Mumps Outbreak at a University and Recommendation for a Third Dose of Measles-Mumps-Rubella Vaccine - Illinois, 2015-2016

Characteristics of reported mumps cases in the United States: 2018-2023

BACKGROUND

This paper highlights recent clinical complications of mumps reported in the United States and summarizes appropriate confirmatory testing for mumps, encouraging vigilance for mumps disease, an endemic vaccine-preventable illness.

METHODS

Surveillance data from jurisdictions reporting confirmed and probable cases of mumps in the United States were descriptively analyzed to assess epidemiologic trends from January 1, 2018 - December 31, 2023. Data were reported to the National Notifiable Disease Surveillance System and the Epidemiology and Laboratory Capacity Project O. Cases were classified according to the Council of State and Territorial Epidemiologists 2011 mumps case definition.

RESULTS

From 2018-2023, United States health departments reported 8,006 confirmed and probable mumps cases to the National Notifiable Disease Surveillance System, of which 85.4% occurred during January 1, 2018-April 4, 2020 and 14.6% during April 5, 2020-December 31, 2023. The incidence of mumps was highest among those aged 18-24 years during 2018-2020 (maximum of 4.54 cases per 100,000 persons in 2019), and highest among those aged 1-4 years during 2021-2023 (maximum 0.67 per 100,000 persons in 2023). Incidence among all age groups during 2021-2023 remained below levels during 2018-2020. Fewer than 12% of mumps cases were confirmed during 2021-2023, compared to >50% during 2018-2019.

CONCLUSIONS

Although incidence has declined since the COVID-19 pandemic, these surveillance data highlight that mumps remains endemic in the United States. Therefore, maintaining high MMR vaccination coverage is essential to prevent future vaccine-preventable outbreaks and minimize severe complications from infection.

Measles, mumps, rubella and varicella antibodies among international and domestic university students

BACKGROUND

Vaccine-preventable infections are generally well controlled in Australia. However, gaps in immunity can lead to outbreaks and are important to identify. Young adults are a highly mobile population and a potential source of imported infections. We aimed to evaluate anti- measles, mumps, rubella and varicella (MMR&V) IgG seroprevalence and explore factors relating to antibody seropositivity.

METHODS

A cross-sectional online survey was conducted among students from a large Australian university to collect demographic, vaccination, infection and travel characteristics. Blood samples were collected to measure MMR&V seroprevalence. Logistic regression was used to identify factors associated with seropositivity.

RESULTS

Among 804 university students, seroprevalence (positive or equivocal) for measles was 82.3% (95% CI 79.6-84.8%), mumps 79.5% (95% CI 76.7-82.3%), rubella 91.5% (95% CI 89.6-93.5%) and varicella 86.2% (95% CI 84.1-88.8%), with 452 (56.2%, 95% CI 52.8-59.6) seropositive to all four viruses. Varicella seropositivity was highest in the older birth cohort (born 1988-1991). Measles seropositivity was higher for international students compared to domestic students. Among international students, mumps seroprevalence was significantly lower than measles and rubella seroprevalence. International travel in the previous 12 months was reported by 63.1% of students, but only 18.2% of travellers reported seeking pre-travel health advice prior to most recent international travel.

CONCLUSIONS

Overall, this study suggests immunity to MMR&V is sub-optimal. We found the university student population to be highly mobile and unlikely to seek pre-travel advice; thus, they are a potential source of infection importation. The implementation of university immunization policies could address the gaps identified and our findings can inform the development of targeted vaccination campaigns.

Genome-wide determinants of cellular immune responses to mumps vaccine

BACKGROUND

We have previously described genetic polymorphisms in candidate genes that are associated with inter-individual variations in antibody responses to mumps vaccination. To expand upon our previous work, we performed a genome-wide association study (GWAS) to discover host genetic variants associated with mumps vaccine-induced cellular immune responses.

METHODS

We performed a GWAS of mumps-specific immune response outcomes (11 secreted cytokines/chemokines) in a cohort of 1,406 subjects.

