Second Dose Of MMR Research Articles

Catch-up vaccination campaign in children between 6 and 8 years old during COVID-19 pandemic: The experience in a COVID hub in Milan, Italy

BackgroundCOVID-19 has led to disruption in routine immunization programs around the world. Effective strategies need to be developed to address the decline in vaccine coverage to avoid preventable disease outbreaks. Our study reports a 4-days campaign for the catching-up of missed vaccinations in children aged between 6 and 8 years, in Milan, Italy. MethodsThe catch-up vaccination campaign (21st-24th of September 2021) involved children born in 2013, 2014 and 2015. These cohorts, if not already immunized, received the fourth dose of the Diphtheria-Tetanus-acellular Pertussis and Poliomyelitis vaccination (DTaPP4), the second dose of the Measles-Mumps and Rubella vaccination (MMR2) and Chickenpox, according to the Italian vaccine schedule. Results3,943 letters were sent to children with a missing vaccination. 1,315 children, 33% of expected, were vaccinated during the campaign. The 2015 cohort was the one that benefited most from the initiative, 955 children were vaccinated for a total of 1,864 doses administered. This has led to a significant increase of 20.0 percentage points (p.p.) in vaccination coverages for the fourth dose of DTaPP and the second dose of MMR. 214 children for the 2014 cohort and 146 for the 2013 cohort were vaccinated during the following days, these cohorts have been already called previously therefore the participation in the campaign and consequently the increase in vaccination coverages were less substantial. ConclusionsThis experience has demonstrated that a mass vaccination campaign could be a useful tool in catch-up strategies, even during the pandemic. It should be part of a bigger immunization program strategy that also includes efforts to simultaneously strengthen routine immunization services. With the appropriate organizational improvements, this initiative could pave the way for future successful campaigns involving different age groups and vaccinations.

Waning immunity and potential asymptomatic infection in 3–7 years old children who received one dose of measles-mumps-rubella vaccine: A 4-year prospective study

BackgroundMumps outbreaks in adolescents who received two doses of measles-mumps-rubella vaccine (MMR) during childhood have been reported worldwide. In China, one dose of MMR administered in children aged among 18–24 months has a limited effect on the mumps epidemic. There are limited prospective studies evaluating the mumps immunity profile of children aged 3–7 years who received one dose of MMR. This study aimed to describe mumps immunity profile over a span of 4-years in kindergarten and primary school children. MethodsAn observational, prospective study on one-dose MMR in children aged 3–7 years who underwent blood sample collection in 2015, 2016, and 2018 was conducted from 2015 to 2018. The seropositivity and geometric mean concentration of mumps IgG antibodies over time were analyzed. ResultsA total of 3346 eligible children aged 3–7 years who underwent three rounds of blood sample collection were included. The overall seropositivity (79.6%) in 2015 was significantly higher than those recorded in 2016 (73.1%) and 2018 (71.4%). Approximately 11.6–15.9% of the participants were seropositive for mumps in 2015, and converted to negative in 2016. Meanwhile, 11.1–14.6% of the participants were seropositive for mumps in 2016, and the results converted to negative in 2018. Over 6.1–7.4% of the participants had asymptomatic infection from 2015 to 2016, while 9.0–9.9% of the participants were infected without clinical symptoms from 2016 to 2018. ConclusionsKindergarten and primary school children who only received one dose of MMR were at higher risk of developing mumps. Waning immunity, seronegative conversion, and asymptomatic infection coexist in children who received one dose MMR. Determining the optimal age for administering the second dose of MMR in children should be prioritized to improve the control and prevention of mumps in China.

