Live, attenuated mumps-virus vaccine. 3. Clinical and serologic aspects in a field evaluation

Transforming vaccinology

The COVID-19 pandemic placed the field of vaccinology squarely at the center of global consciousness, emphasizing the vital role of vaccines as transformative public health tools. The impact of vaccines was recently acknowledged by the award of the 2023 Nobel Prize in Physiology or Medicine to Katalin Kariko and Drew Weissman for their seminal contributions to the development of mRNA vaccines. Here, we provide a historic perspective on the key innovations that led to the development of some 27 licensed vaccines over the past two centuries and recent advances that promise to transform vaccines in the future. Technological revolutions such as reverse vaccinology, synthetic biology, and structure-based design transformed decades of vaccine failures into successful vaccines against meningococcus B and respiratory syncytial virus (RSV). Likewise, the speed and flexibility of mRNA vaccines profoundly altered vaccine development, and the advancement of novel adjuvants promises to revolutionize our ability to tune immunity. Here, we highlight exciting new advances in the field of systems immunology that are transforming our mechanistic understanding of the human immune response to vaccines and how to predict and manipulate them. Additionally, we discuss major immunological challenges such as learning how to stimulate durable protective immune response in humans.

Mumps-specific IgG, IgG subclasses and neutralization titres to the vaccine and outbreak mumps strains differ in vaccinated healthy controls, breakthrough mumps infection cases and naturally infected individuals

BACKGROUND

Despite widespread use of the mumps vaccine resulting in significant reduction in the incidence of symptomatic mumps infection, large outbreaks continue to occur in highly vaccinated populations.

OBJECTIVES

We examined the mumps-specific IgG, IgG subclasses and neutralization titres to the outbreak Genotype G5 and Jeryl Lynn vaccine (Genotype A) mumps strains.

STUDY DESIGN

Sera from 207 individuals were classified into five distinct cohorts: healthy controls and mumps cases of 5-17 years and 18-25 years, and naturally infected individuals of 50+ years. Mumps specific IgG and IgG subclass levels were measured using modified ELISA assays with lysates and nucleoprotein antigens from both the mumps vaccine and circulating Genotype G5 strains. All sera were investigated for in vitro neutralizing antibody titres (GMT) using focus reduction neutralization assays. Data was analysed using the Kruskal-Wallis test and pairwise Wilcoxon tests.

RESULTS

Mumps cases had higher mumps IgG levels compared to controls, to both the vaccine and outbreak strains, however levels decreased with age. Mumps IgG3 levels were significantly raised in mumps cases (p < 0.001). Neutralization titres were lower to the outbreak strain in all cohorts with titres markedly lower in the mumps cohorts compared to healthy controls. Mean GMT to the vaccine strain increased with age. The naturally infected group displayed the highest GMT to the JL vaccine and the lowest GMT to the outbreak strain.

CONCLUSIONS

Antigenic differences between mumps vaccine strain and circulating mumps viruses decrease the cross-neutralization capacity of vaccine-induced antibodies which may play a role in breakthrough infection.

Mumps virus-specific immune response outcomes and sex-based differences in a cohort of healthy adolescents

Despite high levels of MMR-II usage in the US, mumps outbreaks continue to occur. Evidence suggests that mumps vaccine-induced humoral immunity wanes over time. Relatively few studies have examined cell-mediated immunity or reported on sex-based differences. To better understand sex-based differences in the immune response to mumps vaccine, we measured neutralizing antibody titers and mumps-specific cytokine/chemokine responses in a cohort of 748 adolescents and young adults after two doses of MMR vaccine. We observed significantly higher neutralizing antibody titers in females than in males (120.8 IU/mL, 98.7 IU/mL, p = 0.038) but significantly higher secretion levels of MIP-1α, MIP-1β, TNFα, IL-6, IFNγ, and IL-1β in males compared to females. These data demonstrate that sex influences mumps-specific humoral and cell-mediated immune response outcomes, a phenomenon that should be considered during efforts to improve vaccines and prevent future outbreaks.

Mumps Outbreaks in Vaccinated Populations-Is It Time to Re-assess the Clinical Efficacy of Vaccines?