RESULTS

Among the 11 cytokine/chemokines we studied, four (IFN-γ, IL-2, IL-1β, and TNFα) demonstrated GWAS signals reaching genome-wide significance (p < 5 × 10-8). A genomic region (encoding Sialic acid-binding immunoglobulin-type lectins/SIGLEC) located on chromosome 19q13 (p < 5 × 10-8) was associated with both IL-1β and TNFα responses. The SIGLEC5/SIGLEC14 region contained 11 statistically significant single nucleotide polymorphisms (SNPs), including the intronic SIGLEC5 rs872629 (p = 1.3E-11) and rs1106476 (p = 1.32E-11) whose alternate alleles were significantly associated with decreased levels of mumps-specific IL-1β (rs872629, p = 1.77E-09; rs1106476, p = 1.78E-09) and TNFα (rs872629, p = 1.3E-11; rs1106476, p = 1.32E-11) production.

CONCLUSIONS

Our results suggest that SNPs in the SIGLEC5/SIGLEC14 genes play a role in cellular and inflammatory immune responses to mumps vaccination. These findings motivate further research into the functional roles of SIGLEC genes in the regulation of mumps vaccine-induced immunity.

Trend of immunity against measles and varicella zoster virus in healthcare workers in Korea

OBJECTIVE

To examine the seroprevalence of measles and varicella zoster virus (VZV) among healthcare workers (HCW) and evaluate the concordance between self-reported history of previous disease or vaccination and seropositivity.

DESIGN

A seroprevalence study and survey.

SETTING

A university-affiliated tertiary care hospital.

PARTICIPANTS

All HCWs working in high-risk services in 2017 underwent serologic tests and survey; all new HCWs employed in the subsequent years, serologic tests only.

METHODS

A serologic study was conducted using chemiluminescence immunoassay (2017) or enzyme immunoassays (2018 and later). HCWs who underwent serological testing in 2017 completed a self-administered questionnaire on their history of infection and vaccination.

RESULTS

A total of 10,278 and 9607 HCWs underwent serologic tests for measles and VZV IgG, respectively, from 2017 to 2022. The overall seropositivity rates for measles and VZV were 78.1 % and 92.8 %, respectively. Measles seropositivity declined gradually from >90 % in the HCWs born in the 1960s to <80 % in those born in the 1990s. There was a significant difference in measles seropositivity between the birth cohorts (BCs) 1967-1984 and 1985-1999 (P < 0.001; odds ratio, 1.16; 95 % confidence interval, 1.14-1.18). The seropositivity for VZV was stable, at >90 % in all BCs. The self-reported vaccination history was not independently associated with seropositivity, and the negative predictive value of the survey was very low (9.6 % and 13.1 %, respectively).

CONCLUSIONS

Measles seropositivity showed a substantial decline among HCWs born in 1985 or later, while varicella seropositivity remained high. The self-reported vaccination history was not sufficiently reliable for screening HCWs.

Genome-Wide Determinants of Cellular Immune Responses to Mumps Vaccine

Background

We have previously described genetic polymorphisms in candidate genes that are associated with inter-individual variations in antibody responses to mumps vaccination. To expand upon our previous work, we performed a genome-wide association study (GWAS) to discover host genetic variants associated with mumps vaccine-induced cellular immune responses.

Methods

We performed a GWAS of mumps-specific immune response outcomes (11 secreted cytokines/chemokines) in a cohort of 1,406 subjects.

Results

Among the 11 cytokine/chemokines we studied, four (IFN-γ, IL-2, IL-1β, and TNFα) demonstrated GWAS signals reaching genome-wide significance (p<5 x 10 -8 ). A genomic region (encoding Sialic acid-binding immunoglobulin-type lectins/SIGLEC) located on chromosome 19q13 (p<5×10 -8 ) was associated with both IL-1β and TNFα responses. The SIGLEC5/SIGLEC14 region contained 11 statistically significant single nucleotide polymorphisms (SNPs), including the intronic SIGLEC5 rs872629 (p=1.3E-11) and rs1106476 (p=1.32E-11) whose alternate alleles were significantly associated with decreased levels of mumps-specific IL-1β (rs872629, p=1.77E-09; rs1106476, p=1.78E-09) and TNFα (rs872629, p=1.3E-11; rs1106476, p=1.32E-11) production.

