Introduction of Two-Dose Mumps-Containing Vaccine into Routine Immunization Schedule in Quzhou, China, Using Cox-Proportional Hazard Model.

Mumps is a vaccine-preventable disease caused by the mumps virus, but the incidence of mumps has increased among the children who were vaccinated with one-dose measles-mumps-rubella (MMR) in recent years. In this study, we analyzed the influence of different doses of mumps-containing vaccine (MuCV) against mumps using Cox-proportional hazard model. We collected 909 mumps cases of children who were born from 2006 to 2010 and vaccinated with different doses of MuCV in Quzhou during 2006-2018, which were all clinically diagnosed. Kaplan-Meier survival methods and Cox-proportional hazard model were used to estimate the hazard probabilities. Kaplan-Meier curves showed that the cumulative hazard of male and female has no difference; lower hazards were detected among those who were vaccinated with two-dose MuCV, born in 2006, and infected after supplementary immunization activities (SIA). Cox-proportional hazard regression suggested that onset after SIA, born in 2006, and vaccinated with two-dose MuCV were protective factors against infection even after adjusting for potential confounding effects. Our study showed that it was necessary to revise the diagnostic criteria of mumps and identify RT-PCR as the standard for mumps diagnosis in China. We suggested that routine immunization schedule should introduce two doses of MMR and prevaccination screening should be performed before booster immunization in vaccinated populations.

Pediatricians' Knowledge and Practices Related to Mumps Diagnosis and Prevention.

OBJECTIVES: To assess pediatricians' mumps knowledge and testing practices, to identify physician and practice characteristics associated with mumps testing practices, and to assess reporting and outbreak response knowledge and practices. STUDY DESIGN: Between January and April 2020, we surveyed a nationally representative network of pediatricians. Descriptive statistics were generated for all items. The χ2 test, t tests, and Poisson regression were used to compare physician and practice characteristics between respondents who would rarely or never versus sometimes or often/always test for mumps in a vaccinated 17-year-old with parotitis in a non-outbreak setting. RESULTS: The response rate was 67% (297 of 444). For knowledge, more than one-half of the pediatricians responded incorrectly or "don't know" for 6 of the 9 true/false statements about mumps epidemiology, diagnosis, and prevention, and more than one-half reported needing additional guidance on mumps buccal swab testing. For testing practices, 59% of respondents reported they would sometimes (35%) or often/always (24%) test for mumps in a vaccinated 17-year-old with parotitis in a non-outbreak setting; older physicians, rural physicians, and physicians from the Northeast or Midwest were more likely to test for mumps. Thirty-six percent of the pediatricians reported they would often/always report a patient with suspected mumps to public health authorities. CONCLUSIONS: Pediatricians report mumps knowledge gaps and practices that do not align with public health recommendations. These gaps may lead to underdiagnosis and underreporting of mumps cases, delaying public health response measures and contributing to ongoing disease transmission.

Mumps Orchitis: Clinical Aspects and Mechanisms.

The causative agent of mumps is a single-stranded, non-segmented, negative sense RNA virus belonging to the Paramyxoviridae family. Besides the classic symptom of painfully swollen parotid salivary glands (parotitis) in mumps virus (MuV)-infected men, orchitis is the most common form of extra-salivary gland inflammation. Mumps orchitis frequently occurs in young adult men, and leads to pain and swelling of the testis. The administration of MuV vaccines in children has been proven highly effective in reducing the incidence of mumps. However, a recent global outbreak of mumps and the high rate of orchitis have recently been considered as threats to male fertility. The pathogenesis of mumps orchitis remains largely unclear due to lack of systematic clinical data analysis and animal models studies. The alarming increase in the incidence of mumps orchitis and the high risk of the male fertility have thus become a major health concern. Recent studies have revealed the mechanisms by which MuV-host cells interact and MuV infection induces inflammatory responses in testicular cells. In this mini-review, we highlight advances in our knowledge of the clinical aspects and possible mechanisms of mumps orchitis.