History illustrates the remarkable public health impact of mass vaccination, by dramatically improving life expectancy and reducing the burden of infectious diseases and co-morbidities worldwide. It has been perceived that if an individual adhered to the MMR vaccine schedule that immunity to mumps virus (MuV) would be lifelong. Recent mumps outbreaks in individuals who had received two doses of the Measles Mumps Rubella (MMR) vaccine has challenged the efficacy of the MMR vaccine. However, clinical symptoms, complications, viral shedding and transmission associated with mumps infection has been shown to be reduced in vaccinated individuals, demonstrating a benefit of this vaccine. Therefore, the question of what constitutes a good mumps vaccine and how its impact is assessed in this modern era remains to be addressed. Epidemiology of the individuals most affected by the outbreaks (predominantly young adults) and variance in the circulating MuV genotype have been well-described alluding to a collection of influences such as vaccine hesitancy, heterogeneous vaccine uptake, primary, and/or secondary vaccine failures. This review aims to discuss in detail the interplay of factors thought to be contributing to the current mumps outbreaks seen in highly vaccinated populations. In addition, how mumps diagnoses has progressed and impacted the understanding of mumps infection since a mumps vaccine was first developed, the limitations of current laboratory tests in confirming protection in vaccinated individuals and how vaccine effectiveness is quantified are also considered. By highlighting knowledge gaps within this area, this state-of-the-art review proposes a change of perspective regarding the impact of a vaccine in a highly vaccinated population from a clinical, diagnostic and public perspective, highlighting a need for a paradigm shift on what is considered vaccine immunity.

Mumps: an Update on Outbreaks, Vaccine Efficacy, and Genomic Diversity

Mumps is an acute viral infection characterized by inflammation of the parotid and other salivary glands. Persons with mumps are infectious from 2 days before through 5 days after parotitis onset, and transmission is through respiratory droplets. Despite the success of mumps vaccination programs in the United States and parts of Europe, a recent increase in outbreaks of mumps virus infections among fully vaccinated populations has been reported. Although the effectiveness of the mumps virus component of the measles-mumps-rubella (MMR) vaccine is suboptimal, a range of contributing factors has led to these outbreaks occurring in high-vaccination-coverage settings, including the intensity of exposure, the possibility of vaccine strain mismatch, delayed implementation of control measures due to the timeliness of reporting, a lack of use of appropriate laboratory tests (such as reverse transcription-PCR), and time since last vaccination. The resurgence of mumps virus infections among previously vaccinated individuals over the past decade has prompted discussions about new strategies to mitigate the risk of future outbreaks. The decision to implement a third dose of the MMR vaccine in response to an outbreak should be considered in discussions with local public health agencies. Traditional public health measures, including the isolation of infectious persons, timely contact tracing, and effective communication and awareness education for the public and medical community, should remain key interventions for outbreak control. Maintaining high mumps vaccination coverage remains key to U.S. and global efforts to reduce disease incidence and rates of complications.

Mumps: MMR vaccination and genetic diversity of mumps virus, 2007-2011 in Catalonia, Spain

BACKGROUND

Mumps is a vaccine-preventable disease but outbreaks have been reported in persons vaccinated with two doses of MMR vaccine. The objective was to describe the demographic features, vaccination effectiveness and genetic mumps virus diversity among laboratory-confirmed cases between 2007 and 2011 in Catalonia.

METHODS

Cases and outbreaks of mumps notified to the notifiable diseases system of Catalonia between 2007 and 2011 retrospectively registered were included. Public health care centres provided written immunization records to regional public health staff to determine the vaccination history. Saliva and serum specimens were collected from suspected cases for laboratory-confirmation using real-time reverse-transcriptase PCR (rtRT-PCR) or serological testing. Phylogenetic analysis of the complete SH gene (316 nucleotides) and complete coding HN protein (1749 nucleotides) sequences was made. Categorical variables were compared using the Chi-square or Fisher's tests and continuous variables using the Student test. Vaccination effectiveness by number of MMR doses was estimated using the screening method.