Conclusions

Our results suggest that SNPs in the SIGLEC5/SIGLEC14 genes play a role in cellular and inflammatory immune responses to mumps vaccination. These findings motivate further research into the functional roles of SIGLEC genes in the regulation of mumps vaccine-induced immunity.

Epidemiological features and sociodemographic factors associated with mumps in mainland China from 2004 to 2018

BACKGROUND

Mumps is an acute infectious disease that spreads widely around the world. The aim of this study was to investigate the epidemiological features and sociodemographic factors associated with mumps in mainland China from 2004 to 2018.

METHODS

Incidence data for mumps during the period 2004-2018 were collected from the Public Health Sciences Data Center of China. Joinpoint regression analysis was performed to explore the trends of mumps. Space-time clustering analysis was conducted to spatial and temporal aggregation areas of mumps. A generalized linear model was used to explore sociodemographic factors associated with the incidence of mumps.

RESULTS

Average annual incidence of mumps was 21.44/100,000 in mainland China. It was increased dramatically during 2004-2012 (APC = 7.51, 95%CI: 2.28 to 13.00). After 2012, it remained stable, however, significantly increased in intermediately developed regions from 2015 to 2018 (APC = 25.84, 95%CI: 3.59 to 52.86). The first-level spatial and temporal aggregation areas were distributed in Xinjiang, Gansu, Qinghai, Ningxia and Shaanxi, Tibet, Sichuan, Yunnan, Chongqing, Guizhou, Guangxi, with gathering times from Jan 1, 2006 to Dec 31, 2012 (RR = 1.87, P < 0.001). The percentage of the population aged 0-14 years, number of health workers per capital, and number of passengers were found to be positively associated with the incidence of mumps.

CONCLUSIONS

Overall, after 2012, the incidence of mumps in mainland China remained stable. High-risk periods, clusters of regions and sociodemographic factors for mumps were identified, which will help the government develop disease- and location-specific interventive measures. This article is protected by copyright. All rights reserved.

Impact of vaccine effectiveness and coverage on preventing large mumps outbreaks on college campuses: Implications for vaccination strategy

Recent mumps outbreaks among highly vaccinated populations, including college students, have called into question the vaccine effectiveness (VE) of routine two-dose measles, mumps, and rubella (MMR2) immunization. We aimed to estimate the VE required for a novel vaccination strategy (e.g., MMR booster dose, novel vaccine) to prevent large mumps outbreaks on college campuses. Using mumps college outbreak data reported to the U.S. Centers for Disease Control and Prevention during 2016-2017, we estimated current MMR2 VE using the screening method and implemented a compartmental model of mumps transmission. We performed 2000 outbreak simulations, following introduction of an infectious person to a population of 10,000, over ranges of MMR2 vaccine coverage (VC) and VE (30.0-99.0%). We compared the impact of varying VC and VE on mumps and mumps orchitis case counts and determined VE thresholds that ensured < 5.0% and < 2.0% of the outbreak simulations exceeded 20 and 100 mumps cases. Median estimated MMR2 VE in reported mumps outbreaks was 60.5% and median reported MMR2 VC was 97.5%. Simulated mumps case count was more sensitive to changes in VE than in VC. The opposite was true for simulated mumps orchitis case count, though orchitis case count was small (mean <10 cases across simulations for VE near 60.5% and VC near 97.5%). At 97.5% VC, 73.1% and 78.2% VE were required for < 5.0% and < 2.0% of outbreaks, respectively, to exceed 100 mumps cases. Maintaining 97.5% VC, 82.4% and 85.9% VE were required for < 5.0% and < 2.0% of outbreaks, respectively, to exceed 20 cases. We conclude that maintaining current levels of MMR2 VC, a novel vaccination strategy aimed at reducing mumps transmission must achieve at least 73.1-85.9% VE among young adults to prevent large mumps outbreaks on college campuses.