Eliminating measles: contributions by the Oporto international vaccination centre from 2017 to 2018

Abstract Background Measles is one of world's most contagious diseases and a growing population mobility has promoted its spreading. Outbreaks have been recorded around the world, despite public health efforts. Measles spreads faster among clusters of unvaccinated people. In 2018, World Health Organization reported 328629 cases worldwide, of which 82596 in Europe and 171 in Portugal- 93% of the latter were imported. Portugal had one of the highest proportions of childhood immunization coverage for Measles-Mumps-Rubella (MMR): 98% for first dose, and 96-98% for second. The main goal of this study was to describe the contribution of the Oporto International Vaccination Centre (OIVC), one of the largest in Portugal, to measles elimination. Methods Cross-sectional study, with analysis of vaccination records from travelers vaccinated for MMR at OIVC between January 2017 and December 2018. Results OIVC held 5426 pre-travel consultations in 2017, and 6192 in 2018. 535 travelers got the MMR vaccine (57.2% males). Mean age was 44.3±10.9 [1;76] years. Among travelers aged 12 months-18 years (n = 10), 50% were inoculated with the first dose and 50% with the second. Regarding adult travelers (n = 525), 71.6% received the first dose; 24.2% the second; 2.9% the third dose; and 1.3% received both first and second (within > 4 weeks). Conclusions The substantial number of inoculated vaccines in OIVC resulted from checking traveler's vaccination immunity status in all pre-travel consultations; this routine practice aimed at reducing the risk of importing/exporting measles. The second dose of MMR was justified by the diversity of travelers who came to OIVC, and to whom such inoculation was indicated: health professionals, humanitarian travelers, and workers in airlines and cruises. The third dose was given due to loss of measles serologic immunity. These measures are important to implement the recommendations of the Measles National Elimination Program, while contributing to global public health. Key messages This is an original study on the contribution of international vaccination centers to reduce the number of imported/exported cases and to eliminate measles - which is a global public health issue. At a global level, measles has a large disease burden. Therefore, it is essential to take every opportunity, including pre-travel consultations, to vaccinate people.

Seroprevalence and Determinants Associated with Mumps Antibodies after 20 Years of MMR Vaccination in Urban Area of Shanghai, China.

A resurgence of the mumps epidemic in highly vaccinated populations has occurred in recent years in many countries. This study aimed to evaluate the seroprevalence to mumps in urban areas of Shanghai, where a measles-mumps-rubella (MMR) vaccination had been implemented for 20 years. Mumps IgG antibodies were tested in 2662 residual sera from all ages in an urban area of Shanghai. A linear regression method was performed to assess the persistence of mumps antibodies after MMR vaccination. A logistic regression method was used to analyze the variables associated with seronegative sera. The overall age- and gender-adjusted seroprevalence of mumps antibodies reached 90% (95% CI: 90.0–90.2). The antibody concentration declined significantly in the first eight years after the second dose of MMR. The multivariate analysis identified that males, age groups, especially 17–19 years and no dose of vaccination, as well as one dose of vaccination, as factors associated with an increased risk of seronegative sera. A high seroprevalence to mumps has been achieved in the urban areas of Shanghai. A declining antibody level of mumps after the second dose of MMR may put a potential risk of recurrence of mumps. The two-dose MMR vaccine schedule is superior to one-dose schedule for mumps control.

Waning immunity of one-dose measles-mumps-rubella vaccine to mumps in children from kindergarten to early school age: a prospective study

ABSTRACTBackground: In China, one dose measles-mumps-rubella vaccine (MMR) was administered to children aged 18–24 months. The mumps incidence was still high. Data on the waning immunity to mumps after MMR vaccination are limited. This study aimed to describe the waning immunity to mumps in kindergarten and primary school children to provide a scientific basis for confirming an optimal age for a second dose.Methods: An observational, prospective study on one-dose MMR in children in kindergarten and primary school was conducted from 2015 to 2016. Waning immunity to mumps in terms of seropositivity and geometric antibody concentration (GMC) with time was analyzed.Results: In total, 7436 eligible subjects in kindergarten (3435) and primary school (4001) were included in 2015. The overall GMC (201.7 U/ml) and seropositivity (75.4%) to mumps antibodies in 2016 were significantly lower compared to those in 2015 (218.7 U/ml, 78.4%). Asymptomatic infection occurred within one year in 8.8% of children who received one-dose MMR.Conclusions: Children who received one-dose MMR in kindergarten and primary school were at high risk of mumps infection, and waning immunity occurred with time. Determining the optimal age for the second dose of MMR in children should be prioritized to prevent mumps epidemics.