RESULTS

During the study period, 581 confirmed cases of mumps were notified (incidence rate 1.6 cases/100,000 persons-year), of which 60% were male. Three hundred sixty-four laboratory-confirmed cases were reported, of which 44% were confirmed by rtRT-PCR. Of the 289 laboratory-confirmed cases belonging to vaccination cohorts, 33.5% (97) had received one dose of MMR vaccine and 50% (145) two doses. Based on phylogenetic analyses of 316-nucleotide and 174-nucleotide SH sequences, the viruses belonging to viral genotypes were: genotype G (126), genotype D (23), genotype H (2), genotype F (2), genotype J (1), while one remained uncharacterized. Amino acid differences were detected between circulating strains and the Jeryl Lynn vaccine strains, although the majority of amino acid substitutions were genotype-specific. Fifty-one outbreaks were notified that included 324 confirmed mumps cases. Genotype G was the most frequent genotype detected. The family (35%), secondary schools (25%) and community outbreaks (18%) were the most frequent settings.

CONCLUSIONS

Our study shows that genotype G viruses are the most prevalent in Catalonia. Most cases occurred in people who had received two doses of MMR, suggesting inadequate effectiveness of the Jeryl Lynn vaccine strain. The possible factors related are discussed.

Differential durability of immune responses to measles and mumps following MMR vaccination

The development and wide-spread use of mumps vaccine resulted in a dramatic and sustained decrease in the incidence of mumps disease; however, since 2000, an increase in the size and number of mumps outbreaks in the United States and other countries has sparked renewed interest in the durability of mumps-specific immunity elicited by mumps vaccination. The most likely explanation for mumps cases in previously immunized persons may be secondary vaccine failure, or waning immunity. In the current study, we examined changes in markers of measles and mumps immunity at two timepoints, approximately 7 and 17 years after two-dose MMR-II® vaccination, in a cohort of 98 healthy adults. Our results indicate that mumps IgG titers exhibited a large and significant decline during this time period, while mumps neutralizing Ab titers were relatively stable. There was a similar discrepancy with measles-specific immune responses. For both pathogens, neutralizing antibody titers were fairly low and, given the length of time since vaccination, may have already declined. These data suggest that specific immune outcomes may wane at different rates and highlight our currently incomplete understanding of protective immune responses to mumps and measles.

Knowledge gaps persist and hinder progress in eliminating mumps

Mumps, a common childhood disease in the pre-vaccine era that causes swelling of the parotid salivary glands, can lead to orchitis, viral meningitis, and sensorineural deafness. While the incidence of disease decreased dramatically after the vaccine was added to standard vaccination schedules, the disease has made a substantial resurgence in recent years. As a result, it becomes critical to examine the factors involved in recurring outbreaks. Although low and incomplete vaccination coverage may be a key reason, it does not fully explain the issue due to the high rate of occurrence in populations with high vaccination coverage rates. Multiple studies suggest that waning immunity and secondary vaccine failure play a large role, the effects of which were previously masked by subclinical boosting. Significant knowledge gaps persist around the exact role and mechanism of waning immunity and demonstrate the need for more research in this area, as well as a reevaluation of mumps vaccine policy.

Measles, mumps, and rubella virus vaccine (M-M-R™II): a review of 32 years of clinical and postmarketing experience

M-M-R™II (measles, mumps, and rubella virus vaccine live; Merck, Sharp, & Dohme Corp.) is indicated for simultaneous vaccination against measles, mumps, and rubella in individuals ≥ 12 months of age. Before the vaccine era, these viruses infected most exposed individuals, with subsequent morbidity and mortality. One of the greatest achievements of public health has been to eliminate these 3 diseases in large geographic areas. The safety profile of M-M-R™II is described using data from routine global postmarketing surveillance. Postmarketing surveillance has limitations (including incomplete reporting of case data), but allows collection of real-world information on large numbers of individuals, who may have concurrent medical problems excluding them from clinical trials. It can also identify rare adverse experiences (AEs). Over its 32-year history, ≈ 575 million doses of M-M-R™II have been distributed worldwide, with 17,536 AEs voluntarily reported for an overall rate of 30.5 AEs/1,000,000 doses distributed. This review provides evidence that the vaccine is safe and well-tolerated.