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 in Vaccinated Children and Adolescents: 2007-2019

BACKGROUND

Despite a >99% reduction in US mumps cases after the introduction of mumps vaccine in 1967, outbreaks have occurred in schools and other settings involving vaccinated children and adolescents since 2006.

METHODS

We analyzed mumps cases reported by US health departments to the National Notifiable Diseases Surveillance System. We present the incidence and vaccination status of pediatric cases (age <18 years) during 2007-2019 and describe demographic, clinical, and vaccination characteristics of pediatric cases reported during the most recent resurgence in 2015-2019.

RESULTS

During 2007-2019, 9172 pediatric cases were reported, accounting for a median of 32% of all cases reported each year (range: 13%-59%). A median of 87% (range: 81%-94%) of pediatric patients each year had previously received ≥1 measles, mumps, and rubella (MMR) vaccine dose. During 2015-2019, of 5461 pediatric cases reported, only 2% of those with known import status (74%) were associated with international travel. One percent of patients had complications and 2% were hospitalized. Among patients aged ≥1 year with known vaccination status (72%), 74% of 1- to 4-year-olds had received ≥1 MMR dose and 86% of 5- to 17-year-olds had received ≥2 MMR doses. Since 2016, pediatric mumps cases have been reported in most US states each year (range: 38-45 states).

CONCLUSIONS

Since 2007, one-third of US reported mumps cases occurred in children and adolescents, the majority of whom were vaccinated. Clinicians should suspect mumps in patients with parotitis or mumps complications, regardless of age, travel history, and vaccination status.

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 outbreak among fully vaccinated school-age children and young adults, Portugal 2019/2020

On 16–17 January 2020, four suspected mumps cases were reported to the local Public Health Authorities with an epidemiological link to a local school and football club. Of 18 suspected cases identified, 14 were included in this study. Laboratory results confirmed mumps virus as the cause and further sequencing identified genotype G. Our findings highlight that even with a high MMR vaccine coverage, mumps outbreaks in children and young adults can occur. Since most of the cases had documented immunity for mumps, we hypothesise that waning immunity or discordant mumps virus strains are likely explanations for this outbreak.

Repeated introductions and intensive community transmission fueled a mumps virus outbreak in Washington State

In 2016/2017, Washington State experienced a mumps outbreak despite high childhood vaccination rates, with cases more frequently detected among school-aged children and members of the Marshallese community. We sequenced 166 mumps virus genomes collected in Washington and other US states, and traced mumps introductions and transmission within Washington. We uncover that mumps was introduced into Washington approximately 13 times, primarily from Arkansas, sparking multiple co-circulating transmission chains. Although age and vaccination status may have impacted transmission, our data set could not quantify their precise effects. Instead, the outbreak in Washington was overwhelmingly sustained by transmission within the Marshallese community. Our findings underscore the utility of genomic data to clarify epidemiologic factors driving transmission and pinpoint contact networks as critical for mumps transmission. These results imply that contact structures and historic disparities may leave populations at increased risk for respiratory virus disease even when a vaccine is effective and widely used.

The local stability of a modified multi-strain SIR model for emerging viral strains

We study a novel multi-strain SIR epidemic model with selective immunity by vaccination. A newer strain is made to emerge in the population when a preexisting strain has reached equilbrium. We assume that this newer strain does not exhibit cross-immunity with the original strain, hence those who are vaccinated and recovered from the original strain become susceptible to the newer strain. Recent events involving the COVID-19 virus shows that it is possible for a viral strain to emerge from a population at a time when the influenza virus, a well-known virus with a vaccine readily available, is active in a population. We solved for four different equilibrium points and investigated the conditions for existence and local stability. The reproduction number was also determined for the epidemiological model and found to be consistent with the local stability condition for the disease-free equilibrium.