La simplification du calendrier vaccinal est-elle appliquée ? Bilan 2 ans après sa mise en place

Study conducted on Internet among a representative sample of mothers reporting their child's vaccination record. The removal of the dose of DTPa-Hib at the age of 3months was quickly adopted since only 1% of children aged 6months had received three doses of DTPa in 2014compared to 96% in 2012. The booster dose is administered earlier for the DTPa and hepatitis B components. The shift of MMR vaccination from 9months of age for children participating in community structures to 12months for all children was closely followed since only 2% of 9- to 11-month-old children received a MMR vaccine in 2014compared to 33% in 2012. The second dose of MMR recommended at 16-18months of age rather than between 13and 24months was actually followed by an earlier administration of this dose. At 18-20months of age, 60% received two doses of MMR in 2014versus 41% in 2012. Finally, for meningitis C vaccination, a significant increase of VC was observed in children 15-23months of age (66% in 2014versus 44% in 2012). The simplification of the infant immunization schedule was quickly applied and received excellent support from healthcare professionals. However, this measure alone is still not sufficient to meet the CV objectives defined by the HCSP.

Persistence of rubella and mumps antibodies, following changes in the recommended age for the second dose of MMR vaccine in Portugal.

In Portugal, the recommended age for the second dose of MMR (MMR2) was changed from 10-13 years to 5-6 years for those born in 1994 and afterwards. This study aimed to assess if MMR schedule and time elapsed from the last dose are associated with the concentration of rubella and mumps IgG antibodies. Three Portuguese birth cohorts (convenience samples) were selected for this study (66, 59 and 41 participants born respectively in 1990-1993, 1994-1995 and 2001-2003). Geometric mean concentrations (GMC) for mumps IgG were respectively 36, 30 and 38 RU/ml (P = 0·236) and for rubella IgG were 18, 20 and 17 IU/ml (P = 0·641). For both specific antibodies, no differences were observed with time since MMR2. Receiving MMR2 at 5-6 or 10-13 years was not associated with concentration of both antibodies. The GMC of rubella IgG was lower in males (P = 0·029). Taking into account previous evidence and the logistics needed to change vaccination schedules, it seems reasonable that sustaining very high coverage with two doses of MMR is currently the most pragmatic way to control mumps and rubella rather than any changes to the schedule.

Persistence of measles antibodies, following changes in the recommended age for the second dose of MMR-vaccine in Portugal

In populations vaccinated with two doses of combined measles–mumps–rubella vaccine (MMR), the serum levels of antibodies against measles depend on the vaccination schedule, time elapsed from the last dose and the area-specific epidemiological situation. Variables measuring “schedule” are age at first and second doses of MMR and intervals derived from that. Changes in vaccination schedules have been made in Portugal. The specific objectives of this study were to measure the association between those potential determinants and the concentration of measles-specific IgG antibodies, after the second dose of MMR. Convenience samples of three Portuguese birth cohorts were selected for this study (41, 66 and 60 born, respectively, in 2001–2003, 1990–1993 and 1994–1995). Geometric mean concentrations (GMC) for measles IgG were, respectively, 934, 251 and 144mIU/ml; p<0.001). Anti-measles-IgG serum concentration decreased with time since last vaccination (waning immunity) and was not influenced by any other component of vaccination schedule, namely age at vaccination with the second dose of MMR. Waning levels of measles antibodies have been observed elsewhere but not as fast as it was observed in Portuguese birth cohorts in this study. Changes in the vaccination schedules might have to be considered in the future.

