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Subclinical or mild disease among the vaccinated

Mild or subclinical disease among the vaccinated

N Engl J Med 2001 Mar 29;344(13):955-60 Related Articles, Books, LinkOut

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The effectiveness of the varicella vaccine in clinical practice.

Vazquez M, LaRussa PS, Gershon AA, Steinberg SP, Freudigman K, Shapiro ED.

Department of Pediatrics, Yale University School of Medicine, New Haven, Conn 06520-8064, USA.

BACKGROUND: A live attenuated varicella vaccine was approved for use in the United States in March 1995 and is recommended for all susceptible persons 12 months of age or older. METHODS: To assess the effectiveness of the varicella vaccine, we conducted a case-control study with two controls per child with chickenpox, matched according to both age and pediatric practice. Children with potential cases of chickenpox were identified by active surveillance of pediatric practices in the New Haven, Connecticut, area. Research assistants visited the children on day 3, 4, or 5 of the illness, assessed the severity of the illness, and collected samples from lesions to test for varicella-zoster virus by polymerase chain reaction (PCR). RESULTS: From March 1997 through November 2000, data collection was completed for 330 potential cases, of which 243 (74 percent) were in children who had positive PCR tests for varicella-zoster virus. Of the 56 vaccinated children with chickenpox, 86 percent had mild disease, whereas only 48 percent of the 187 unvaccinated children with chickenpox had mild disease (P<0.001). Among the 202 children with PCR-confirmed varicella-zoster virus and their 389 matched controls, 23 percent of the children with chickenpox and 61 percent of the matched controls had received the vaccine (vaccine effectiveness, 85 percent; 95 percent confidence interval, 78 to 90 percent; P<0.001). Against moderately severe and severe disease the vaccine was 97 percent effective (95 percent confidence interval, 93 to 99 percent). The effectiveness of the vaccine was virtually unchanged (87 percent) after adjustment for potential confounders by means of conditional logistic regression. CONCLUSIONS: Varicella vaccine is highly effective as used in clinical practice.

Publication Types:

  • Evaluation Studies

PMID: 11274621 [PubMed - indexed for MEDLINE]

AN: 21146520

Scand J Infect Dis 1998;30(1):17-21 Related Articles, Books, LinkOut
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Acute and long-term changes in T-lymphocyte subsets in response to clinical and subclinical measles. A community study from rural Senegal.

Lisse I, Samb B, Whittle H, Jensen H, Soumare M, Simondon F, Aaby P.

Department of Pathology, Hvidovre Hospital, Denmark.

To investigate the possibility of long-term suppression of T-lymphocyte subsets, we examined children exposed to measles at home during an epidemic in rural Senegal, at time of exposure and 1 and 6 months later. The measles case fatality ratio was 1%. Subclinical measles was common among vaccinated children exposed to measles (45%). Both clinical and subclinical cases of measles showed a significant rise in absolute CD4 count in the incubation period. In the prodromal phase and the first week after the rash, the lymphocyte percentage, the white blood cell count and the absolute CD4 cell numbers were significantly reduced. There was no persistent decrease of absolute CD4 or CD8 numbers at 1 or 6 months after exposure. Measles infection was followed by significant changes in the subset composition, both CD4 and CD8 percentages being significantly higher in the second month after measles than among non-seroresponders. These changes were more marked among girls, since they had significantly higher CD4 percentages and CD4/CD8 ratios than boys in the convalescence phase. In conclusion, measles infection is not associated with a long-term suppression of CD4+ or CD8+ T-lymphocytes.

PMID: 9670353 [PubMed - indexed for MEDLINE]

AN: 98335009

J Med Virol 1998 Sep;56(1):85-90 Related Articles, Books, LinkOut
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Estimated susceptibility to asymptomatic secondary immune response against measles in late convalescent and vaccinated persons.

Damien B, Huiss S, Schneider F, Muller CP.

Laboratoire National de Sante, Luxembourg, Germany.

