Mumps outbreaks, especially in adolescents and young adults, have been reported in the Czech Republic. The aim of the presented study was to determine the seroprevalence of specific IgG antibodies against mumps in the adult population of the Czech Republic. The study was designed as a multicenter serological survey of adults aged 18 years and over. Specific IgG antibodies against mumps were detected in blood samples using an enzyme-linked immunosorbent assay (ELISA). A total of 1,911 serum samples were examined. The overall seropositivity reached 55.3%. In individual age groups, the highest seropositivity 63% (63.5-65.2%) was recorded in adults aged 40 years and over; the lowest seropositivity was found in adults aged 18-29 years (27.4%). The difference in seropositivity rate between the 18-29 years age group and the 40 years and over age groups was statistically significant (p < 0.001). Only the 18-29 years age group included both vaccinated and unvaccinated (born in the pre-vaccine era) individuals. In vaccinated individuals, seropositivity was reported in only 19.1% of persons; in unvaccinated individuals, seropositivity reached 48.2%. Our results demonstrate the long-term persistence of antibodies following natural infection and the decrease in seropositivity that occurs after vaccination over time. This immunity waning may account for the higher susceptibility of adolescents and young adults to mumps. Therefore, the current vaccination program in the Czech Republic could be considered as less effective. It will be modified with the shifting of the second dose of vaccine from two years of age to the preschool age.

• Keywords
• Czech Republic, adults, antibodies, mumps, seroprevalence, vaccination program,
• MeSH
• Adult MeSH
• Disease Outbreaks prevention & control   MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Immunization Programs methods   MeSH
• Mumps blood   immunology   prevention & control   MeSH
• Antibodies, Viral blood   immunology   MeSH
• Surveys and Questionnaires MeSH
• Aged MeSH
• Seroepidemiologic Studies MeSH
• Measles immunology   prevention & control   MeSH
• Measles-Mumps-Rubella Vaccine immunology   MeSH
• Vaccination methods   MeSH
• Mumps virus immunology   MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Czech Republic MeSH
• Names of Substances
• Antibodies, Viral MeSH
• Measles-Mumps-Rubella Vaccine MeSH

BACKGROUND: In the Czech Republic, two-dose immunization against mumps achieves 98% coverage. The routine reporting detects mumps cases, clinical complications, and hospital admissions in unvaccinated but also in vaccinated individuals. Using surveillance data of patients with mumps we assessed the effectiveness of mumps vaccination on mumps clinical complications and hospitalization need. We also investigated the effect of the time since immunization. METHODS: We analysed data on incident mumps cases reported to the Czech national surveillance system in 2007-2012. Using a logistic regression model with adjustment for age, sex, year of onset, and the administrative region, the association between vaccination and the most frequent mumps complications and hospitalization was evaluated. The adjusted odds ratios (ORa) for mumps complications were compared between the vaccinated and non-vaccinated groups, reflecting the vaccine effectiveness (VEa) computed as VEa = (1-ORa) × 100. We estimated the risk of mumps complications by the time from vaccination. RESULTS: From total of 9663 mumps analysed cases 5600 (58%) occurred in males. The mean age at the disease onset was 17.3, median 16 years. Ninety percent of the study patients had no complications, while 1.6% developed meningitis, 0.2% encephalitis, and 0.6% pancreatitis. Mumps orchitis occurred in 659 (11.8%) male cases. In total, 1192 (12.3%) patients required hospitalization. Two doses of vaccine received by 81.8% cases significantly reduced the risk of hospitalization: ORa 0.29 (95% CI: 0.24, 0.35). Two doses showed statistically significant VEa 64% (95% CI: 46, 79) for meningitis, 93% (95% CI: 66, 98) for encephalitis in all cases, and 72% (95% CI: 64, 78) for orchitis in males. Vaccine effectiveness for orchitis declined from 81 to 74% and 56% in the most affected age groups 10-14, 15-19, and 20-24 years, respectively. Among 7850 two-dose recipients, the rate of complications rose from below 1 to 16% in categories up to 6 years and 24 and more years after the second dose, respectively. CONCLUSIONS: This study demonstrates a significant preventive effect of two-dose vaccination against mumps complications (orchitis, meningitis, or encephalitis) and hospitalization for mumps. The risk of complications increases with time interval from vaccination. Teenagers and young adults were the most affected age groups.