Couverture vaccinale des enfants âgés de 6ans, scolarisés en grande section de maternelle, France, 2005–2006

School-based triennial surveys have been implemented in France since 1999 in order to follow up indicators estimating children's health status, including vaccination coverage.The survey was conducted in 2005-2006 in preschools, using a two-stage cross-sectional sampling design (first sampling schools, with pupils then randomly chosen).Among all the children targeted by the survey, 21,346 of them were selected to show their health booklet (carnet de santé) in which the vaccination part was completed. Vaccination coverage was high for vaccines against tuberculosis (BCG 96.8 %), diphtheria, tetanus, poliomyelitis (four doses: 95.6 %), pertussis (four doses: 95.0 %), Haemophilus influenzae type b (four doses: 89.9 %) and for the first dose of the measles, mumps, and rubella vaccine (MMR 93.7 %, 91.4 %, 91.4 %). It was low for the second dose of MMR (45.1 %, 43.2 %, and 43.3 %) and for hepatitis B (37.9 %). The region where the child attended school, the size of the urban unit, the school sector, the father's profession, and the child's birth rank were associated with MMR (second dose) and hepatitis B coverage.In 2005-2006, vaccination coverage for BCG, DTPolio, pertussis, and Hib was stable and satisfactory in 6-year-old children. MMR (first dose) and hepatitis B coverage were insufficient. MMR coverage (second dose) had increased since 2002 but still needs to be improved.

Comparative Coverage of Supplementary and Universally Recommended Immunizations in Children at 24 Months of Age

The introduction of pneumococcal and meningococcal group C conjugate vaccinations as supplementary (a new category in Swiss immunization recommendations) to universally recommended vaccinations in 2006 prompted this study to investigate their acceptance. The study was performed in 24-month-old healthy children born in the Geneva or Basel areas in Switzerland between January and April 2007. After informed consent had been obtained from caregivers (for this particular study in Basel and in general for providing immunization data in Geneva on an ongoing basis), all universally recommended and supplementary vaccinations administered by ≤24 months of age were analyzed for completeness and timeliness according to set definitions. Sample size calculations and standard statistical tests were applied for comparative data analyses. Of 592 children at the age of 12 months, 94% and 73% had received complete diphtheria-tetanus-pertussis component combination and pneumococcal conjugate vaccinations, respectively. At the age of 24 months, coverage rates for complete booster doses were 77% and 70%, respectively. Rates for MMR doses 1 and 2 at 24 months were 92% and 72%, respectively, and the rate for meningococcal conjugate vaccine (single dose) was 62%. On an average, coverage rates were similar in the 2 study regions except those for pneumococcal conjugate and second dose of MMR, which were approximately 10% higher in Geneva. Compliance with supplementary vaccinations was lower than that with universally recommended vaccinations. This can be explained by the recent introduction of supplementary vaccinations or by the public perception that they are less important than universal vaccinations.

Do childhood vaccines cause thrombocytopenia?

Do childhood vaccines cause thrombocytopenia?

Immunizations and infectious diseases in pediatric liver transplantation

Liver transplantation (LTx) is an established and effective treatment for children with end-stage and metabolic liver disease. Improved surgical techniques and immunosuppressive regimens have led to enhanced short-term and long-term survival rates, which now approach or exceed 90%. Consequently, more children are being referred for LTx, and an increasing numbers of pediatric centers routinely perform this procedure. Infectious complications are an important cause of morbidity and mortality in children undergoing LTx. However, improvements in immune suppression management along with the availability of new antimicrobial agents and diagnostic tools have resulted in improved treatment and preventative regimens, thus reducing the impact of infectious complications on these children. This review provides an overview of the infectious complications and prevention strategies for children undergoing LTx.