Serological evidence indicates that measles virus (MV) could circulate in seropositive, fully protected populations. Among individuals fully protected against disease, those prone to asymptomatic secondary immune response are the most likely to support subclinical MV transmission. The serological characteristics of protected subjects who developed secondary immune response after reexposure to measles have been described recently [Huiss et al. (1997): Clinical and Experimental Immunology 109:416-420]. On the basis of these data, a threshold of susceptibility was defined to estimate frequencies of secondary immune response competence in different populations. Among measles, late convalescent adults (n = 277) and vaccinated high school children (n = 368), 3.2-3.9% and 22.2-33.2%, respectively, were considered susceptible to secondary immune response. A second vaccination did not seem to lower this incidence. Even when estimates of symptomatic secondary immune response (e.g., secondary vaccine failure) were taken into account, susceptibility to subclinical secondary immune response was still 5-8 times higher after vaccination than after natural infection. Although viral transmission between protected individuals has never been directly demonstrated, the data describe a population in which protected but infectious persons could potentially be of epidemiological importance.

PMID: 9700638 [PubMed - indexed for MEDLINE]

AN: 98365995

: J Infect 1997 May;34(3):273-6 Related Articles, Books, LinkOut

Subclinical rubella reinfection during pregnancy followed by transmission of virus to the fetus.

Aboudy Y, Fogel A, Barnea B, Mendelson E, Yosef L, Frank T, Shalev E.

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

We report a documented case of rubella reinfection during pregnancy in a previously vaccinated woman with residual antibody titre to rubella of 15 IU/ml. The reinfection occurred following an exposure to rubella virus (contact with 6-year-old daughter with clinical rubella) between the 7th and 10th week of pregnancy which resulted in transmission of the virus to the fetus. Umbilical cord blood drawn by cordocentesis was found to be strongly positive for rubella IgM antibody. After termination of the pregnancy rubella virus was isolated in cell culture from fetal tissues.

PMID: 9200039 [PubMed - indexed for MEDLINE]

AN: 97343483

: Pediatr Infect Dis J 1997 Apr;16(4 Suppl):S90-6 Related Articles, Books, LinkOut

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Comparative efficacy of acellular pertussis vaccines: an analysis of recent trials.

Cherry JD.

Department of Pediatrics, UCLA Children's Hospital, USA.

Diphtheria-tetanus-acellular pertussis vaccines have been licensed in the United States since 1991. Compared with the whole cell pertussis component diphtheria-tetanus-pertussis vaccine, the diphtheria-tetanus-acellular pertussis vaccines were found in reactogenicity and immunogenicity studies to be immunogenic with respect to their specific antigen content and to be associated with less severe and less frequent adverse reactions. A case definition of pertussis was developed by the World Health Organization for use in vaccine efficacy trials, but this definition eliminates some laboratory-confirmed cases from efficacy calculations. Because these cases are more common in vaccinees than in controls, vaccine efficacy appears better than it truly is whereas less effective vaccines seem comparable with their more effective counterparts. In addition observer bias may contribute to the appearance of enhanced efficacy of the less effective vaccines, which tend to prevent typical but not mild disease. When analyzing efficacy based on prevention of laboratory-confirmed pertussis with cough > or = 7 days, single component pertussis toxin (PT) toxoid vaccines were found to be less effective than two-component PT toxoid/filamentous hemagglutinin vaccines, and three- or four-component vaccines containing pertactin in addition to PT toxoid and filamentous hemagglutinin were more effective than either the single-component or two-component vaccines.

PMID: 9109163 [PubMed - indexed for MEDLINE]

AN: 97262955

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

Soz Praventivmed 1995;40(2):110-5 Related Articles, Books, LinkOut

[Mumps vaccines: vaccination failures from an immunological viewpoint]

[Article in German]

Hess U.

Bundesamt fur Gesundheitswesen, Bern.

The significance of mucosal and systemic immunity is illustrated with the example of the different immune response of Poliovaccine live oral (Sabin) and Poliovaccine inactivated parenteral (Salk). On the occasion of rubella- and measles-outbreaks it will be demonstrated that in vaccinated people subclinical reinfections may much more frequently occur than clinically manifest diseases. On the basis of these findings one may consider the large number of parotitis cases without complications in mumps vaccinated Swiss pupils as secondary mucosal vaccine failures at a time, when systemic immunity still was protective. Significance for vaccination policy and consequences for handling of vaccines shall be briefly discussed.

PMID: 7747520 [PubMed - indexed for MEDLINE]

AN: 95266359

J Egypt Public Health Assoc 1992;67(3-4):369-78 Related Articles, Books

Antibody level after measles vaccination.

Fathy MM, el-Khashaab TH, Darwish MA.

Department of Microbiology and Immunology, Faculty of Medicine, Ain Shams University, Cairo, Egypt.

