold or greater increases in titres were noted in about one-quarter of them. Compared with placebo controls who did not seroconvert, seroconverters were more likely to have had exposure to a measles case and to travel, more likely to be boys than girls, and had significantly lower baseline antibody titres. Measles was endemic in the study area throughout the trial. Seroconversions did not adversely effect subsequent nutritional indices or mortality. CONCLUSIONS: Although laboratory errors and inadvertent injection of vaccine rather than placebo may have played some role, they do not fully explain the above observations, which are consistent with subclinical measles in the seroconverters. The possible role of subclinical measles in occult transmission, its potential effect on the type and duration of subsequent immunity, and its impact on response to primary vaccination need to be determined.

Publication Types:
  • Clinical Trial
  • Randomized Controlled Trial


PMID: 10195680 [PubMed - indexed for MEDLINE]

AN: 99210055


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10448940&dopt=Abstract

 
Prev Vet Med 1999 Jul 20;41(2-3):105-18 Related Articles, Books, LinkOut

The effect of subclinical experimental Cowdria ruminantium infection in ewes on the growth and milk consumption of pre-weaning lambs.

Martinez TA, Meltzer MI, Perry BD, Burridge MJ, Mahan SM.

Department of Pathobiology, College of Veterinary Medicine, University of Florida, Gainesville 32611, USA. sumanmah@samara.co.zw

An alternative control option for heartwater (Cowdria ruminantium infection) is the establishment and maintenance of endemic stability which would lessen the existing dependence on acaricides. In an endemically stable state, animals become infected by vaccination or natural challenge at an early age, following which the immunity so created is boosted by continuing tick challenge. In this study, growth rates, health and hematological parameters were monitored at regular intervals for lambs born to two matched groups of ewes until weaning at 4 mo of age. One group of ewes was infected multiple times with Cowdria ruminantium; the other group remained uninfected. The overall mean leucocyte count of lambs born to infected ewes was significantly lower than that of lambs born to uninfected ewes (P=0.04). However, there were few other significant differences in the other hematological data between the two groups. The mean birth weight of single lambs born to uninfected ewes (4.6 kg) was significantly higher than the mean birth weight of single lambs born to infected ewes (4.4 kg) (P=0.02). Trends in milk consumption and growth rates were similar for the two groups, with few significant differences detected. Likewise, there were no significant differences in the incidences of health problems or pre-weaning mortalities between the two groups of lambs. The results of this study indicate that there is no detectable effect on productivity of pre-weaning lambs when their dams are carriers of C. ruminantium--a situation likely to occur in an endemically stable state. Hence, maintenance of endemic stability would be a suitable control option for heartwater.

PMID: 10448940 [PubMed - indexed for MEDLINE]

AN: 99376170


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10588085&dopt=Abstract

 
Am J Epidemiol 1999 Dec 1;150(11):1238-49 Related Articles, Books, LinkOut

Modeling the impact of subclinical measles transmission in vaccinated populations with waning immunity.

Mossong J, Nokes DJ, Edmunds WJ, Cox MJ, Ratnam S, Muller CP.

Department of Biological Sciences, University of Warwick, Conventry, England.

An increasing body of evidence suggests that a substantial proportion of individuals who respond to measles vaccine display an antibody boost accompanied by mild or no symptoms on exposure to wild virus. It is unknown whether this emerging class of individuals can support transmission. The epidemiologic consequences of vaccinated individuals able to transmit virus are investigated using a mathematical model. Parameters for this model are estimated using regression analysis on a Canadian serologic data set. The authors confirm that neutralizing antibodies are decaying significantly in absence of circulating virus. Based on a protective threshold plaque reduction neutralization (PRN) titer of 120, the authors estimate the mean duration of vaccine-induced protection in absence of reexposure to be 25 years (95% confidence interval (CI) 18, 48). After long-term absence of circulating virus, the mathematical model predicts that 80% (95% CI 65, 91) of all seroconverted vaccinees have titers below the protective threshold. In this case, elimination of measles virus cannot be achieved by a single-dose routine vaccination strategy if the basic reproduction number in vaccinated individuals exceeds 1.24 (95% CI 1.10, 1.53). For this reason, there is a need to establish the intensity and duration of infectiousness in vaccinated individuals.