Development of Improved Mumps Vaccine Candidates by Mutating Viral mRNA Cap Methyltransferase Sites in the Large Polymerase Protein

Although a live attenuated vaccine is available for controlling mumps virus (MuV), mumps still outbreaks frequently worldwide. The attenuated MuV vaccine strain S79 is widely used in mumps vaccination in China, but still with many shortcomings, among which the most prominent are the side effects and decreased immunity. Therefore, there is a need to further improve the safety and efficacy of the current MuV vaccine. In the present study, we further attenuated MuV S79 vaccine strain by inhibiting viral mRNA methyltransferase (MTase). We generated a panel of eight recombinant MuVs (rMuVs) carrying mutations in the MTase catalytic site or S-adenosylmethionine (SAM) binding site in the large (L) polymerase protein. These rMuVs are genetically stable and seven rMuVs are more attenuated in replication in cell culture and five rMuVs are more attenuated in replication in lungs of cotton rats compared with the parental vaccine strain S79. Importantly, cotton rats vaccinated with these seven rMuV mutants produced high levels of serum neutralizing antibodies and were completely protected against challenge with a wild-type MuV strain (genotype F). Therefore, our results demonstrate that alteration in the MTase catalytic site or SAM binding site in MuV L protein improves the safety or the immunogenicity of the MuV vaccine and thus mRNA cap MTase may be an effective target for the development of new vaccine candidates for MuV.

Identification and description of mumps cases in a non-outbreak setting and evaluation of the effectiveness of mumps-containing vaccines over time

Mumps outbreaks among previously vaccinated young adults raise concerns regarding waning vaccine immunity. This study identified, described and assessed the changing incidence of mumps cases following mumps-containing vaccination (MMR/MMRV) in a non-mumps outbreak setting. Potential cases between 1996 and 2018 were identified by the international classification of disease codes or by mumps laboratory test orders among Kaiser Permanente Northern California members. Medical charts were reviewed to confirm diagnoses, timing relative to vaccination and clinical characteristics. Among 474 potential cases, 257 (54.2%) were confirmed after chart review. A third of the cases were <10 years old at diagnosis and 48% were over 25 years. Most cases (92.2%) had parotitis and 5% of males had orchitis. Mumps rates decreased from 8.5 to 1.8/1,000,000 person-years as time since the second MMR/MMRV dose increased from <2 years to ≥10 years. Similarly, rates decreased from 16.3 to 3/1,000,000 person-years after at least 1 dose of MMR/MMRV. Mumps rates were higher among children aged ≤10 years compared with older age groups. In conclusion, in the context of a non-outbreak setting, this study suggests that waning of vaccine immunity to mumps appeared to have minimal clinical impact.

Australian mumps serosurvey 2012-2013: any cause for concern?

Objectives

To determine population-level immunity to mumps in Australia.

Methods

We tested randomly selected specimens from people aged 1-49 years using the Enzygnost anti-parotitis IgG enzyme immunoassay from an opportunistically collected serum bank in 2012-2013. Weighted estimates of the proportion seropositive and equivocal for mumps-specific IgG antibody were determined by age group and compared with two previous national serosurveys conducted in 2007-2008 and 1997-1998.

Results

Overall, 82.1% (95% CI 80.6-83.5%) of 2,729 specimens were positive or equivocal for mumps-specific IgG antibodies (71.1% positive [95% CI 69.4-72.9%]; 10.9% equivocal [95% CI 9.8-12.2%]). The proportion positive or equivocal was higher in 2012-2013 (82.1%) than in 2007-2008 (75.5%) and 1997-1998 (72.5%), but varied by age. The proportion positive or equivocal in 2012-2013 was above 80% for all age groups older than 1 year except for 30-34 year olds, corresponding to the 1978-1982 birth cohort previously identified as most likely to have missed out on a second MMR vaccine dose.

