A combined measles,mumps, rubella and varicella vaccine (Priorix-Tetra™): Immunogenicity and safety profile

Priorix-Tetra™ (GlaxoSmithKline Biologicals) is a combined measles, mumps, rubella and varicella (MMRV) vaccine. Eight studies involving more than 3000 children were reviewed. Compared with co-administration of MMR (Priorix™) and varicella (Varilrix™) vaccines, the MMRV vaccine showed: similar immunogenicity, with immunity shown up to 3 years post-vaccination; a higher rate of fever after the first dose; a slight increase in mild local reactions after the second dose. This MMRV vaccine can be used either as a two-dose vaccine or as a second dose in children primed with separate MMR and/or varicella vaccines, offering a convenient way to introduce varicella vaccination into routine vaccination programmes.     

Immunogenicity and safety of measles-mumps-rubella-varicella (MMRV) vaccine followed by one dose of varicella vaccine in children aged 15 months–2 years or 2–6 years primed with measles-mumps-rubella (MMR) vaccine

In this open, randomized, comparative study (105908/NCT00353288), 458 age-stratified children (15 months–2 years and 2–6 years) previously primed with MMR received one dose of either a combined MMRV vaccine (Priorix-Tetra™, MMRV group) or concomitant MMR and varicella vaccines (Priorix™ and Varilrix™, MMR + V group), followed 42–56 days later by another dose of varicella vaccine (Varilrix™) in both groups. Post-vaccination measles, mumps and rubella seropositivity rates and antibody geometric mean titers (GMTs) were high (99.5% for anti-measles and 100% for anti-mumps and anti-rubella) in both vaccine groups. In the two age strata, varicella seroconversion rates were, post-dose 1: ≥97.6% (MMRV), ≥96.6% (MMR + V) and, post-dose 2: 100% in both groups. Post-dose 2, anti-varicella GMTs increased respectively 14.1- and 12.6-fold (MMRV), and 9.8- and 13.1-fold (MMR + V). Both vaccine regimens were well-tolerated. Post-dose 1, the incidence of any solicited local symptom during the 4-days follow-up was ≤28.2% (MMRV) and ≤19.8% (MMR + V) and the incidence of fever >39.5 °C (rectal temperature) within 15 days was ≤2.8% (MMRV) and ≤2.6% (MMR + V). This MMRV vaccine appears an immunogenic and safe substitute for a second dose of MMR vaccine in young children. The increase in anti-varicella antibodies observed after a second dose of varicella vaccine supports a two-dose schedule for varicella-containing vaccine.     

Rubella virus neutralizing antibody response after a third dose of measles-mumps-rubella vaccine in young adults

BackgroundThird doses of measles-mumps-rubella (MMR) vaccine have been administered during mumps outbreaks and in various non-outbreak settings. The immunogenicity of the rubella component has not been evaluated following receipt of a third dose of MMR vaccine.MethodsYoung adults aged 18–31 years with documented two doses of MMR vaccine received a third dose of MMR vaccine between July 2009 and October 2010. Rubella neutralizing antibody titers were assessed before, 1 month, and 1 year after receipt of a third dose of MMR vaccine.ResultsAmong 679 participants, 1.8% had rubella antibody titers less than 10 U/ml, immediately before vaccination, approximately 15 years after receipt of a second dose of MMR vaccine. One month after receipt of a third dose of MMR vaccine, average titers were 4.5 times higher and >50% of participants had a 4-fold boost. Response was highest among those with titers less than 10 U/ml prior to vaccination (geometric mean titer ratio = 18.8; 92% seroconversion) and decreased with increasing pre-vaccination titers. Average titers declined 1 year postvaccination but remained significantly higher than pre-vaccination levels. The proportion classified as low-positive antibody levels increased from 3% 1 month postvaccination to 24% 1 year postvaccination.ConclusionsVaccination with a third dose of MMR vaccine resulted in a robust boosting of rubella neutralizing antibody response that remained elevated 1 year later. Young adults with low rubella titers are more likely to benefit from a third dose of MMR vaccine.     