The present study was designed to estimate the level of measles IgG antibody in infants early after vaccination and in preschool children to determine their immune status. Three groups were studied: Group I, unvaccinated infants, Group II, recently vaccinated infants and Group III vaccinated preschool children. Measles IgG antibody was measured using the ELISA technique. The study showed that 90% (18/20) of the unvaccinated Group I infants were seronegative and only 10% were seropositive for measles IgG antibody representing most probably persisting maternal antibodies. Fifty percent (15/30) of recently vaccinated Group II infants were seropositive. A statistically significant higher antibody level was observed in Group II infants in comparison to those of Group I. The majority of seropositive infants of Group II (10/15 = 66.7%) showed high antibody level representing successful vaccination. Seropositives represented 77.4% (24/31) of Group III preschool children and the majority of them 75% (18/24) showed high antibody level which was significantly higher than the comparable in Group II infants, most probably due to subclinical infection in addition to successful vaccination. Fifty percent (15/30) of Group II infants and 22.6% (7/31) of Group III children were seronegative, more likely due to failure of initial vaccination.

PMID: 1296968 [PubMed - indexed for MEDLINE]

AN: 93210423

: Pediatr Infect Dis J 1990 Oct;9(10):700-5 Related Articles, Books, LinkOut

Serologic evidence of subclinical pertussis in immunized children.

Long SS, Lischner HW, Deforest A, Clark JL.

Department of Pediatrics, St. Christopher's Hospital for Children, Philadelphia, PA 19134.

Incidental to a vaccine study involving 783 immunized children conducted at two study sites, inner city children had significantly higher geometric mean pertussis agglutinin titers compared with suburban children just before the fourth dose of diphtheria-tetanus-whole cell pertussis vaccine (47 vs. 25; P less than 0.001). Higher titers in the inner city were correlated with residence in census tracts where cases of pertussis were reported. Three hundred thirty-two children in a placebo arm of the study who were clinically observed and had paired serum samples taken during a 2- to 4-month period were analyzed for evidence of natural Bordetella infection. Twelve (11%) inner city children and three (1.3%) suburban children had spontaneous 4-fold or greater rises in at least two different pertussis antibodies measured (agglutinin, antitoxin or enzyme-linked immunosorbent assay for IgG to pertussis toxin, IgG and IgA to filamentous hemagglutinin). Eighty percent of these children had IgA to filamentous hemagglutinin. Nine of 12 inner city children with serologic evidence of pertussis lived within 6 blocks of a case of pertussis reported within 1 month of the observed antibody rise in study subjects; none had a household member with pertussis and none had symptomatic disease.

PMID: 2235142 [PubMed - indexed for MEDLINE]

AN: 91044636

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

Eur J Pediatr 1988 Feb;147(2):195-6 Related Articles, Books, LinkOut

Congenital rubella infection after previous immunity of the mother.

Saule H, Enders G, Zeller J, Bernsau U.

II. Kinderklinik im Krankenhauszweckverband, Augsburg, Federal Republic of Germany.

A newborn boy was admitted with a congenital rubella infection. Seven years previously his mother had been vaccinated against rubella; 3 years previously rubella immunity had been confirmed. Therefore, intrauterine transmission must have occurred after maternal reinfection during pregnancy. Prenatal diagnosis of rubella embryopathy with serological methods after subclinical maternal reinfection is nearly impossible.

PMID: 3366138 [PubMed - indexed for MEDLINE]

AN: 88211608

Trop Anim Health Prod 1987 Feb;19(1):47-52 Related Articles, Books, LinkOut

Challenge study on infectious bursal disease in chicks derived from vaccinated hens.

Abdu PA, Abdullahi SU, Adesiyun AA, Ezeokoli CD.

Presence and levels of maternal antibody (MA) in broiler chicks derived from hens vaccinated with a live infectious bursal disease (IBD) vaccine were investigated by a quantitative agar-gel precipitin test. At day old 100% of the chicks tested had MA; by 17 days of age it was present in only 10%. The mean MA level at day old was 337.5 UK units/ml but decreased to 6.3 UK units/ml at 17 days of age. Randomly selected chicks from the pool studied were challenged at weekly intervals from day old for 29 days with an IBD virus obtained from a natural outbreak. Subclinical and clinical disease were observed in chicks challenged at eight and 29 days of age respectively.