Conclusion

Seropositivity to mumps in 2012-2013 was well-maintained compared with previous serosurveys. Low mumps notifications over this period in Australia suggest an absence of community-based transmission of mumps infection in the general population, but recent outbreaks among Aboriginal adolescents and young adults in close-contact settings, despite high 2-dose MMR coverage, suggest that seroprotection may be insufficient in other similar settings in Australia.Seropositivity to mumps in 2012-2013 was well-maintained compared with previous serosurveys. Low mumps notifications over this period in Australia suggest an absence of community-based transmission of mumps infection in the general population, but recent outbreaks among Aboriginal adolescents and young adults in close-contact settings, despite high 2-dose MMR coverage, suggest that seroprotection may be insufficient in other similar settings in Australia.

Adverse Events Among Young Adults Following a Third Dose of Measles-Mumps-Rubella Vaccine

BACKGROUND

A third measles-mumps-rubella vaccine (MMR) dose (MMR3) is recommended in the United States for persons at increased risk for mumps during outbreaks. MMR3 is also likely given to persons who might have received 2 doses of MMR but lack documentation. Since MMR3 safety data are limited, we describe adverse events in persons receiving MMR3 in a nonoutbreak setting.

METHODS

Young adults with 2 documented MMR doses were administered MMR3. From 2 weeks before until 4 weeks after MMR3 receipt, participants reported daily on 11 solicited, common symptoms potentially associated with MMR. Weekly rate differences in post- vs prevaccination (baseline) were evaluated by Poisson regression. Baseline rates were subtracted from postvaccination rates of significantly different symptoms to estimate the number and percentage of participants with excess risk for symptoms post-MMR3. Descriptive analyses were performed for 3 postvaccination injection-site symptoms.

RESULTS

The 662 participants were aged 18-28 years (median = 20 years); 56% were women. Headache, joint problems, diarrhea, and lymphadenopathy rates were significantly higher postvaccination vs baseline. We estimate that 119 participants (18%) reported more symptoms after MMR3 than prevaccination. By symptom, 13%, 10%, 8%, and 6% experienced increased symptoms of headache, joint problems, diarrhea, and lymphadenopathy, respectively, after MMR3. The median onset was Days 3-6 postvaccination; the median duration was 1-2 days. One healthcare visit for a potential vaccination-related symptom (urticaria) was reported. Injection-site symptoms were reported by 163 participants (25%); the median duration was 1-2 days.

CONCLUSIONS

Reported systemic and local events were mild and transient. MMR3 is safe and tolerable among young adults.

The Importance of MMR Immunization in the United States

Despite the established safety and efficacy of the measles-mumps-rubella vaccine after almost 50 years of widespread use, the United States is encountering higher levels of measles and mumps disease than has occurred for years. Return of disease threatens the health of those who remain unimmunized by choice as well as those who are immunized appropriately but experience loss of vaccine-induced immunity. The solution to continued threats of illness caused by these untreatable but readily preventable diseases is compliance with recommendations for administration of the measles-mumps-rubella vaccine. Here we examine trends in the epidemiology of measles, mumps, and rubella in recent years and consider the consequences of loss of protective immunity within our country.

Recognizing Vaccine-Preventable Diseases and Managing Outbreaks

Outbreaks of vaccine-preventable diseases are becoming more common in the United States. Outbreaks of some diseases, such as measles, can be attributed to decreasing vaccination rates. Clinicians need to be aware of the vulnerabilities in their communities. Detection of an outbreak requires familiarity with signs, symptoms, and laboratory findings for these now unusual diseases. Clinicians also need to work with public health officials to identify, treat, and limit the spread of these infections. This article describes the populations most at risk from illnesses associated with sporadic outbreaks, with information on diagnosis, treatment, and ways to limit the spread of infection.

Assessing the Changes of Mumps Characteristics with Different Vaccination Strategies Using Surveillance Data: Importance to Introduce the 2-Dose Schedule in Quzhou of China

BACKGROUND

From 2005 to 2016, the prevention and control of mumps in China have undergone three stages of transition. These include the use of MuCV as a self-supported vaccine, the introduction of one-dose MMR to the Expanded Program on Immunization (EPI), and the administration of two-dose MuCV following supplementary immunization activities (SIAs) using MM. Here, using surveillance data, we assessed the epidemiology of mumps during the three stages.