Seroprevalence of Antibodies to Measles, Mumps, and Rubella among Thai Population: Evaluation of Measles/MMR Immunization Programme

Stored serum specimens, from four regions of Thailand, of healthy children attending well baby clinics and of healthy people with acute illnesses visiting outpatient clinics were randomly sampled and tested for IgG antibody to measles, mumps, and rubella (MMR). The immunity patterns of rubella and mumps fitted well with the history of rubella and MMR vaccination, seroprotective rates being over 85% among those aged over seven years. A high proportion of younger children acquired the infection before the age of vaccination. MMR vaccination should preferably be given to children at an earlier age. For measles, 73% seroprotective rates among children, aged 8-14 years, who should have received two doses of measles/MMR vaccine, were lower than expected. This finding was consistent with the age-group reported in outbreaks of measles in Thailand. The apparent ineffectiveness (in relation to measles) of MMR immunization of 1^st grade students warrants further studies.Key words: Antibodies, Immunization, Measles, Measles vaccine, Mumps, MMR vaccine, Rubella, Seroepidemiologic studies, Seroprevalence, Vaccination, Thailand     

Measles,mumps, and rubella antibody patterns of persistence and rate of decline following the second dose of the MMR vaccine

BackgroundAntibodies to measles, mumps, and rubella decline 3% per year on average, and have a high degree of individual variation. Yet, individual variations and differences across antigens are not well understood. To better understand potential implications on individual and population susceptibility, we reanalyzed longitudinal data to identify patterns of seropositivity and persistence.MethodsChildren vaccinated with the second dose of measles, mumps, rubella vaccine (MMR2) at 4–6 years of age were followed up to 12 years post-vaccination. The rates of antibody decline were assessed using regression models, accounting for differences between and within subjects.ResultsMost of the 302 participants were seropositive throughout follow-up (96% measles, 88% mumps, 79% rubella). The rate of antibody decline was associated with MMR2 response and baseline titer for measles and age at first dose of MMR (MMR1) for rubella. No demographic or clinical factors were associated with mumps rate of decline. One month post-MMR2, geometric mean titer (GMT) to measles was high (3892 mIU/mL), but declined on average 9.7% per year among those with the same baseline titer and <2-fold increase post-MMR2. Subjects with ≥2-fold experienced a slower decline (≤7.4%). GMT to rubella was 149 one month post-MMR2, declining 2.6% and 5.9% per year among those who received MMR1 at 12–15 months and >15 months, respectively. GMT to mumps one month post-MMR2 was 151, declining 9.2% per year. Only 14% of subjects had the same persistence trends for all antigens.ConclusionsThe rate of antibody decay varied substantially among individuals and the 3 antigen groups. A fast rate of decline coupled with high variation was observed for mumps, yet no predictors were identified. Future research should focus on better understanding waning titers to mumps and its impacts on community protection and individual susceptibility, in light of recent outbreaks in vaccinated populations.     

Antibody persistence in children aged 6–7 years one year following booster immunization with two MMR vaccines applied by aerosol or by injection

ImportanceIn a previous study on booster vaccination, we reported that two aerosolized MMR vaccines were as safe and immunogenic as injectable vaccines containing the same antigens. We now present results of antibody persistence one year after immunization.ObjectiveTo assess the antibody persistence for measles, mumps, and rubella one year following booster immunization.MethodsWe performed clinical and serological follow-up of participants in a previous study of Mexican children aged 6–7 years, in which participants were randomized to four groups receiving, by aerosolized or by injection, the MMR SII vaccine (Serum Institute of India), or the MMR II (Merck Sharp & Dhome). We evaluated the antibody persistence by PRN test for measles and by ELISA for rubella and mumps. The occurrence of clinical events was evaluated via periodic visits of a nurse team to children’s schools and homes.ResultsOf the 260 initial participants, 241 completed one-year follow-up. There were only statistically significant differences in baseline seropositivity for mumps. One year after immunization, seropositivity in all groups was 100% for measles and rubella. The seropositivity rank for mumps was from 90.3% for the injected vaccine MMR II to 96.6% for vaccine MMR SII applied by aerosol; these differences were not statistically significant. With exception of the aerosolized vaccine MMR SII for the geometric mean titer (GMT) for measles, all study groups presented declination of GMT for the three viruses. The difference between the aerosolized vaccines MMR SII and MMR RII was statistically significant for mumps antibodies. Only mild clinical events were identified.ConclusionUnder conditions of no endemic transmission for measles and rubella, and of low circulation of mumps virus, school-aged children remained seropositive to the three viruses one year following booster immunization.The study was registered under CMN 2010-005 number at COFEPRIS (National Regulatory Authority).     