Immunogenicity and Safety of a Second Dose of Measles???Mumps???Rubella???Varicella Vaccine in Healthy Children Aged 5 to 6 Years

Two doses of measles-mumps-rubella (MMR) vaccine are recommended for elimination of these diseases in countries with universal mass vaccination; a 2-dose program is also likely to be required for elimination of childhood varicella and has recently been provisionally recommended in the United States. Given the overlap in MMR and varicella vaccination schedules, development of a combined vaccine appears logical and would facilitate the introduction of 2 doses of varicella vaccination in healthy children with no additional injections. The immunogenicity and safety of a second dose of an experimental MMR-varicella (MMRV) vaccine was assessed in an open-label phase III study (208136/017) in healthy children aged 5 to 6 years who had previously received a first dose of either MMRV (N = 48) or a licensed MMR vaccine (N = 45) in the second year of life. After administration of MMRV at 5 to 6 years of age, all subjects were seropositive for measles, rubella and varicella antibodies and only one subject in the MMRV group remained seronegative for mumps antibodies. Ratios of postover prevaccination geometric mean titers for antibodies against measles, mumps and rubella did not differ between the 2 study groups. A 5.2-fold increase (95% confidence interval: 3.5-7.8) in antivaricella antibody geometric mean titers was seen in initially seropositive subjects in the MMRV group after administration of the second vaccine dose. Local symptoms after the second dose of MMRV were more common in the MMRV group than in the MMR group. The incidence of fever was low in both groups compared with that usually seen after a first dose of MMR or MMRV vaccine. This experimental tetravalent MMRV vaccine appears well suited for use in national immunization programs in place of a second dose of MMR or MMR plus varicella in children who have already received a first dose of MMR.

A measles outbreak in children under 15 months of age in La Rioja, Spain, 2005-2006.

This paper describes a measles outbreak in La Rioja, Spain, which began in December 2005 and mainly affected children under 15 months of age who were not yet immunised with MMR vaccine. The measles cases were detected by the mandatory reporting system, under which laboratories must report every confirmed measles case. Cases were classified in accordance with the National Measles Elimination Plan: suspected and laboratory-confirmed. In the period 14 December 2005 to 19 February 2006, 29 suspected cases of measles were investigated, and 18 were confirmed. The mean incubation period was 13.8 days (range: 9 to 18). Of the 18 confirmed cases, only two were in adults. MMR vaccination was recommended for all household contacts, as well as for children aged 6 to 14 months who attended the daycare centres where the cases had appeared. At these centres, the second dose of MMR was administered ahead of schedule for children under three years of age. It was recommended that the first dose of MMR vaccine be administered ahead of schedule for all children aged 9 to 14 months. During an outbreak of measles, children aged 6 months or older, who have not previously been vaccinated against measles, mumps and rubella, should receive a first dose as soon as possible, and those who have had a first dose should receive a second dose as soon as possible, provided that a minimum of one month has elapsed between the two doses.

A comparison of booster immunisation with a combination DTPa-IPV vaccine or DTPa plus IPV in separate injections when co-administered with MMR, at age 4–6 years

This study evaluated GSK's combined DTPa-IPV vaccine (Infanrix™-IPV) given as a fifth consecutive acellular pertussis booster dose in conjunction with the second dose of MMR vaccine (Priorix™) in children aged 4–6 years. The immunogenicity and reactogenicity of this vaccine regimen was compared with separate injections of DTPa and IPV when given concomitantly with MMR. A cohort of 362 children previously primed with four doses of DTPa and OPV, and a single dose of MMR were randomized to receive either DTPa-IPV + MMR ( N = 181) or DTPa + IPV + MMR ( N = 181). Antibody concentrations were measured prior to and 1 month after the booster dose. After immunisation all subjects from both groups had seroprotective antibody levels against diphtheria, tetanus and the three poliovirus serotypes, ≥96% showed vaccine response to PT, FHA and PRN, all were seropositive to mumps and rubella, and all but one subject were seropositive to measles. Immunogenicity results for each component antigen were similar for DTPa-IPV and separately co-administered DTPa and IPV. Local reactions were common with 24.0% and 31.1% of children experiencing swelling >50 mm at the DTPa-IPV and DTPa injection sites, respectively. The DTPa-IPV combination did not increase the incidence or intensity of adverse events compared with separately administered DTPa + IPV. The response to the concomitantly administered MMR vaccine was similar in the two groups and similar to previously reported responses for a second dose of MMR. This combined DTPa-IPV vaccine has a similar reactogenicity profile to DTPa, is immunogenic when given as a booster dose at 4–6 years of age, and has no impact on the immunogenicity of a co-administered second dose of MMR vaccine.