Effect of change in cell substrate on the critical quality attributes of L-Zagreb Mumps vaccine manufactured using parallel plate bioreactor.

Leningrad-Zagreb strain of mumps vaccine virus was grown on two different cell substrates viz. MRC-5 cells and Vero cells besides its original cell substrate i.e. Chicken Embryo Cells. Homogeneous virus pools prepared from each set of experiments were then lyophilized as per standard in-house protocol. Critical Quality Attributes (CQAs) such as the titer of the bulk vaccine and potency and stability of the lyophilized vaccine were then estimated using the CCID50 method to understand the lyophilization losses and thermal losses respectively in the vaccine. Another CQA viz. the genetic homogeneity of the vaccine was also tested using the single base extension method for identifying the nucleotides present at the three known locations of single nucleotide polymorphism (SNP). Comparison of CQA results across different cell substrates indicated encouraging results for Vero cell grown L-Zagreb virus compared to the MRC-5 cells grown L-Zagreb mumps virus. Significant improvement in productivity was also observed in the dynamic culture conditions compared to the static culture conditions. Progressive work in this research area can lead to development of a cGMP manufacturing process for mumps vaccine with easy scale up potential in future.

Waning immunity and re-emergence of measles and mumps in the vaccine era.

Vaccine-preventable diseases (VPD) including measles and mumps have been re-emerging in countries with sustained high vaccine coverage. For mumps, waning immunity has been recognized as a major contributor to recent outbreaks. Although unvaccinated individuals account for most cases in recent measles outbreaks, the role of immune waning remains unclear. Accumulating serological and epidemiological evidence suggests that natural immunity induced by infection may be more durable compared to vaccine-induced immunity. As the proportion of population immunity via vaccination gradually increases and boosting through natural exposures becomes rare, risk of outbreaks may increase. Mechanistic insights into the coupled immuno-epidemiological dynamics of waning and boosting will be important to understand optimal vaccination strategies to combat VPD re-emergence and achieve eradication.

An efficient, reproducible and accurate RT-qPCR based method to determine mumps specific neutralizing antibody.

INTRODUCTION: A resurgence of mumps among fully vaccinated adolescents and young adults globally has led to questions about the longevity of vaccine derived specific immunity. Unfortunately, the ideal serological correlate of immunity to mumps has yet to be identified. However, neutralising antibody titres in serum are used extensively as a surrogate marker of immunity to mumps. Conventional neutralisation tests are technically challenging, thus we developed and validated a high throughput, RT-qPCR microneutralisation (RT-qPCR-MN) method to determine serum neutralising antibody levels to mumps virus strains which avoids a number of the technical limitations of existing methods. METHODS: The qPCR-MN assays were thoroughly validated using human serum samples from patients with prior exposure to mumps infection or vaccination. RESULTS: Each sample of pooled sera neutralised virus at a constant rate and without significant changes when tested against genotype A (MuV-A) and G (MuV-G) mumps virus concentrations from 200 to 3200 TCID50. The within run and between run variation of the RT-qPCR-MN assays for both genotypes were less than 3 % and 9 % for low and high titre samples, respectively. The correlation between the focus reduction neutralisation test and RT-qPCR-MN was excellent for both MuV-G (r2 = 0.80, 95CI: 0.67-1.00, p < 0.0001) and MuV-A genotypes (r2 = 0.88, 95 %CI 0.69-1.00, p < 0.0001) endpoint determinations. CONCLUSIONS: We have developed a RT-qPCR MN assay for mumps virus that is simple, fast, scientifically objective and has high throughput. The assay can be used to provide key insights into the efficacy of mumps vaccination, to help explain the causes for the resurgence of mumps infection in vaccinated populations.

Outbreak of mumps in a student population with high vaccination coverage in China: time for two-dose vaccination.