Mutual interference on the immune response to yellow fever vaccine and a combined vaccine against measles, mumps and rubella

A randomized trial was conducted to assess the immunogenicity and reactogenicity of yellow fever vaccines (YFV) given either simultaneously in separate injections, or 30 days or more after a combined measles-mumps-rubella (MMR) vaccine. Volunteers were also randomized to YFV produced from 17DD and WHO-17D-213 substrains. The study group comprised 1769 healthy 12-month-old children brought to health care centers in Brasilia for routine vaccination. The reactogenicity was of the type and frequency expected for the vaccines and no severe adverse event was associated to either vaccine. Seroconversion and seropositivity 30 days or more after vaccination against yellow fever was similar across groups defined by YFV substrain. Subjects injected YFV and MMR simultaneously had lower seroconversion rates - 90% for rubella, 70% for yellow fever and 61% for mumps - compared with those vaccinated 30 days apart - 97% for rubella, 87% for yellow fever and 71% for mumps. Seroconversion rates for measles were higher than 98% in both comparison groups. Geometric mean titers for rubella and for yellow fever were approximately three times higher among those who got the vaccines 30 days apart. For measles and mumps antibodies GMTs were similar across groups. MMR's interference in immune response of YFV and YFV's interference in immune response of rubella and mumps components of MMR had never been reported before but are consistent with previous observations from other live vaccines. These results may affect the recommendations regarding primary vaccination with yellow fever vaccine and MMR.     

Safety and immunogenicity of a measles–mumps–rubella–varicella vaccine given as a second dose in children up to six years of age

Two doses of measles–mumps–rubella vaccine (MMR) are widely recommended and consideration is being given to a similar schedule for varicella vaccine. A combined measles–mumps–rubella–varicella vaccine (MMRV) could be considered for this second dose in children previously vaccinated separately with MMR and varicella vaccines. Healthy children (N = 390) aged 15–75 months (median 54 months) previously immunized with MMR and varicella vaccines were randomly allocated to receive MMRV or separate injections of MMR and varicella vaccines. Before administration of study vaccines, seropositivity rates were 96.4% for measles, 94.3% for mumps, 99.5% for rubella, and 97.9% for varicella. Post-immunization, seropositivity rates were 99.5% for measles and mumps and 100% for rubella and varicella in the MMR + varicella group and 100% for all four antigens in the MMRV group; a 26.2- and 27.2-fold increase in varicella titer was observed in the MMR + varicella vaccine and MMRV groups, respectively. Except for more frequent pain in the MMRV group (33.3% vs. 23.7%, p = 0.043), there were no differences in the incidence of local and solicited symptoms between groups. In children primed with MMR and varicella vaccine, MMRV had non-inferior immunogenicity and similar safety profiles as a second dose of licensed MMR and varicella vaccine administered concomitantly.     

Seroprevalence of measles, mumps and rubella antibodies in Luxembourg: results from a national cross-sectional study

A serological prevalence survey was carried out in Luxembourg during 2000-2001 to determine the antibody status of the Luxembourg population against vaccine-preventable infections. Blood samples of children and adolescents were collected prospectively in randomly selected schools. Samples of adults were obtained through volunteer patients of the national health laboratory or of the mandatory pre-nuptial test. Measles, mumps and rubella (MMR) virus antibody concentrations were measured using commercial ELISA tests. Age-standardized prevalence of measles, mumps and rubella virus antibodies was found to be 96.58, 75.40 and 95.69% respectively. Significant age-dependence of serology was observed for all three infections, with study participants born after the introduction of the MMR vaccine experiencing a gradual decline of antibodies following vaccination in childhood. Older study participants who were more likely to have antibodies from natural infection had consistently higher titres than younger individuals. Present vaccination coverage with MMR appears to be sufficient to prevent large local outbreaks of measles and rubella, but probably not mumps.     

Immunogenicity of second dose measles-mumps-rubella (MMR) vaccine and implications for serosurveillance.