PMID: 10588085 [PubMed - indexed for MEDLINE]

AN: 20053306


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9796064&dopt=Abstract

 
Vaccine 1998 Dec;16(20):2052-7 Related Articles, Help
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Vaccine-induced measles virus antibodies after two doses of combined measles, mumps and rubella vaccine: a 12-year follow-up in two cohorts.

Davidkin I, Valle M.

National Public Health Institute, Helsinki, Finland. Irja.Davidkin@ktl.fi

In Finland, a two-dose vaccination programme against measles, mumps and rubella (MMR) was begun in 1982. The programme with high coverage (97-98%) has eliminated these three diseases from Finland. The aim of the present study was to follow up the kinetics of measles virus antibodies in MMR vaccinated cohorts. We have followed the kinetics of measles virus antibody levels induced by vaccination in the same individuals immunized with their first MMR vaccine in 1982. After 12 years 80% of the original children remained available for sampling. Antibodies to measles virus were measured by haemagglutination inhibition (HI) and plaque reduction neutralization (NT) techniques. The primary dose induced 99.4% seroconversion for measles with a geometric mean HI antibody titre (GMT) of 1/269 (+/- 219), equivalent to 4304 mIU (milli-International Units) ml-1 in group A. The 12-year follow-up specimens showed a measles seropositivity rate of 100% as assayed with the HI and NT tests with a mean HI antibody titre of 1/39 (+/- 54), equivalent to 624 mIU ml-1. The vaccination-induced measles virus antibodies decline in the absence of natural booster infections. It is important to follow how long the protection achieved by the present vaccine programme will last after elimination of indigenous measles.

Publication Types:
  • Clinical Trial


PMID: 9796064 [PubMed - indexed for MEDLINE]

AN: 99012156


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9564478&dopt=Abstract

 
Clin Infect Dis 1998 Apr;26(4):933-7 Related Articles, Books, LinkOut

Increases in levels of antibody to hepatitis B surface antigen in an immunized population.

Bulkow LR, Wainwright RB, McMahon BJ, Parkinson AJ.

Arctic Investigations Program, Centers for Disease Control and Prevention, Anchorage, Alaska.

Hepatitis B vaccine is effective in preventing infection with hepatitis B virus (HBV), but its duration of protection is unknown. To examine the effect of exposure to HBV on an immunized population, data were analyzed from a cohort of Alaska Natives who were immunized and then followed up annually for 10 years. A boost in antibody to hepatitis B surface antigen (anti-HBs) was defined as a fourfold rise in levels to > or = 20 mIU/mL that was not accompanied by the presence of antibody to hepatitis B core antigen or attributable to interim vaccination. During 10 years of follow-up, 8.2% of 1,595 vaccines had boosts in anti-HBs. Persons with boosts did not differ significantly from those without boosts in terms of age, gender, village, initial level of anti-HBs, or level of anti-HBs before the boost. These results underscore the continued exposure to HBV among vaccinees and the continued protection against disease that the vaccine provides.

PMID: 9564478 [PubMed - indexed for MEDLINE]

AN: 98225665


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9447754&dopt=Abstract

 
: Acta Paediatr Jpn 1997 Dec;39(6):663-8 Related Articles, Books, LinkOut

High incidence of breakthrough varicella observed in healthy Japanese children immunized with live attenuated varicella vaccine (Oka strain).

Takayama N, Minamitani M, Takayama M.

Department of Pediatrics, Tokyo Metropolitan Komagome Hospital, Japan.

In order to know the rate of occurrence of varicella among vaccinees (breakthrough varicella: BV), questionnaire postcards were sent to 593 healthy children who had received varicella vaccine (Oka strain) from March 1987 to December 1989. The questionnaire survey was repeated once a year until January 1996. The annual attack rate from the 1st to 3rd questionnaire was approximately 12%: however, from the 5th to 8th one it was 1-4%. To February 1996, the cumulative attack rate was 157/459 (34.2%). This rate was comparable to that among vaccinees who had confirmed seroconversion; namely, 51/132 (38.6%). These rates are much higher than those reported by other authors. All BV cases were clinically mild; even subjects who had received the vaccine 7 years prior to the disease showed mild symptoms. The high incidence may be partly explained by the regional epidemiology of varicella. The decrease in annual incidence with time after vaccination may be due to the following reasons: some vaccinees remained free from BV owing to reinforcement of their immunity from subclinical infection of varicella-zoster virus (VZV) and others from diminution of opportunity for exposure to VZV with increasing age. Varicella vaccine seems to be effective in modifying the symptoms of varicella, but not potent enough in protecting from VZV infection.