PMID: 3037742 [PubMed - indexed for MEDLINE]

AN: 87264849

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

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

Postgrad Med J 1985;61 Suppl 4:133-5 Related Articles, Books, LinkOut

Live varicella immunization in healthy non-immune nurses.

Ndumbe PM, Cradock-Watson JE, Heath RB, Levinsky RJ.

Thirty-four varicella-zoster virus (VZV) seronegative nurses were vaccinated with the live varicella vaccine (Varilrix) and followed for periods of up to 36 months. No major vaccine reactions were observed. At 5 and 12 months, 94% of the nurses had seroconverted but at 3 years, only 64% retained antibody activity. However, lymphocyte transformation to VZV antigen was positive in 7 seronegative nurses, all of whom had previously seroconverted. The one nurse who developed chickenpox had not seroconverted after vaccination. Two out of 11 seroconverted nurses had a subclinical reinfection, as shown by a rise in antibody, upon exposure to varicella. In contrast, 4 out of 5 seronegative nurses who had refused vaccination developed chickenpox. Varilrix is therefore safe, immunogenic, and protective in adults and can be considered for routine use in susceptible health workers. However, it is still uncertain whether lifelong immunity is obtained with this vaccine. Both cell-mediated and antibody tests are needed for long-term assessment of immunity to chickenpox.

PMID: 3014470 [PubMed - indexed for MEDLINE]

AN: 86259490

Lancet 1985 Feb 2;1(8423):244-6 Related Articles, Books, LinkOut

Detection of rubella-specific IgM in subclinical rubella reinfection in pregnancy.

Morgan-Capner P, Hodgson J, Hambling MH, Dulake C, Coleman TJ, Boswell PA, Watkins RP, Booth J, Stern H, Best JM, et al.

Seven cases of asymptomatic rubella reinfection in early pregnancy are described. In each, there was a history of exposure to a rubelliform illness and low levels of rubella-specific IgM subsequently appeared in the serum. Four of the women had been immunised, after having been shown to be susceptible to rubella, one had been immunised at school without previous antibody screening, and two were uncertain about immunisation. One pregnancy was terminated and rubella virus was not isolated from the products of conception. Six pregnancies went to term and the infants showed no evidence of intrauterine infection. In a further case it was impossible to discriminate between reinfection and primary infection, and termination of pregnancy was offered.

PMID: 2857319 [PubMed - indexed for MEDLINE]

AN: 85109993

Scand J Infect Dis 1985;17(4):337-41 Related Articles, Books, LinkOut

Subclinical rubella reinfection in vaccinated women with rubella-specific IgM response during pregnancy and transmission of virus to the fetus.

Forsgren M, Soren L.

This report concerns 2 cases of documented rubella reinfection during pregnancy in previously vaccinated women. The antibody response at reinfection comprised not only anti-rubella IgG but also IgM. In the first case the reinfection occurred between the 13th and 19th week of pregnancy and was followed by transmission of virus to the fetus (anti-rubella IgM in cord blood and persisting antibody activity). The child had no clinical signs of congenital rubella and is normally developed without hearing impairment at 41/2 years of age. In the second case the reinfection resulted from exposure in the 15th week of pregnancy; there were neither serological nor clinical signs of congenital rubella in the child. The reported case of fetal infection in spite of previous rubella vaccination of the mother does not discourage the use of rubella vaccine. Rubella vaccine induces long lasting immunity and protection from viremia in the vast majority of individuals.

PMID: 4089542 [PubMed - indexed for MEDLINE]

AN: 86122676

Med J Aust 1982 Jun 12;1(12):514-5 Related Articles, Books, LinkOut

Congenital rubella after successful vaccination.

Bott LM, Eizenberg DH.

We report a case of a patient who had a subclinical rubella infection in the first trimester of pregnancy which resulted in the delivery of a baby suffering from congenital rubella. Rubella virus vaccine, liver attenuated (Cendevax) vaccine had been administered to the mother nearly three years before, with proven seroconversion from a rubella haemagglutination-inhibition titre of 1:10 to 1:80.

PMID: 7099094 [PubMed - indexed for MEDLINE]

AN: 82245112

: JAMA 1978 Dec 8;240(24):2635-7 Related Articles, Books, LinkOut

Rubella-vaccinated students. Follow-up in a public school system.

Schiff GM, Rauh JL, Young B, Trimble S, Rotte T, Schiff BE.