In 2016, an outbreak of mumps occurred in a primary school in China with a student population having high vaccination coverage. An unmatched case-control study was performed to identify risk factors contributing to this outbreak, and a retrospective cohort study was conducted to evaluate the effectiveness of mumps-containing vaccine (MuCV). A total of 97 cases were identified during the outbreak, and the overall attack rate was 8.2%. Among students with confirmed vaccination status, 90% had received at least one dose of MuCV. Cases were more likely than non-cases to report taking the school bus during the epidemic period (adjusted OR = 2.3, 95% CI: 1.4-3.7). Vaccine effectiveness (VE) was higher for two-dose MuCV (76%, 95% CI:49â€"89%) than for one-dose MuCV (59%, 95% CI: 36â€"74%. The protection afforded by both one-dose and two-dose MuCV waned over time, from 82% among students vaccinated within 5 years to 41% among those vaccinated more than 10 years previously for one-dose VE, and from 90% to 25% over the same time period for two-dose VE. We found that outbreaks of mumps can occur in schools despite high coverage of one-dose MuCV vaccination. Although the VE of both two-dose and one-dose MuCV wanes over time, the overall VE for two-dose MuCV was superior than that of one-dose MuCV. Therefore, a two-dose MuCV schedule through routine services is likely needed in order to control mumps epidemics in China.

Humoral immunity to mumps in a highly vaccinated population in Taiwan.

BACKGROUND: A resurgence of mumps was noted recently and outbreaks were increasingly reported in populations with high vaccine coverage. We aimed to evaluate the seroprevalence to mumps in Taiwan, where a two-dose childhood mumps-containing vaccine program, with a high coverage rate, had been implemented for >20 years. METHODS: The anti-mumps IgG was determined in 3552 participants of all ages in Taiwan. The age-specific seropositivity rates were calculated and the sociodemographic variables associated with the seronegative sera were analyzed with a logistic regression method. RESULTS: The overall seroprevalence to mumps was 71%, with a higher rate in adults ≥19 years old than in the pediatric population <19 years old (80.4% versus 62.0%, P < 0.0001). In participants aged 2-20 years, who had been given at least one mumps-containing vaccine, the seropositivity fluctuated across different age subgroups and the lowest rate (36.8%) occurred in the 17-18 years age group. The multivariate analysis identified age within 17-18 years (adjusted odds ratio [aOR] 8.598, 95% confidence interval [CI] 2.990-24.722, P < 0.0001), within 19-20 years (aOR 5.076, 95% CI 1.702-15.133, P = 0.0080), and being a resident of the suburban area of northern Taiwan (aOR 1.089, 95% CI 0.823-1.414, P = 0.0008) as independent factors associated with an increased risk of seronegative sera. CONCLUSION: The seropositivity to mumps was unexpectedly low in highly vaccinated generations, and with a significant geographical discrepancy in Taiwan, which may have been responsible for the sustained reports of mumps cases in Taiwan.

Immunogenicity and Safety of an F-Genotype Attenuated Mumps Vaccine in Healthy 8- to 24-Month-Old Children.

Background: Mumps vaccine immunizations have reduced the incidence of this disease. With the variation of mumps circulating strain, novel vaccine strains are always important. Methods: A 2-center parallel, randomized, double-blind noninferiority trial was performed to compare an F-genotype attenuated mumps vaccine (SP strain) to the A-genotype vaccine (S-79, Jeryl-Lynn strain) in 1080 healthy children aged 8-24 months in Hubei, China. Results: Participants were randomly assigned to receive a high or low dose of the SP or S79 vaccine and then assessed clinically at 30 minutes and 1-28 days postinoculation. No differences in local or systemic reactivity were observed. A similar incidence of severe adverse events associated with the vaccine was observed in the high-dose group and the positive control group. Based on throat swab collections, no viral shedding was present at the 4th and 10th days in any group. Neutralizing and hemagglutination-inhibiting antibody assays with the F- or A-genotype strains showed similar trends in geometric mean titers in the high-dose SP and S79 groups. Increased cytotoxic T lymphocyte responses were observed in all groups. Conclusions: The F-genotype attenuated mumps vaccine is safe, offers immunogenicity against a homologous virus, and is noninferior to the A-genotype vaccine in 8- to 24-month-old children.

Differences in antigenic sites and other functional regions between genotype A and G mumps virus surface proteins.