Immunogenicity and Safety of Two Doses of Tetravalent Measles-Mumps-Rubella-Varicella Vaccine in Healthy Children

Combination vaccines against common childhood diseases are widely used, provide an improved coverage, are more convenient and are more cost-effective than multiple injections. We conducted a study to evaluate the safety and immunogenicity of a combined measles-mumps-rubella-varicella (MMRV) candidate vaccine in comparison with the separate administration of licensed measles-mumps-rubella (MMR; Priorix) and varicella (V; Varilrix) vaccines. Healthy children 12-18 months of age received 2 doses of MMRV vaccine (3 lots) 6-8 weeks apart (MMRV group) or 1 dose of MMR vaccine administered concomitantly with 1 dose of varicella vaccine, followed by a second dose of MMR at 6-8 weeks later (MMR+V group). Local symptoms (redness, pain and swelling) were recorded for 4 days after vaccination, and fever (any, axillary temperature > or =37.5 degrees C or rectal temperature > or =38.0 degrees C; grade 3, axillary temperature >39.0 degrees C or rectal temperature >39.5 degrees C) was monitored daily for 15 days. Other adverse events were monitored for 6 weeks. A total of 494 children were vaccinated (371 in the MMRV group and 123 in the MMR+V group. Two doses of MMRV vaccine were at least as immunogenic as 2 doses of MMR and 1 dose of varicella vaccine. After the second dose, all children had seroconverted to measles, rubella and varicella in both vaccine groups, and 98% versus 99% had seroconverted to mumps in the MMRV versus the MMR+V group, respectively. The MMRV vaccine did not induce an increased local or general reactogenicity compared with the separate administration, although a higher incidence of low grade fever was seen after the first dose in the MMRV group (67.7% after MMRV versus 48.8% after MMR+V; P < 0.05), this was not observed for grade 3 fever (11.6% after MMRV versus 10.6% after MMR+V; P = 0.87). After the second dose, no differences in incidence of fever were found in either MMRV or MMR+V groups. Administration of 2 doses of the combined MMRV vaccine was as immunogenic and well-tolerated as separate injections of MMR and varicella vaccine.

Measles in Saudi Arabia: from control to elimination

This article describes the tremendous efforts made in the field of measles immunization in Saudi Arabia in the past 20 years, from the control phase to the elimination phase. Mandatory measles vaccination with one-dose Schwartz vaccine was introduced in 1982 by a royal decree, a step aimed at increasing vaccine coverage. In 1991, a two-dose schedule was implemented using Edmonston-Zagreb measles vaccine, with a first dose at 6 months to protect children younger than 9 months and a second dose of MMR at 12 months of age to protect those who did not respond to the first dose. A marked reduction in the epidemic peak and a shift of infection to older age were noticed. But the same data showed that 50% of measles cases in the 1- to 4-year age group occurred in vaccinated children. In 1998, with the start of elimination phase, an MMR campaign was launched in two phases, targeting school children in 1998 (secondary schools) and in 2000 (primary and intermediate schools). Evaluation of the MMR campaign and surveillance data was reflected in the measles immunization policy by shifting the age of measles immunization to 12 months and to preschool using the two-dose MMR schedule.

Rubella in England, Scotland and Wales.