METHODS

Children in Quzhou of China born from 2005 to 2016 and registered in the Zhejiang Provincial Immunization Information System (ZJIIS) were included. We analyzed the epidemic data and calculated incidence and MuCV coverage via birth cohorts.

RESULTS

The average incidence of mumps in 2005-2006, 2007-2010, and 2011-2016 was 51.57, 41.02, and 12.53 per 100,000 individuals, respectively. The highest incidence was in children aged 6-14 years from 2005-2016, of which the majority were school students (67.84%). Approximately 90% of the reported outbreaks occurred in school children (primary school/middle school). The seasonal characteristics of mumps were less obvious from 2011 to 2016. The coverage of one-dose MMR in the 2005 birth cohort was 71.38%. For the 2006-2010 birth cohort, the coverage of one-dose MuCV was 96.82% and the coverage of two-dose MuCV was 17.68%. The children born from 2011 to 2016 were only free vaccinated with MMR; the coverage of one-dose MuCV was 99.10%. The mumps incidence in the three birth cohorts significantly declined (X 2 = 805.90, P < 0.001 for trend). Except the children less than two years old, the mumps incidence for the children born from 2006 to 2010 was higher than that for the children born from 2011 to 2016.

CONCLUSION

The mumps incidence significantly declined following the introduction of one-dose MMR. The SIA using MM led to a rapid reduction of mumps cases. Therefore, we recommend a two-dose MuCV routine immunization schedule and improved vaccination coverage.

Long time persistence of antibodies against Mumps in fully MMR immunized young adults: an Italian retrospective cohort study

Protective levels of antibodies induced by the MMR vaccine have been shown to decline over time, but actually there is not a formal recommendation about the opportunity of testing immunized HCWs to investigate the persistence of anti-Mumps IgG. This study aims to evaluate the long-time immunogenicity of MMR vaccination in a sample of medical students and residents of the University of Bari who attended the Hygiene Department for the biological risk assessment (April 2014-June 2018). A strategy for the management of non-responder subjects has been experimented and described. Two thousand students and residents, with documented immunization status (two doses of MMR vaccine), have been tested. 120/2,000 (6%; 95%CI = 5.0–7.1%) subjects did not show anti-Mumps IgG. This percentage was similar among males and females. After a third MMR dose, we noted a seroconversion of 90% of seronegative participants. No serious adverse events were recorded. An important proportion of subjects immunized for MMR do not show an antibodies protective titer. The immunogenicity and the safety of the third dose seem confirmed by our data. Including the screening model described in the routine assessment of the biological risk of medical students and HCWs may be a winning strategy in preventing Mumps nosocomial infection.

Genetic characterization of mumps viruses associated with the resurgence of mumps in the United States: 2015-2017

Despite high coverage with measles, mumps, and rubella vaccine in the United States, outbreaks of mumps occur in close contact settings such as schools, colleges, and camps. Starting in late 2015, outbreaks were reported from several universities, and by the end of 2017, greater than 13,800 cases had been reported nation-wide. In 2013, the CDC and the Association of Public Health Laboratories contracted four Vaccine Preventable Diseases Reference Centers (VPD-RCs) to perform real-time reverse transcription PCR (RT-qPCR) to detect mumps RNA in clinical samples and to determine the genotype. Twelve genotypes of mumps virus are currently recognized by the World Health Organization, and the standard protocol for genotyping requires sequencing the entire gene coding for the small hydrophobic (SH) protein. Phylogenetic analysis of the 1862 mumps samples genotyped from 2015 through 2017 showed that the overall diversity of genotypes detected was low. Only 0.8 % of the sequences were identified as genotypes C, H, J, or K, and 0.5 % were identified as vaccine strains in genotypes A or N, while most sequences (98.7 %) were genotype G. The majority of the genotype G sequences could be included into one of two large groups with identical SH sequences. Within genotype G, a small number of phylogenetically significant outlier sequences were associated with epidemiologically distinct chains of transmission. These results demonstrate that molecular and epidemiologic data can be used to track transmission pathways of mumps virus; however, the limited diversity of the SH sequences may be insufficient for resolving transmission in all outbreaks.