The surface proteins of the mumps virus, the fusion protein (F) and haemagglutinin-neuraminidase (HN), are key factors in mumps pathogenesis and are important targets for the immune response during mumps virus infection. We compared the predicted amino acid sequences of the F and HN genes from Dutch mumps virus samples from the pre-vaccine era (1957-1982) with mumps virus genotype G strains (from 2004 onwards). Genotype G is the most frequently detected mumps genotype in recent outbreaks in vaccinated communities, especially in Western Europe, the USA and Japan. Amino acid differences between the Jeryl Lynn vaccine strains (genotype A) and genotype G strains were predominantly located in known B-cell epitopes and in N-linked glycosylation sites on the HN protein. There were eight variable amino acid positions specific to genotype A or genotype G sequences in five known B-cell epitopes of the HN protein. These differences may account for the reported antigenic differences between Jeryl Lynn and genotype G strains. We also found amino acid differences in and near sites on the HN protein that have been reported to play a role in mumps virus pathogenesis. These differences may contribute to the occurrence of genotype G outbreaks in vaccinated communities.

Assessment of one-dose mumps-containing vaccine effectiveness on wild-type genotype F mumps viruses circulating in mainland China.

To clarify the protective effect of one-dose mumps-containing vaccines (MuCV) in mainland China, the antigenic variations of HN gene and cross-neutralization capacities between MuCV and wild type genotype F MuVs were studied. In total, 70 HN gene sequences of genotype F MuV representative strains obtained from 2001 to 2015, two types of MuCV strains, 139 pairs of pre- and post-vaccination serum samples from infants receiving one dose of MuCV vaccination were analyzed. Genotype-specific amino acid variations were observed in the potential antigenic epitopes between MuCV and wild-type genotype F MuVs circulating in mainland China. The mumps neutralization antibody titers induced by one-dose MuCV were found to be generally low. Moreover, significant differences in neutralization titers were observed between vaccine and wild-type strains. It could be concluded that one-dose MuCV had a cross-protective effect against the wild-type genotype F MuVs, but its effectiveness was limited, which might be caused by insufficient doses of MuCV vaccination and the genotype-specific antigenic differences between vaccine and wild-type MuVs as well. In addition, a poor linear correlation between mumps-specific IgG concentrations and neutralization titers was observed in this study, indicating the concentration of MuV-specific IgG could not fully reflect the neutralizing antibody titer in serum. Therefore, it is highly recommended to provide a second dose of MuCV to preschool children to increase MuV neutralizing antibody titers and use MuV cross-neutralization test as preferred tool for assessment of mumps-containing vaccine effectiveness on wild-type MuVs. This is the first report to assess the effectiveness of one-dose Chinese MuCV against wild-type genotype F MuVs, which would be benefit for the development of mumps vaccination strategy.

Enhanced immunity in intradermal vaccination by novel hollow microneedles.

BACKGROUND: The intradermal (ID) route for vaccination represents an effective alternative to subcutaneous (SC)/intramuscular administration to induce protective immunity. However, a critical issue associated with ID vaccination is the precise delivery of solution in the upper dermis, which ensures enhanced immunity. METHODS: We fabricated a hollow microneedle unit made of poly-glycolic acid by injection molding and bonding, and created a dedicated prototype injector. To ensure ID delivery of solution, the injected site was macroscopically and microscopically examined. Serum immunoglobulin G antibody production was measured by enzyme immunoassay and compared in groups of rats following either ID delivery with microneedles or SC administration with a 27-G stainless needle of graded vaccine doses. RESULTS: The unit used a tandem array of six microneedles, each with a side delivery hole, and a conduit inside for solution. Microneedles installed in the injector punctured the skin with the aid of a spring. Injection of solution formed a wheal due to ID distribution. Histologically, a wedge-shaped skin defect in the upper skin corresponded to each puncture site. Antibody titers following vaccinations on days 1 and 8 were significantly higher with ID injection than with SC delivery on day 15 and every 7 days thereafter until day 36 with mumps vaccination, and until day 36 with varicella vaccination. CONCLUSIONS: The microneedle unit presented here delivered solution intradermally without any difficulty and evoked antibody responses against viruses even with the reduced vaccine volume. Our findings confirm promising results of ID delivery as an immunogenic option to enhance vaccination efficacy.