PMID: 9447754 [PubMed - indexed for MEDLINE]

AN: 98109060


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8758397&dopt=Abstract

 
Zhonghua Liu Xing Bing Xue Za Zhi 1996 Apr;17(2):70-2 Related Articles, Books, LinkOut

[Study on the subclinical infection of the recipients of measles vaccine]

[Article in Chinese]

Wu T, Wang SL, Xiang YZ.

Sanitary and Anti-epidemic Station, Zhejiang Province, Hangzhou.

Through observation to subclinical infection of the 71 children who had been inoculated against measles 12 years ago and then exposed to natural measles from three classes at a primary school, we have noticed: (1) Subclinical infection did exist among the crowd who were inoculation against measles; The rate of subclinical infection of the three classes was between 18.5%-75.0%, with an average of 45.1%. (2) The level of the HI Ab titer was between 1:2-1:16. The peak level was between 1:2 and/or 1:4. So the rate of subclinical infection who had been inoculation against measles but later exposed to natural measles would depend on the proportion of those whose titer of HI Ab was 1:2-1:4 in the crowd. (3) The epidemiological significance of subclinical measles infection lies in that it can actively keep and consolidate the level of immunity to certain extent in a crowd who had been inoculation against measles.

PMID: 8758397 [PubMed - indexed for MEDLINE]

AN: 96335850


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8923290&dopt=Abstract

 
: J Med Virol 1996 Nov;50(3):249-53 Related Articles, Books, LinkOut

Measles immunity and response to revaccination of a young adult population in Israel.

Mendelson E, Duvdevani P, Varsano N, Lerman Y, Slepon R, Dagan R, Cohen D, Danon Y, Shohat T.

Central Virology Laboratory, Chaim Sheba Medical Center, Tel-Hashomer, Israel.

In order to evaluate the true immune status and the effect of revaccination on a young adult population, we collected serum samples from 289 military recruits who were vaccinated during an outbreak in 1991. Most vaccinees, age 18-25 years, had apparently been immunized once before as infants. Sera collected just prior to the vaccination and 14 and 28 days afterwards were tested for measles antibodies by hemagglutination inhibition (HI) and enzyme-linked immunosorbent assay (ELISA)-IgM. Before vaccination, 46 (15.9%) of the subjects had no HI antibodies, (< 1:4) and 48 (16.6%) had borderline (1:4) HI titer. Following vaccination, only ten (3.5%) remained negative and 19 (6.6%) had borderline titer. The increase in HI antibody titer was inversely proportional to the prevaccination titer, and 159 subjects (55.0%) showed no increase at all. The geometric mean titer (GMT) rose from 9.14 to 21.47. Among the prevaccination-negative subjects (HI < 1:4) 28 (60.9%) reached a postvaccination titer of > or = 1:8, and eight (17.4%) reached a titer of 1:4. Twelve (26.1%) of the negative subjects seroconverted and developed IgM, 16 (35%) seroconverted without IgM, and 18 (39%) remained negative and did not develop IgM. A group of eight vaccinees with prevaccination titer of > or = 1:4 developed IgM. Some were probably infected by the circulating wild-type virus prior to the vaccination. Thus, a total number of 20 of the 289 subjects studied (6.9%) had true negative preimmune status as judged by the IgM test. However, the vaccination campaign prevented further measles cases, apparently by increasing the population's immunity, particularly in individuals with very low titers or without measles antibodies.

PMID: 8923290 [PubMed - indexed for MEDLINE]

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7827424&dopt=Abstract

 
Math Biosci 1994 Nov;124(1):59-82 Related Articles, Books, LinkOut

Waning immunity and its effects on vaccination schedules.

Rouderfer V, Becker NG, Hethcote HW.

School of Statistics, La Trobe University, Bundoora, Vic, Australia.