In a 7 1/2-year follow-up evaluation of the duration of rubella-vaccine-induced immunity of students who received either HPV-77 DK-12 or Cendehill vaccine, both groups showed a continous decline in hemagglutination-inhibition antibody from seven weeks after vaccination but a lower decline between 4 1/2 and 7 1/2 years after vaccination. However, at 7 1/2 years only 16 students (8%) receiving the Cendehill vaccine and one student (0.5%) receiving the HPV-77 DK-12 vaccine lacked detectable antibody. Despite the persistence of antibody titers, there was evidence of subclinical rubella among both groups of vaccinated students. These results emphasize the importance of continued evaluation of the conditions of persons receiving rubella vaccine.

PMID: 712979 [PubMed - indexed for MEDLINE]

AN: 79050803

Biken J 1978 Mar;21(1):25-31 Related Articles, Books, LinkOut

Rubella epidemic in an institution: protective value of live rubella vaccine and serological behavior of vaccinated, revaccinated and naturally immune groups.

Baba K, Yabuuchi H, Okuni H, Harima R, Minekawa Y, Taniuchi M, Otsuka T, Takahashi M, Okuno Y.

A rubella epidemic occurred in an institutional population composed of 189 susceptible, 37 naturally immune, 35 previously vaccinated and 38 serologically uncharacterized children and nursing staff. The epidemic lasted 3.5 months and showed more than 5 waves. Detailed clinical and serological examinations of these subjects were made. A rash appeared in 156 (52%) of 299 persons, including 145 (87%) of 166 unvaccinated and serologically uncharacterized subjects, but not in the 72 immune persons. In the middle of the 3rd wave urgent vaccination of 61 children aged 0 to 2 years of the susceptible group reduced the rate of appearance of a rash to 11 of the children (18%), as compared with 126 (98%) of 128 subjects in the unvaccinated non-immune group. The epidemic only reached a 4th wave in the vaccinated group, but it extended to a 5th wave or more in unvaccinated subjects. None of the 35 subjects in a previously vaccinated group developed rubella, although the rate of subclinical reinfection in this previously vaccinated group was higher (35%) than that in the naturally immune group (17%). Three cases of subclinical reinfection were detected even among 6 previously revaccinated subjects.

PMID: 666723 [PubMed - indexed for MEDLINE]

AN: 78210426

JAMA 1978 Dec 8;240(24):2635-7 Related Articles, Books, LinkOut

Rubella-vaccinated students. Follow-up in a public school system.

Schiff GM, Rauh JL, Young B, Trimble S, Rotte T, Schiff BE.

In a 7 1/2-year follow-up evaluation of the duration of rubella-vaccine-induced immunity of students who received either HPV-77 DK-12 or Cendehill vaccine, both groups showed a continous decline in hemagglutination-inhibition antibody from seven weeks after vaccination but a lower decline between 4 1/2 and 7 1/2 years after vaccination. However, at 7 1/2 years only 16 students (8%) receiving the Cendehill vaccine and one student (0.5%) receiving the HPV-77 DK-12 vaccine lacked detectable antibody. Despite the persistence of antibody titers, there was evidence of subclinical rubella among both groups of vaccinated students. These results emphasize the importance of continued evaluation of the conditions of persons receiving rubella vaccine.

PMID: 712979 [PubMed - indexed for MEDLINE]

AN: 79050803

: Pediatrics 1975 Sep;56(3):380-7 Books, LinkOut

Long-term follow-up for immunity after monovalent or combined live measles, mumps, and rubella virus vaccines.

Weibel RE, Buynak EB, McLean AA, Hilleman MR.

Antibody in human subjects persisted without substantial decline for 8 years after mumps vaccine (Jeryl Lynn), for 6 years after measles (Attenuvax), for 5 1/2 years after rubella vaccine (HPV-77 duck), for 5 years after measles-mumps-rubella and mumps-rubella combined vaccines, for 4 years after measles and rubella, and for 2 years after measles-mumps vaccines, the longest periods tested. Protective immunity against mumps illness persisted through the eighth year. The patterns for antibody following vaccination parallel those for natural infection and indicate that immunity will be lasting. Subclinical reinfection evidenced by antibody increase was commonly seen in persons who had been vaccinated, much as follows the natural infection.

PMID: 1161394 [PubMed - indexed for MEDLINE]

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