Longitudinal analysis of antibody response to immunization in paediatric survivors after allogeneic haematopoietic stem cell transplantation

The long-term antibody responses to re-immunization in recipients of allogeneic haematopoietic stem cell transplantation (allo-HSCT) have not been well studied. We prospectively and longitudinally evaluated the antibody responses to eight vaccine antigens (diphtheria, tetanus, pertussis, measles, mumps, rubella, hepatitis B, and poliovirus) and assessed the factors associated with negative titres in 210 allo-HSCT recipients at St. Jude Children's Research Hospital. Antibody responses lasting for more than 5 years after immunization were observed in most patients for tetanus (95.7%), rubella (92.3%), poliovirus (97.9%), and, in diphtheria-tetanus-acellular pertussis (DTaP) recipients, diphtheria (100%). However, responses to pertussis (25.0%), measles (66.7%), mumps (61.5%), hepatitis B (72.9%), and diphtheria in tetanus-diphtheria (Td) recipients (48.6%) were less favourable, with either only transient antibody responses or persistently negative titres. Factors associated with vaccine failure were older age at immunization; lower CD3, CD4 or CD19 counts; higher IgM concentrations; positive recipient cytomegalovirus serology; negative titres before immunization; acute or chronic graft-versus-host disease; and radiation during preconditioning. These response patterns and clinical factors can be used to formulate re-immunization and monitoring strategies. Patients at risk for vaccine failure should have long-term follow-up; those with loss of antibody response or no seroconversion should receive booster immunizations.

Immune responses to mumps vaccine in adults who were vaccinated in childhood

BACKGROUND

In a mumps outbreak in the United States, many infected individuals were adults who had received 2 doses of mumps vaccine. The persistence of cellular immunity to mumps vaccine has not been defined.

METHODS

This was an observational, nonrandomized cohort study evaluating cell-mediated and humoral immunity to mumps in 10 vaccinated and 10 naturally immune adults. Mumps-specific T cell activation and interferon (IFN)-gamma production were measured using lymphoproliferative and flow cytometry assays, and mumps immunoglobulin (Ig) G was measured using enzyme-linked immunosorbent assay.

RESULTS

T cell immunity to mumps was high in both groups; 70% of vaccinated and 80% of naturally immune individuals had a positive (> or =3) stimulation index (SI) (P = 1.0). The mean percentages of mumps-specific CD4+ T cells that expressed CD69 and produced IFN-gamma were equivalent in the 2 groups: 0.06% and 0.12%, respectively (P = .11). The mean SIs in the groups were also equivalent, although IFN-gamma concentrations from cultures stimulated with mumps antigen were higher in naturally immune adults than in vaccinated adults (P < or = .01). All adults were positive for mumps IgG.

CONCLUSION

T and B cell immunity to mumps was detected in adults at least 10 years after immunization. Except for IFN-gamma release, responses in vaccinated adults paralleled those observed in naturally immune individuals.

The epidemiology of mumps in Italy

In Italy, although vaccination has been recommended for a number of years, vaccination coverage for mumps is still sub-optimal. The objective of the present study was to evaluate the seroprevalence of mumps antibodies in the Italian population, stratified by age, gender and geographical area. The proportion of individuals positive for mumps antibodies remained stable in the age classes 0-11 months and 1 year (25.4% and 30.8%, respectively) and showed a continuous increase after the second year of life. The percentage of susceptible individuals was higher than 20% in persons 2-14 years of age and exceeded 10% in persons 15-39 years of age. No statistically significant differences were observed by gender or geographical area. Comparison between these results and the data obtained from a 1996 survey showed a statistically significant increase in seroprevalence in the age class 2-4 years. No changes were observed in the other age-groups. The results of this study confirm that the efforts made in recent years to improve vaccination coverage within the second year of life should be strengthened.