Rubella vaccine was offered to schoolgirls in the United Kingdom (UK) from 1970, with antenatal testing and postpartum vaccination for susceptible women introduced during the 1970s. Mass vaccination with MMR of children aged 12-15 months was introduced in 1988; schoolgirl vaccination was discontinued in 1996 and replaced by a second dose of MMR for pre-school children; postpartum vaccination of susceptible women identified through antenatal testing continues. Rubella was made a notifiable disease in 1988, and is monitored through clinical and laboratory reports; data are available on rubella associated terminations and congenital rubella syndrome(CRS) births, rubella susceptibility in population subgroups, and vaccine uptake. Reported cases of CRS declined from about 50 a year 1971-75 to just over 20 a year 1986-90, and rubella associated terminations from an average of 750 to 50 a year. About 40 infants with CRS have been reported since 1991; about a third of their mothers were infected abroad, most in their country of origin (imported infections), a third were born abroad but acquired infection in the UK, and a third were UK-born. Women living in the UK who were born abroad have much higher rubella susceptibility rates than UK-born women. Although there is currently very little rubella infection circulating, uptake of MMR has dropped by over 10% since 1995. If rubella starts to circulate again, immigrant women will be at increased risk of acquiring infection in pregnancy.

Epidemiology of measles, mumps and rubella in Italy

A serosurvey for measles, mumps and rubella was conducted in Italy; incidence based on statutory notifications over the last three decades was also calculated. In Italy the diseases followed an endemic-epidemic pattern, with an incidence peak every 2-4 years, and had a limited reduction of incidence attributable to childhood immunization. Lower notification rates were observed in the Southern regions. This is possibly related to greater under notification in the South and is confirmed by our seroprevalence data. Incidence of measles and rubella and proportion of cases among young adults increased significantly in the three decades considered, but not for mumps. Serological data confirmed that these infections are still very frequent in Italy, without significant geographic variation in the country. In the age groups 2-4 and 5-9 years the percentage of individuals still susceptible to each virus was higher than 30%. The proportion of susceptible subjects older than 15 years was similar for the three infections (6.1, 11.7 and 8.8% for measles, mumps and rubella, respectively). The low vaccine coverage for rubella and measles in Italy has so far only partially affected the occurrence of the diseases. No impact of mumps vaccination is visible. The average number of deaths, for each disease, has decreased during the three study periods. Today the priority in Italy is to halt the progressive increase of the mean age of acquisition of the three infections, to eliminate differences in coverage among regions and to conform to European standards. This will be achieved through a combination of increasing MMR vaccine coverage before 2 years of age, implementing vaccination campaigns for low seroprevalence age groups, and/or introducing a second dose of MMR, depending on the level of current MMR coverage.

Immunity to mumps before and after MMR vaccination at 12 years of age in the first generation offered the two-dose immunization programme

Sweden was the first country in the world to introduce a two-dose programme of vaccination against measles, mumps and rubella with a combined vaccine (MMR). It was commenced in 1982 and the vaccination was carried out at the ages of 18 months and 12 years. In 1992–1993 the first age-group vaccinated at 18 months reached the age of 12 and accordingly received a second dose of MMR. A total of 382 children participated in the present study. Sero-immunity against mumps was studied by testing neutralizing antibodies using serial dilutions inoculated into cell cultures before and after the 12-year vaccination. Of the 229 children earlier vaccinated (group A), 27% lacked demonstrable antibodies before the booster. Of those without documented vaccination records (group B), 56% were seronegative before vaccination. After vaccination, 93% of group A and 86% of group B were seropositive (titre ⩾2). In the seronegative children, whether vaccinated earlier or not, the seroconversion was ca 75%. Previously unvaccinated children positive before vaccination and thus likely to be naturally immune had a higher mean-titre both before and after vaccination than the seropositive chlidren earlier vaccinated. So far, the two-dose programme has proceeded as expected.