A relatively comprehensive age-specific transmission model is used to determine the effect of various factors on the optimal vaccination ages in one-dose and two-dose vaccination schedules. Motivated by the situation for measles, the model allows the duration of immunity of newborns to depend on the level of immunity of the mother at the time of the birth and allows for waning immunity as well as boosting of immunity by exposure to the disease. It is found that a significant amount of waning of disease-acquired immunity is plausible when boosting occurs but this is not an important factor in determining optimal vaccination schedules. On the other hand, plausible rates of loss of vaccine-induced immunity can have a substantial effect on the optimal vaccination schedule, particularly when there is no boosting of immunity. For two-dose schedules the optimal vaccination ages depend significantly on the level of vaccination coverage achieved. In the presence of plausible rates of loss of vaccine-induced immunity for measles, it is found that the vaccination coverage required to eradicate the disease is substantially higher than previously suggested.

PMID: 7827424 [PubMed - indexed for MEDLINE]

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8488803&dopt=Abstract

 
Am J Dis Child 1993 May;147(5):558-60 Help

Measles, mumps, and rubella antibodies in vaccinated Baltimore children.

King JC Jr, Lichenstein R, Feigelman S, Luna C, Permutt TJ, Patel J.

Department of Pediatrics, University of Maryland School of Medicine, Baltimore.

OBJECTIVE--To determine quantitative measles, mumps, and rubella serum antibody levels as a function of time since vaccination in a sample of vaccinated Baltimore children. DESIGN--Cross-sectional serologic survey. SETTING--Pediatric outpatient departments at the University of Maryland Medical Center, Baltimore. PARTICIPANTS--One hundred seventy children, ranging in age from 1.5 through 16 years, who had measles, mumps, and rubella vaccination between ages 12 and 18 months. RESULTS--Serum antibody levels to measles and rubella declined with increasing time since vaccination. However, no such decline in antibody levels to mumps was observed. Children who were vaccinated between ages 12 and 14 months did not have lower antibody levels than children who were vaccinated at age 15 months or older. CONCLUSIONS--In areas free from natural disease, antibody levels resultant from measles, mumps, and rubella vaccine are likely to decline with advancing age. Revaccination with measles, mumps, and rubella vaccine may boost falling antibody titers.

PMID: 8488803 [PubMed - indexed for MEDLINE]

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7687111&dopt=Abstract

 
: Ann Trop Paediatr 1993;13(2):153-8 Related Articles, Books, LinkOut

Persistence of antibody at 18 months following vaccination of young Gambian infants with PRP-OMPC Haemophilus influenzae type b conjugate vaccine.

Mulholland EK, Todd J, Rowe M, Campbell H, Byass P, Vella PP, Ahonkhai VI, Greenwood BM.

Medical Research Council Laboratories, The Gambia, West Africa.

The rate of decline in anti-PRP antibody levels was measured in two groups of Gambian children who had been given PRP-OMPC at 1 and 3 months or 2 and 4 months of age. In the younger group (n = 70), the geometric mean titre fell from 1.32 micrograms/ml at 4 months to 0.44 micrograms/ml at 18 months. In the older group (n = 54), the geometric mean titre fell from 1.18 micrograms/ml at 5 months to 0.46 micrograms/ml at 18 months. The proportion of vaccinated children with antibody levels over 1.0 microgram/ml fell from 54% 1 month after the second dose of vaccine to 27% at the age of 18 months, while the proportion with levels over 0.15 micrograms/ml fell from 82% to 60%, with no significant differences observed between the vaccination groups. For those children who did not show evidence of environmental boosting, the half-life of anti-PRP antibody was about 100 days. This did not differ between the groups. These findings suggest that to provide lasting immunity PRP-OMPC should be given with a late booster dose at 12-15 months, as is the current practice in the USA. The need for a late booster dose may limit the value of this vaccine in developing countries where vaccination of children is difficult after the 1st year of life.

Publication Types:
  • Clinical Trial
  • Randomized Controlled Trial


PMID: 7687111 [PubMed - indexed for MEDLINE]

AN: 93319237


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2156941&dopt=Abstract

 
J Infect Dis 1990 Apr;161(4):661-6 Related Articles, Books, LinkOut

Live attenuated varicella vaccine: protection in healthy adults compared with leukemic children. National Institute of Allergy and Infectious Diseases Varicella Vaccine Collaborative Study Group.