Measles and mumps, but not rubella, outbreaks have been reported amongst populations highly vaccinated with a single dose of measles-mumps-rubella (MMR) vaccine. Repeated experience has shown that a two-dose regime of measles vaccine is required to eliminate measles. This paper reports the effect of the first and second MMR doses on specific antibody levels in a variety of populations.2-4 years after receiving a first dose of MMR vaccine at age 12-18 months, it was found that a large proportion of pre-school children had measles (19.5%) and mumps (23.4%) IgG antibody below the putative level of protection. Only a small proportion (4.6%) had rubella antibody below the putative protective level. A total of 41% had negative or equivocal levels to one or more antigens. The proportion measles antibody negative (but not rubella or mumps) was significantly higher in children vaccinated at 12 months of age than at 13-17 months. There was no evidence for correlation of seropositivity to each antigen, other than that produced by a small excess of children (1%) negative to all three antigens. After a second dose of MMR, the proportion negative to one or more antigens dropped to <4%. Examination of national serosurveillance data, found that following an MR vaccine campaign in cohorts that previously received MMR, both measles and rubella antibody levels were initially boosted but declined to pre-vaccination levels within 3 years.Our study supports the policy of administering a second dose of MMR vaccine to all children. However, continued monitoring of long-term population protection will be required and this study suggests that in highly vaccinated populations, total measles (and rubella) IgG antibody levels may not be an accurate reflection of protection. Further studies including qualitative measures, such as avidity, in different populations are merited and may contribute to the understanding of MMR population protection.     

The control of mumps in Israel

Background: Measles–mumps–rubella (MMR) vaccine replaced monovalent measles vaccine in the routine childhood vaccination schedule in Israel in December 1988, primarily to achieve the elimination of the congenital rubella syndrome. In this observational study, we report on changes in reported mumps incidence in Israel from the time of the introduction of MMR vaccine until the end of 1998. Methods: The report is based upon passive national surveillance of mumps incidence, which has been notifiable in Israel since 1977. Results: Reported mumps incidence in Israel is now less than 2% the pre-vaccine incidence. Conclusions: In the decade since the introduction of routine mumps vaccination in 1-year-olds in Israel, mumps control has been achieved. Although small outbreaks occur and may continue to occur in future years, because of undervaccination of children, primary vaccine failure and waning immunity, it can tentatively be said that mumps is no longer a public health problem in Israel.     

Rubella virus-specific humoral immune responses and their interrelationships before and after a third dose of measles-mumps-rubella vaccine in women of childbearing age

In the U.S., measles, mumps, and rubella vaccination is recommended as two vaccine doses. A third dose of measles-mumps-rubella (MMR) vaccine is being administered in certain situations (e.g., identified seronegativity and during outbreaks).We studied rubella-specific humoral immunity (neutralizing antibody, enzyme-linked immunosorbent assay/ELISA IgG titer and antibody avidity) and the frequencies of antigen-specific memory B cells before and after a third dose of MMR-II in 109 female participants of childbearing age (median age, 34.5 years old) from Olmsted County, MN, with two documented prior MMR vaccine doses. The participants were selected from a cohort of 1117 individuals if they represented the high and the low ends of the rubella-specific antibody response spectrum. Of the 109 participants, we identified four individuals (3.67% of all study participants; 7.14% of the low-responder group) that were seronegative at Baseline (rubella-specific ELISA IgG titers <10 IU/mL), suggesting a lack of protection against rubella before receipt of a third MMR vaccine dose. The peak geometric mean neutralizing antibody titer one month following the third dose of MMR vaccine for the cohort was 243 NT₅₀ (CI; 241, 245), which is expected for a cohort with two doses of MMR, and the peak geometric mean IgG titer was 150 IU/mL (CI; 148, 152) with no seronegative individuals at Day 28. One-third of all subjects (31.8% for the neutralizing antibody; 30.8% for the IgG titer) experienced a significant boost (≥4-fold) of antibody titers one month following vaccination. Antibody titers and other tested immune-response variables were significantly higher in the high-responder group compared to the low-responder group. The frequencies of rubella-specific memory B cells were modestly associated with the antibody titers. Our study suggests the importance of yet unknown inherent biologic and immune factors for the generation and maintenance of rubella-vaccine-induced humoral immune responses.     

Comparative analysis of the complete nucleotide sequences of measles,mumps, and rubella strain genomes contained in Priorix-Tetra™ and ProQuad™ live attenuated combined vaccines