The effectiveness of the mumps component of the MMR vaccine: a case control study

In 1998/1999, an outbreak of mumps occurred among children of a religious community in North East London. A case control study was conducted to assess the effectiveness of the mumps component of the MMR vaccine. One hundred and sixty-one cases of mumps were identified and 192 controls were selected. Fifty-one percent of cases and 77% of controls had a history at least one MMR vaccination. The observed effectiveness of any MMR vaccination adjusted for age, sex and general practice was 69% (95% CI: 41-84%). This is consistent with the results of other observational studies of mumps containing vaccines, but lower than the immunogenicity of mumps vaccines reported by clinical trials. This discrepancy is because observational studies tend to underestimate vaccine effectiveness, and because immunogenicity is not necessarily an accurate biological marker of vaccine effectiveness. Two doses of vaccine were more effective (88% (95% CI: 62-96%)) than a single dose (64% (95% CI: 40-78%)). The current two-dose vaccination programme remains the best method for controlling mumps infection in the community.

Mumps virus-specific antibody titers from pre-vaccine era sera: comparison of the plaque reduction neutralization assay and enzyme immunoassays

Mumps virus-neutralizing antibodies are believed to be the most predictable surrogate marker of protective immunity. However, assays used to detect neutralizing antibodies, such as the plaque reduction neutralization (PRN) assay, are labor- and time-intensive and consequently are often supplanted by the more rapid and inexpensive enzyme immunoassay (EIA) technique. For virus infections for which international antibody standards exist and are bridged to clinical studies of protection (e.g., measles and rubella), the EIA has been successfully used to determine immune surrogate endpoints, yet no such international reference exists for mumps serology. Since both virus-neutralizing and nonneutralizing antibodies are measured in the EIA, in the absence of a mumps serological standard, the EIA may be prone to yielding false-positive results when utilized for assessing surrogate markers of protective immunity. Moreover, since mumps virus-specific antibody titers are generally low in comparison to antibody levels induced by other viruses and EIA procedures often employ relatively high serum dilution factors, the EIA may be prone to yielding false-negative results. To examine these issues, a PRN assay and two commercially available EIA kits were used to evaluate wild-type mumps virus serological responses in human serum samples from the pre-mumps vaccine era. Our results indicate that the PRN assay is a more sensitive and specific method of measuring serological responses to wild-type mumps virus.

No definitive evidence for L-Zagreb mumps strain associated aseptic meningitis: a review with special reference to the da Cunha study

The study by da Cunha et al. published in 2002 reported that MMR vaccine containing L-Zagreb mumps strain manufactured by Serum Institute of India Ltd. caused a high incidence of aseptic meningitis (AM) from routine surveillance during two mass immunization campaigns (MIC) conducted in 1998 in two states in Brazil. Since the results were contrary to those in India, Egypt and Bahamas, a critical analysis of the study was done. Several inconsistencies were found in the study, which undermined the conclusions drawn. Two similar studies from Brazil reported similar results. Review of these studies and those done on the vaccine from Zagreb, Croatia showed that in no study the L-Zagreb mumps virus has been isolated from cerebrospinal fluid (CSF) of an AM case. Isolation of the vaccine virus is necessary for definite causal association of AM with the vaccine. There is no such evidence to causally link MMR vaccine containing L-Zagreb mumps strain with AM.

A review of licensed viral vaccines, some of their safety concerns, and the advances in the development of investigational viral vaccines

Viral vaccines could be considered among the most important medical achievements of the 20th century. They have prevented much suffering and saved many lives. Although some curative antiviral drugs exist, we desperately depend on efforts by academic, governmental and industrial scientists in the advancement of viral vaccines in the prevention and control of infectious diseases. In the next decade, we hope to see advancement in the development of current and investigational viral vaccines against childhood and adult infections. In this article, we will review the licensed viral vaccines, some of their safety concerns, and the advances in the development of investigational viral vaccines.