• Keywords
• Hospitalization, Mumps, Mumps complications, Orchitis, Surveillance, Vaccination,
• MeSH
• Time Factors MeSH
• Child MeSH
• Adult MeSH
• Encephalitis epidemiology   prevention & control   MeSH
• Hospitalization statistics & numerical data   MeSH
• Infant MeSH
• Middle Aged MeSH
• Humans MeSH
• Meningitis epidemiology   prevention & control   MeSH
• Adolescent MeSH
• Young Adult MeSH
• Infant, Newborn MeSH
• Immunization Schedule MeSH
• Orchitis epidemiology   prevention & control   MeSH
• Child, Preschool MeSH
• Mumps complications   epidemiology   prevention & control   MeSH
• Risk MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Population Surveillance * MeSH
• Mumps Vaccine administration & dosage   MeSH
• Vaccination statistics & numerical data   MeSH
• Check Tag
• Child MeSH
• Adult MeSH
• Infant MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Male MeSH
• Infant, Newborn MeSH
• Child, Preschool MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Czech Republic epidemiology   MeSH
• Names of Substances
• Mumps Vaccine MeSH

Mumps vaccines are live attenuated viruses. They are known to vary in effectiveness, degree of attenuation and adverse event profile. However, the underlying reasons are poorly understood. We studied two closely related mumps vaccines which originate from the same attenuated Jeryl Lynn-5 strain but have different efficacies. Jeryl Lynn-Canine Kidney (JL-CK), produced on primary canine kidney cells, is less effective than RIT4385, which is produced on chicken embryo fibroblasts. JL-CK and RIT4385 could be distinguished by a number of in vitro and in vivo properties. JL-CK produced heterogeneous, generally smaller plaques than RIT4385, but gave 100-fold higher titres when grown in cells and showed a higher degree of hydrocephalus formation in neonatal rat brains. Sanger sequencing of JL-CK identified 14 regions of heterogeneity throughout the genome. Plaque purification of JL-CK demonstrated the presence of five different Jeryl Lynn-5 variants encompassing the 14 mutations. One JL-CK mutation was associated with a small plaque phenotype, the effects of the others in vitro or in vivo were less clear. Only 4% of the JL-CK population corresponded to the parental Jeryl Lynn-5 strain. Next generation sequencing of JL-CK and virus before and after growth in cell lines or neonatal rat brains showed that propagation in vitro or in vivo altered the population dramatically. Our findings indicate that growth of JL-CK in primary canine kidney cells resulted in the selection of a mixture of mumps virus variants that have different biological properties compared to the parent Jeryl Lynn-5 virus. We also report three previously unknown heterogenic regions within the N gene of the RIT4385 vaccine.

• Keywords
• Deep sequencing, Jeryl Lynn, Mumps virus, Neurovirulence, Vaccines,
• MeSH
• Epithelial Cells MeSH
• Technology, Pharmaceutical methods   MeSH
• Hydrocephalus pathology   virology   MeSH
• Rats MeSH
• Virus Cultivation methods   MeSH
• Cells, Cultured MeSH
• Chick Embryo MeSH
• Disease Models, Animal MeSH
• Animals, Newborn MeSH
• Viral Plaque Assay MeSH
• Population Dynamics MeSH
• Mumps Vaccine administration & dosage   immunology   MeSH
• Viral Load MeSH
• Virulence MeSH
• Mumps virus growth & development   immunology   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Chick Embryo MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Names of Substances
• Mumps Vaccine MeSH