Measles, mumps, and rubella are three common viral childhood diseases that can have serious complications. Active immunization against these diseases became possible with the development of live attenuated virus vaccines in the late 1960s. Vaccines against these three diseases were combined into trivalent (Priorix™, GlaxoSmithKline Biologicals and M-M-R_II™, Merck & Co., Inc.) or tetravalent vaccines including the addition of a live attenuated VZV Oka strain (Priorix-Tetra™, GlaxoSmithKline Biologicals and ProQuad™, Merck & Co., Inc.). In this study, we report the complete nucleotide sequence of the vaccine strain genomes of the measles (Schwarz and attenuated Edmonston Enders), mumps (RIT 4385 and JL1 component of Jeryl Lynn), and rubella (Wistar RA 27/3) viruses included in the two tetravalent vaccines. Sequencing analysis of the individual virus components in the commercially distributed tetravalent vaccine lots showed that there are no nucleotide differences between the measles, mumps (JL1 component), and rubella vaccine strain genomes of Priorix-Tetra™ and ProQuad™. The observed genetic identity of the individual strains in both vaccines is consistent with their clinical profiles; Priorix-Tetra™ and ProQuad™ are both well tolerated and elicit protective immune responses against these three childhood diseases.     

Predicting and comparing long-term measles antibody profiles of different immunization policies

OBJECTIVE: Measles outbreaks are infrequent and localized in areas with high coverage of measles vaccine. The need is to assess long-term effectiveness of coverage. Since 1991, no measles epidemic affecting the whole island has occurred in Taiwan, China. Epidemiological models are developed to predict the long-term measles antibody profiles and compare the merits of different immunization policies on the island. METHODS: The current measles immunization policy in Taiwan, China, is 1 dose of measles vaccine at 9 months of age and 1 dose of measles, mumps and rubella (MMR) vaccine at 15 months of age, plus a 'mop-up' of MMR-unvaccinated schoolchildren at 6 years of age. Refinements involve a change to a two-dose strategy. Five scenarios based on different vaccination strategies are compared. The models are analysed using Microsoft Excel. FINDINGS: First, making the assumption that measles vaccine-induced immunity will not wane, the predicted measles IgG seroprevalences in preschool children range from 81% (lower bound) to 94% (upper bound) and in schoolchildren reach 97-98% in all strategy scenarios. Results are dependent on the association of vaccine coverage between the first and second dose of vaccine. Second, if it is assumed that vaccine-induced antibody titres decay, the long-term measles seroprevalence will depend on the initial titres post vaccination, decay rates of antibody titres and cut-off of seropositivity. CONCLUSION: If MMR coverage at 12 months of age can reach > 90%, it would be worth changing the current policy to 2 doses at 12 months and 6 years of age to induce higher antibody titres. These epidemiological models could be applied wherever a similar stage of measles elimination has been reached.     

Present anti-measles immunity in Jordan.

The immunity of adults and the prevalence of measles was determined in order to evaluate the adequacy of current measles vaccination policy in Jordan. A total of 307 sera, collected from adults aged 18--40 years, were tested for anti-measles antibodies by ELISA technique. The overall prevalence of anti-measles antibodies was 94.8% and there was no significant difference in the seropositivity rate between males (95.7%) and females (94%). Of the tested adults, 71% were vaccinated and 29% escaped vaccination. In Jordan, measles outbreaks occur periodically and predominantly attack children aged 5--14 years. Our data support introducing the compulsory MMR vaccine in the year 2000 to improve the vaccination coverage of measles; since the optional single dose vaccination has not interrupted the circulation of the measles virus. A second dose of MMR vaccine could be offered to Jordanians either at school entry or at the age of 11--12 years, based on the outcome of the compulsory single dose of MMR vaccine.     

Mumps,measles and rubella vaccination in children with PFAPA syndrome

There is no published data regarding immunologic response to vaccinations in children with PFAPA syndrome (periodic fever, aphthous stomatitis, pharyngitis and cervical adenitis). The aim of this study was to evaluate mumps, measles and rubella immunity in children with PFAPA. 31 children with PFAPA syndrome and 22 healthy children (control group – CG) were recruited to the study. All children were previously vaccinated with one dose of MMR vaccine according to the Polish obligatory vaccination schedule. The patients from both groups were evaluated for anti-measles, anti-mumps and anti-rubella IgG antibodies concentrations (ELISA tests; the reference values for protective antibody levels were 150 IU/L, 16 RU/L and 11 IU/ml respectively). The percentage of patients with protective antibodies levels was as follows: measles – 93.55% of PFAPA and 95.45% of CG patients (p = 0.77); mumps – 74.19% of PFAPA and 95.45% of CG patients (p = 0.02); rubella – 80.65% of PFAPA and 90.9% of CG patients (p = 0.30). Conclusions: Children with PFAPA syndrome present a good response to the measles and rubella component of the MMR vaccine, however immunity against mumps after one dose of MMR may not be sufficient. Further investigation concerning immunity against vaccine-preventable diseases and the safety of vaccinations in children with periodic fever syndromes is required.     