Vaccines and immunotherapies for the prevention of infectious diseases having cutaneous manifestations

Although the development of antimicrobial drugs has advanced rapidly in the past several years, such agents act against only certain groups of microbes and are associated with increasing rates of resistance. These limitations of treatment force physicians to continue to rely on prevention, which is more effective and cost-effective than therapy. From the use of the smallpox vaccine by Jenner in the 1700s to the current concerns about biologic warfare, the technology for vaccine development has seen numerous advances. The currently available vaccines for viral illnesses include Dryvax for smallpox; the combination measles, mumps, and rubella vaccine; inactivated vaccine for hepatitis A; plasma-derived vaccine for hepatitis B; and the live attenuated Oka strain vaccine for varicella zoster. Vaccines available against bacterial illnesses include those for anthrax, Haemophilus influenzae, and Neisseria meningitidis. Currently in development for both prophylactic and therapeutic purposes are vaccines for HIV, herpes simplex virus, and human papillomavirus. Other vaccines being investigated for prevention are those for cytomegalovirus, respiratory syncytial virus, parainfluenza virus, hepatitis C, and dengue fever, among many others. Fungal and protozoan diseases are also subjects of vaccine research. Among immunoglobulins approved for prophylactic and therapeutic use are those against cytomegalovirus, hepatitis A and B, measles, rabies, and tetanus. With this progress, it is hoped that effective vaccines soon will be developed for many more infectious diseases with cutaneous manifestations.

Personal historical chronicle of six decades of basic and applied research in virology, immunology, and vaccinology

The sciences of vaccinology and of immunology were created just two centuries ago by Jenner's studies of prevention of smallpox by inoculation with cowpox virus. This rudimentary beginning was expanded greatly by the giants of late 19th and early 20th centuries biomedical sciences. The period from 1930 to 1950 was a transitional era with the introduction of chick embryos and minced tissues for propagating viruses and rickettsiae in vitro for vaccines. Modern era vaccinology began about 1950 as a continuum of notable advances made during the 1940s and World War II. Present vaccinology is based largely on breakthroughs in cell culture, bacterial polysaccharide chemistry, molecular biology, and immunology. By invitation, the author, who is a microbe hunter in fact, was asked to chronicle his six decades of pioneering achievements in basic and applied virology, bacteriology, immunology, molecular biology, epidemiology, and cancer, with special reference to the pioneering creation of most of the present day vaccines. Knowledge of the past may guide the present and future. This chronicle will have achieved its legacy if it helps others to understand the why and how of the past that may help to create the substance of the future.

Pediatric immunizations

The record of disease prevention in children is an impressive testament to our universal immunization program. However, these successes are being threatened by rates of vaccination in some areas of the country that are substantially less than those seen in the developing world. Unless the pediatric immunization rates are improved, epidemics of other vaccine-preventable diseases will recur, as evidenced by the measles outbreaks. Although the tools needed for disease prevention are available, the means for their delivery are lacking. It is the obligation of us all to immunize the nation's children.

Rubella and mumps vaccines

As a fetal infection occurring during early pregnancy, rubella's potential for teratogenicity is unparalleled. In the postnatal period it is a relatively benign disease. Mumps, on the other hand, causes moderate morbidity and occasional mortality. Both infections cause considerable morbidity and disruption in the lives of young people gathered for group activities. Widespread use of safe and effective live attenuated vaccines has dramatically reduced the incidence of rubella, congenital rubella, and mumps in the United States. Nevertheless, significant numbers of young children, especially in areas of urban and rural immigration and poverty, fail to be immunized in a timely fashion; and some adolescents and young adults remain susceptible either because they escaped immunization in childhood or are primary vaccine failures. These individuals remain the source of individual cases and small outbreaks of rubella and mumps. For total eradication of these infections, we need to intensify vaccine efforts and to maintain surveillance efforts for mumps, rubella, and congenital rubella syndrome.

A controlled trial for evaluating two live attenuated mumps-measles vaccines (Urabe Am 9-Schwarz and Jeryl Lynn-Moraten) in young children

A prospective, randomised clinical trial was conducted to evaluate the efficacy of two live attenuated mumps-measles vaccines, the Urabe Am 9-Schwarz and the Jeryl Lynn-Moraten vaccine, in 400 young children aged 9 months-4.5 years (median 13.4 months). Antibody responses to both vaccine components were measured by the enzyme-linked immunosorbent assay (ELISA); 96.9% of the seronegative children who received the Urabe Am 9-Schwarz vaccine showed satisfactory mumps antibody responses compared to 90% of the Jeryl Lynn-Moraten vaccine recipients (P less than .01). Similar proportions of both groups, 98.5% and 96.8%, respectively, developed measles virus specific antibodies. Both vaccines were equally well tolerated and clinically acceptable.