Gershon AA, Steinberg SP.

Department of Pediatrics, Columbia University, College of Physicians & Surgeons, New York City.

Protection against varicella infection was assessed in leukemic children and healthy young adults who were immunized with live attenuated varicella vaccine. Attack rates of breakthrough infection following household exposure to varicella in 102 children and 26 adults were similar whether one or two doses of vaccine had been given. The mild breakthrough illness was also similar after one or more doses. Specific antibody titers were similar 1 year after immunization whether individuals had received one or two doses. Humoral and cell-mediated immunity to varicella-zoster virus (VZV) was lower in these vaccinees than in persons who had experienced natural varicella infection. Protection after natural infection in adult family members exposed to varicella was superior to that in vaccinees; none developed varicella infection. These observations suggest that immunization induces less protection than does natural disease in leukemic children and young adults. This may be partly due to the nature of the vaccine virus, but because responses of adults were similar to those of leukemic children, it suggests also that both of these groups have impaired immune responses to VZV. Boosting of humoral immunity after exposure to VZV was common and was observed in healthy adults with past natural infection and in vaccinated adults and leukemic children.

PMID: 2156941 [PubMed - indexed for MEDLINE]

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2815970&dopt=Abstract

 
Vaccine 1989 Aug;7(4):345-8 Related Articles, Books, LinkOut

Subclinical measles infection in vaccinated seropositive individuals in arctic Greenland.

Pedersen IR, Mordhorst CH, Glikmann G, von Magnus H.

Institute of Medical Microbiology, University of Copenhagen, Denmark.

Measles vaccination was performed in the arctic district of Scoresbysund, Greenland in 1968, which had never been exposed to natural measles. More than 90% of the total population was vaccinated and a 94-100% seroconversion was obtained. During a serological survey to examine the immunity status of the vaccinees, it was discovered that a temporary increase in measles antibodies took place in the majority of the population 2-4 years after the vaccination. This was not accompanied by clinically observed measles. Most likely, it was due to an inapparent measles infection in a population considered highly immune after vaccination.

PMID: 2815970 [PubMed - indexed for MEDLINE]

AN: 90051677


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2440712&dopt=Abstract

 
Exp Parasitol 1987 Aug;64(1):64-70 Related Articles, Books, LinkOut

Plasmodium falciparum: sporozoite boosting of immunity due to a T-cell epitope on a sporozoite vaccine.

Hoffman SL, Cannon LT Sr, Berzofsky JA, Majarian WR, Young JF, Maloy WL, Hockmeyer WT.

Plasmodium falciparum: Sporozoite boosting of immunity due to a T-cell epitope on a sporozoite vaccine. Experimental Parasitology 64, 64-70. The impact of a malaria sporozoite vaccine may be enhanced if protective immunity elicited by the vaccine is boosted by natural exposure to sporozoites. For this to occur, a helper T lymphocyte epitope present on the vaccine must be shared by sporozoites. These studies show that T cells from mice immunized with R32tet32, the Plasmodium falciparum sporozoite vaccine candidate, recognize an epitope of less than or equal to 7 amino acids derived from the circumsporozoite protein repeat region of R32tet32, as well as an epitope on the tet32 fusion protein tail of R32tet32. Exposure of R32tet32 immunized animals to P. falciparum sporozoites elicits a significant secondary antibody response which suggests that humans who are immunized and respond to this vaccine may be boosted by field exposure to sporozoite infected mosquitoes.

PMID: 2440712 [PubMed - indexed for MEDLINE]

AN: 87276374


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3030864&dopt=Abstract

 
Dev Biol Stand 1986;65:89-93 Related Articles, Books, LinkOut

The combination measles, mumps, rubella and varicella vaccine in healthy children.

Arbeter AM, Baker L, Starr SE, Plotkin SA.