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.

Assessment of mumps-containing vaccine effectiveness during an outbreak: Importance to introduce the 2-dose schedule for China.

INTRODUCTION: China has used 3 different mumps-containing vaccines (MuCV) since 1990: monovalent mumps vaccine, measles-mumps (MM) vaccine, and measles-mumps-rubella (MMR) vaccine, and one dose MuCV (using MMR at 18 months) has been included in the EPI since 2007. MuCV effectiveness has been of concern following large-scale mumps outbreaks. In 2015, an outbreak of mumps occurred in a primary school, which allow us assess vaccine effectiveness of different MuCVs. METHOD: All children in the school were studied as a retrospective cohort. Vaccination histories and case information were obtained from vaccination records and clinic/hospital logs. Parental questionnaires were used to confirm students' illnesses and calculate attack rate (AR). VE was assessed using the formula, VE = (AR in unvaccinated students- AR in the vaccinated students) / (AR in unvaccinated students). VEs of different type of MuCV were compared. RESULTS: In total, 283 students were identified as clinical mumps among the 2370 students, and 1908 students were included for MuCV VE assessment. 213 (including 21 [8.9%] patients) were 2-dose MuCV recipients (AR: 9.9%), 1165 (including 123 [51.9%] patients) were 1-dose recipients (AR: 10.6%), and 530 (including 93 [39.2%] patients) were unvaccinated (AR: 17.5%). VE was 44% for 2 doses and 40% for one dose. For one-MuCV-dose students, estimated mumps VE was 63% for vaccinated within 3 years (between vaccination and this outbreak); 50% for vaccinated within 3 to 5 years; and 34% for vaccinated more than 5 years. Comparing VE by vaccine type and 5-year interval since vaccination, VE for MMR was 60%, which was consistently higher than VE for monovalent mumps vaccine (22%) and MM (2%). CONCLUSION: This outbreak was associated with low and declining 1-dose MuCV effectiveness. China's immunization program should evaluate the potential of a 2-dose MMR schedule to adequately control mumps.

Emergent lineages of mumps virus suggest the need for a polyvalent vaccine.

Mumps outbreaks among vaccinated patients have become increasingly common in recent years. While there are multiple conditions driving this re-emergence, convention has suggested that these outbreaks are associated with waning immunity rather than vaccine escape. Molecular evidence from both the ongoing American and Dutch outbreaks in conjunction with recent structural biology studies challenge this convention, and suggest that emergent lineages of mumps virus exhibit key differences in antigenic epitopes from the vaccine strain employed: Jeryl-Lynn 5. The American and Dutch 2016-2017 outbreak lineages were examined using computational biology through the lens of diversity in immunogenic epitopes. Findings are discussed and the laboratory evidence indicating neutralization of heterologous mumps strains by serum from vaccinated individuals is reviewed. Taken together, it is concluded that the number of heterologous epitopes occurring in mumps virus in conjunction with waning immunity is facilitating small outbreaks in vaccinated patients, and that consideration of a polyvalent mumps vaccine is warranted.

The Effect of Various Stabilizers on Preserving Immunogenicity of Lyophilized Mumps Vaccines.

BACKGROUND: Chemical stabilizers are added to live attenuated vaccines for enhancing the virus stability. The aim of this study was to evaluate the effect of various stabilizers on preserving immunogenicity of lyophilized mumps vaccines. STUDY DESIGN: An experimental study. METHODS: Three mumps vaccines with different formulations were inoculated to three groups of Guinea pigs. Sterile water was injected to eight Guinea pigs as a control group. Blood samples were collected before inoculation and on 14, 28 and 42 d after vaccine injection. Mumps antibodies in the sera were measured using hemagglutination inhibition assay (HAI). RESULTS: All three formulated mumps vaccines induced antibody in Guinea pigs after two weeks. Formulation 1 containing trehalose dihydrate and formulation 2 comprised human serum albumin stimulated antibodies in the higher level than Razi routine formulation. CONCLUSIONS: Various stabilizers have different preservation potencies that differently affect immune response against virus. More stable and more immunogenic vaccines can be produced using stabilizers containing trehalose dihydrate.