Evaluation in young children of the Urabe Am 9 strain of live attenuated mumps vaccine in comparison with the Jeryl Lynn strain

Urabe Am 9, a new strain of mumps vaccine, originally developed in Japan, was evaluated in children 14 to 20 months of age in a comparative trial with the Jeryl Lynn strain. Both vaccines performed well. The antibody responses were measured using a neutralization test and a haemolysis-in-gel test. The seroconversion rates at six weeks, as detected with either one or both tests, were 55/58 (94.8%) after the Urabe Am 9 and 58/60 (96.7%) after the Jeryl Lynn vaccine. Only mild infrequent adverse reactions were observed. It is concluded that both strains of live attenuated mumps vaccine are immunogenic and well-tolerated in this age group.

Antibody response after application of a new live attenuated mumps vaccine (Pariorix) measured by enzyme-linked immunosorbent assay (ELISA)

Mumps virus specific antibody concentrations were determined by enzyme-linked immunosorbent assay (ELISA), hemolysis-in-gel (HIG) test, and hemagglutination-inhibition (HI) test in 17 adult volunteers before and after vaccination with a new live mumps vaccine, Pariorix. The results of the present study indicate that the strain Urabe-Am 9 of the mumps virus (Pariorix) induces antibodies in 100% of seronegative adults when measured by ELISA and in 70.6% and 64.7% in HIG and HI, respectively. ELISA is therefore a very sensitive and reliable method for the demonstration of sero-conversion after vaccination. The vaccine was well tolerated and clinically acceptable in the group of adult volunteers.

Epidemiology of mumps in the Netherlands

In a Dutch population group neutralizing antibodies against mumps virus were determined by a plaque reduction technique, which proved reproducible, sensitive and specific. The results with sera of about 800 suburban children show that mumps is acquired at an early age with peak acquisition rates between the ages of four and six years. Over 90% have acquired mumps before the age of 14 years. More than 95% of about 1000 adults (18--65 years) have neutralizing antibodies. The relatively constant median titre suggests that antibodies persist during life. During a family study 77 clinical and 18 subclinical cases were observed. In families with index cases the attack rate was 26/37 = 0.71. Eleven children (excluding six babies) escaped infection. The mean attack rate during the epidemic was 0.30. The mean titre of mumps neutralizing antibody is maximal during the first year after the disease but declines during childhood. Mothers exposed to mumps in the family occasionally showed a significant rise in titre. Some seronegative mothers remained seronegative after exposure.

A field with a liver measles-mumps-rubella vaccine

Three lots of Lirutrin (measles-mumps-rubella live, attenuated virus vaccine) were evaluated in a double-blind, placebo-controlled clinical study involoving 273 children. The vaccine consisted of a combination of Schwarz strain measles, Jeryl Lynn strain mumps, and Cendehill strain rubella vaccine viruses. The frequency of positive clinical findings was essentially the same in susceptiable vaccinees, immune vaccinees, and placebo recipients; indicating that the observed symptoms were not caused by the vaccine. Antibody assay of paired serum samples revealed that measles, mumps, and rubella seroconverison rates in triple susceptible vaccinees were excellent, ranging from 96 to 98 per cent with all three lots combined. Results of this study show that Lirutrin trivalent vaccine is well tolerated and highly effective.

A field trial of combined measles-mumps-rubella vaccine. Satisfactory immunization with 188 children in Chile

This report presents confirming evidence for the immunizing value of a trivalent combined measles-mumps-rubella vaccine (M-M-R), based on studies with 188 children in Chile. All of the children de veloped antibody against measles virus and 96 per cent developed antibodies against mumps and rubella. No clinical reaction occurred other than that expected to follow measles vaccine given alone.