A clinical trial was conducted to compare the combination measles, mumps, rubella, varicella vaccine (MMRV) and the standard measles, mumps, rubella vaccine and subsequent varicella vaccine (MMR + V) in 15 to 17 month old healthy children. Both the MMRV and MMR + V schedules stimulated virtually 100% seroconversion for all component viruses. Mean antibody titers were similar for each virus component in the two vaccine groups. Clinical reactivity post immunization was also similar with 25-29% morbilliform rashes, 12-25% mild papulovesicular (varicella) rashes, and 12.5-18% temperature elevations above 101 degrees F. Antibodies to measles, mumps, and rubella viruses were persistent in 8/10 originally seronegative MMRV vaccinees and 5/5 MMR + V recipients tested. On MMRV recipient had a household exposure to chickenpox during the year postvaccination that resulted in a subclinical boost in varicella antibody titer. Two children in the MMR + V group had close varicella exposures: one developed mild varicella (20 lesions). There were no known exposures to natural measles, mumps, or rubella. Three of four MMRV vaccinees with low titer antibody to varicella prior to immunization had greater than four-fold rises in antibodies. The combination measles, mumps, rubella, varicella vaccine is an immunogenic, safe and cost effective approach to varicella immunization of healthy children.

Publication Types:
  • Clinical Trial
  • Controlled Clinical Trial


PMID: 3030864 [PubMed - indexed for MEDLINE]

AN: 87162921


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3778422&dopt=Abstract

 
Biken J 1986 Mar;29(1):19-26 Related Articles, Books, LinkOut

A long-term follow-up study on the efficacy of further attenuated live measles vaccine, Biken CAM vaccine.

Isomura S, Morishima T, Nishikawa K, Hanada N, Rahman M, Terashima M, Kido S, Ueda S, Takahashi M.

Antibody persistence was measured in 39 children in an open community 12-13 years after immunization against measles with further attenuated live vaccine, Biken CAM. Serum samples of the children taken every two or three years after vaccination had higher, lower, or the same HI antibody titers as those in samples taken 6 weeks after vaccination. These differences reflected a decrease in the titer in some children and subclinical natural reinfection in others. However, all the children still retained detectable antibody in 12 or 13 years after vaccination, indicating long-term persistence of immunity after immunization with Biken CAM vaccine. For evaluation of the protective efficacy of the vaccine, matched controls were studied during the same period. Serological examination revealed that 97.5% of the controls were infected with measles and contracted the disease. In contrast, none of the vaccinees developed clinical infection after close contact with measles patients.

PMID: 3778422 [PubMed - indexed for MEDLINE]

AN: 87048699


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=4001742&dopt=Abstract

 
Rev Infect Dis 1985 Mar-Apr;7 Suppl 1:S91-4 Related Articles, Books, LinkOut

Duration of immunity after rubella vaccination: a long-term study in Switzerland.

Just M, Just V, Berger R, Burkhardt F, Schilt U.

In Switzerland 319 of 594 young women seronegative for rubella antibody vaccinated at 15-25 years of age against rubella with the Cendehill vaccine strain were retested 15 years later with three tests (hemagglutination inhibition, enzyme-linked immunosorbent assay, and a neutralization technique) for the presence of rubella antibodies. For 307 women rubella antibodies were still detectable by all three techniques. For nine women rubella antibodies were demonstrable by only one or two tests. Only three vaccinees were seronegative by all three tests. These three women also showed no booster response after challenge with the vaccine strain. The high percentage of women with persistent rubella antibodies 15 years after vaccination might be explained in part by the presence of subclinical reinfections due to a wild rubella virus.

PMID: 4001742 [PubMed - indexed for MEDLINE]

AN: 85218138


http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6151692&dopt=Abstract

 
Philos Trans R Soc Lond B Biol Sci 1984 Nov 13;307(1131):99-115 Related Articles, Books, LinkOut

Perspectives for malaria vaccination.

Miller LH, David PH, Hadley TJ.

The need for vaccines to relieve the current global resurgence of malaria is apparent. Immunity is specific for each species of human malaria and for each stage in the life cycle. Once protective immunogens have been identified for one species, the homologous molecules in other species may lead to protection. The usefulness of a particular immunogen will be determined, in part, by its antigenic diversity in the population and the potential for boosting during natural infection. Successful immunization with malarial antigens may require adjuvants to induce effective, long-lived immunity. If different vaccines become available against each stage in the life cycle, then the composition of a particular vaccine may be tailored for different objectives: protection for short periods (for example, during epidemics and for tourists), decrease in disease and death, and malaria eradication.

Publication Types:
  • Review


PMID: 6151692 [PubMed - indexed for MEDLINE]

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