An outbreak of mumps with genetic strain variation in a highly vaccinated student population in Scotland.

An outbreak of mumps within a student population in Scotland was investigated to assess the effect of previous vaccination on infection and clinical presentation, and any genotypic variation. Of the 341 cases, 79% were aged 18-24. Vaccination status was available for 278 cases of whom 84% had received at least one dose of mumps containing vaccine and 62% had received two. The complication rate was 5·3% (mainly orchitis), and 1·2% were admitted to hospital. Genetic sequencing of mumps virus isolated from cases across Scotland classified 97% of the samples as genotype G. Two distinct clusters of genotype G were identified, one circulating before the outbreak and the other thereafter, suggesting the virus that caused this outbreak was genetically different from the previously circulating virus. Whilst the poor vaccine effectiveness we found may be due to waning immunity over time, a contributing factor may be that the current mumps vaccine is less effective against some genotypes. Although the general benefits of the measles-mumps-rubella (MMR) vaccine should continue to be promoted, there may be value in reassessing the UK vaccination schedule and the current mumps component of the MMR vaccine.

Immunogenicity of mumps virus vaccine candidates matching circulating genotypes in the United States and China.

Mumps virus (MuV) causes acute infection in humans with characteristic swelling of the parotid gland. While vaccination has greatly reduced the incidence of MuV infection, there have been multiple large outbreaks of mumps virus (MuV) in highly vaccinated populations. The most common vaccine strain, Jeryl Lynn, belongs to genotype A, which is no longer a circulating genotype. We have developed two vaccine candidates that match the circulating genotypes in the United States (genotype G) and China (genotype F). We found that there was a significant decrease in the ability of the Jeryl Lynn vaccine to produce neutralizing antibody responses to non-matched viruses, when compared to either of our vaccine candidates. Our data suggests that an updated vaccine may allow for better immunity against the circulating MuV genotypes G and F.

Cellular and humoral immunity after vaccination or natural mumps infection.

BACKGROUND: This study measured cell-mediated immunity (CMI) and serum antibody to clarify the basis of breakthrough after vaccination and reinfection after mumps. METHODS: From a pool of 54 college students, 17 seronegative subjects and 14 subjects with intermediate level of antibodies against mumps were vaccinated with a monovalent mumps vaccine, and CMI was assessed using interferon-γ release assay. RESULTS: CMI positivity according to pre-existing antibody level, defined as titer <2.0 index units, negative; 2.0-3.9 index units, intermediate; and ≥4.0 index units, positive, was 8/17 (47.1%), 9/14 (64.3%) and 19/23 (82.6%) before vaccination, respectively. Of the 17 seronegative subjects, seven (41.2%) had a history of vaccination and/or natural infection, four (57.1%) of whom were CMI positive or intermediate. Ten (71%) of 14 subjects with intermediate antibody level had a history of vaccination or natural infection, eight (80%) of whom were CMI positive or intermediate. After vaccination the interferon (IFN)-γ and antibody titers increased significantly, but seven (41.2%) of the 17 seronegative subjects and 13 (92.9%) of the 14 intermediate-level subjects tested positive for both antibody and CMI. In a comparison of the natural infection group (confirmed as IgG seropositive and/or CMI positive without vaccination) versus the vaccination group, IgG antibody titer (mean ± SD) was 14.4 ± 8.0 versus 3.6 ± 2.4 index units (P < 0.01) and IFN-γ was 122.7 ± 90.0 pg/mL versus 59.5 ± 37.8 pg/mL (P > 0.05), respectively. CONCLUSION: Vaccination or even natural mumps infection did not always induce both cellular and humoral immunity.