Antibody persistence in young adults 1 year after MMR immunization by aerosol or by subcutaneous route

Information on antibody persistence after aerosol revaccination with MMR components is limited. Thus, antibody titers were determined in 283 adult participants in a MMR vaccine trial 12 months after revaccination. One group had received aerosolized Triviraten vaccine while two other groups received either injected Triviraten or MMR II vaccine. Both MMR vaccines contained the same rubella strain, but different measles and mumps strains. Seropositivity to measles persisted in 98% of aerosolized vaccine recipients, 92% of injected Triviraten, and 95% of injected MMR II. All participants in the three groups retained seropositivity to rubella, while less than 50% remained seropositive to mumps.     

Immune non-interference and safety study of Vi-DT typhoid conjugate vaccine with a measles,mumps and rubella containing vaccine in 9–15 months old Nepalese infants

BackgroundTyphoid fever is a common disease in developing countries especially in the Indian subcontinent and Africa. The available typhoid conjugate vaccines (TCV) have been found to be highly immunogenic in infants and children less than 2 years of age. Many countries are planning to adopt TCV in their routine EPI programs around 9 months of age when measles containing vaccines are given. Therefore, Vi-DT TCV was tested in 9–15 months aged healthy infants in Nepal to demonstrate non-interference with a measles containing vaccine.MethodsThis was a randomized, open label, phase III study to assess the immune non-interference, safety, and reactogenicity of Vi-DT typhoid conjugate vaccine when given concomitantly with measles, mumps and rubella (MMR) vaccine. A total of 360 participants aged 9–15 months were enrolled and randomized equally into Vi-DT + MMR (180 participants) or MMR alone (180 participants) group and were evaluated for immunogenicity and safety 28 days post vaccination.ResultsUsing the immunogenicity set, difference between proportions (95% CI) of the Vi-DT + MMR group vs MMR alone group were ?2.73% (-8.85, 3.38), ?3.19% (-11.25, 4.88) and 2.91% (-3.36, 9.18) for sero-positivity rate of anti-measles, anti-mumps and anti- rubella, respectively. Only the lower bound of the range in difference of the proportions for sero-positivity rate of anti-mumps did not satisfy the non-inferiority criteria as it was above the ?10% limit, which may not be of clinical significance. These results were confirmed in the per protocol set. There were no safety concerns reported from the study and both Vi-DT + MMR and MMR alone groups were comparable in terms of solicited and unsolicited adverse events .ConclusionsResults indicated that there is non-interference of MMR vaccine with Vi-DT and Vi-DT conjugate vaccine could be considered as an addition to the EPI schedule among children at risk of contracting typhoid.     

Antibodies to measles,mumps, and rubella virus in Thai children after two-dose vaccination at 9 months and 2.5 years: A longitudinal study

IntroductionThailand changed the schedule of childhood measles–mumps–rubella (MMR) vaccination in 2014, moving the second dose from the age of 6 years to 2.5 years. There are currently no data on antibody responses to the MMR vaccine since this recommendation.Material and methodsWe investigated antibody responses in a cohort of children who received two doses of MMR vaccine at the ages of 9 months and 2.5 years that was originally established to evaluate antibody levels to Bordetella pertussis antigens (ClinicalTrials.gov no. NCT02408926). Infants were born to mothers who previously received tetanus–diphtheria–acellular pertussis vaccine at 27–36 weeks of gestation. Anti-measles, -mumps, and -rubella virus IgG levels were measured at birth (cord blood) and the ages of 2 and 7 months (before the first MMR vaccination); 18 and 24 months (9 and 15 months, respectively, after the first dose); and 36 months (6 months after the second dose) using commercially available enzyme-linked immunosorbent assay kits.ResultsAt 7 months of age, 96.2%, 99.6%, and 98.8% of infants had no protection against measles, mumps, and rubella, respectively. Levels of antibody against all three antigens increased significantly after the first but not the second dose. At 6 months after two-dose vaccination, 97.4%, 84.8%, and 78.7% of children remained seroprotected against measles, mumps, and rubella, respectively.ConclusionsMaternally derived antibodies to measles, mumps, and rubella virus disappeared by the age of 7 months in Thai children. Two-dose MMR vaccination at 9 months and 2.5 years of age induced robust immune responses against these viruses.