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 outbreak and MMR IgG surveillance as a predictor for immunity in military trainees

In 2017, a mumps outbreak occurred in a barrack holding 249 service members. Suspected cases were evaluated with a combination of mumps IgG, IgM, viral culture, PCR and sequencing. Seven cases were diagnosed in febrile patients presenting with parotitis or orchitis. Mumps infection was confirmed by IgM or positive PCR with 5/7 cases having notable IgG levels before infection. Sequencing confirmed mumps genotype G strain. Serum from all 249 service members collected prior to the outbreak was withdrawn from the Department of Defense (DoD) Serum Repository and the IgG values of measles, mumps and rubella determined with 20.2%, 12.3% and 9.7% service members being seronegative, respectively. No specific IgG seronegativity combination predicted IgG marker levels to another virus within the same vaccine. This paper provides additional evidence that mumps serology is not a reliable surrogate for mumps immunity and that we need better laboratory correlates to confirm immunity.

Mumps Outbreak in a Highly Vaccinated University-Affiliated Setting Before and After a Measles-Mumps-Rubella Vaccination Campaign-Iowa, July 2015-May 2016

Background

In response to a mumps outbreak at the University of Iowa and surrounding community, university, state, and local health officials implemented a vaccination campaign targeting students <25 years of age with an additional dose of measles-mumps-rubella (MMR) vaccine. More than 4700 vaccine campaign doses were administered; 97% were documented third doses. We describe the epidemiology of the outbreak before and after the campaign, focusing on cases in university students.

Methods

Mumps cases were identified from reportable disease databases and university health system records. Detailed information on student cases was obtained from interviews, medical chart abstractions, university and state vaccination records, and state public health laboratory results. Pre- and postcampaign incidence among students, university faculty/staff, and community members <25 vs ≥25 years old were compared using Fisher exact test. Multivariable regression modeling was performed to identify variables associated with a positive mumps polymerase chain reaction test.

Results

Of 453 cases in the county, 301 (66%) occurred in university students. Student cases were primarily undergraduates (90%) and highly vaccinated (86% had 2 MMR doses, and 12% had 3 MMR doses). Fewer cases occurred in students after the campaign (75 [25%]) than before (226 [75%]). Cases in the target group (students <25 years of age) declined 9% postcampaign (P=.01). A positive mumps polymerase chain reaction test was associated with the presence of parotitis and early sample collection, and inversely associated with recent receipt of MMR vaccine.

Conclusions

Following a large additional dose MMR vaccination campaign, fewer mumps cases occurred overall and in the target population.

Decreased humoral immunity to mumps in young adults immunized with MMR vaccine in childhood

In the past decade, multiple mumps outbreaks have occurred in the United States, primarily in close-contact, high-density settings such as colleges, with a high attack rate among young adults, many of whom had the recommended 2 doses of mumps-measles-rubella (MMR) vaccine. Waning humoral immunity and the circulation of divergent wild-type mumps strains have been proposed as contributing factors to mumps resurgence. Blood samples from 71 healthy 18- to 23-year-old college students living in a non-outbreak area were assayed for antibodies and memory B cells (MBCs) to mumps, measles, and rubella. Seroprevalence rates of mumps, measles, and rubella determined by IgG enzyme-linked immunosorbent assay (ELISA) were 93, 93, and 100%, respectively. The index standard ratio indicated that the concentration of IgG was significantly lower for mumps than rubella. High IgG avidity to mumps Enders strain was detected in sera of 59/71 participants who had sufficient IgG levels. The frequency of circulating mumps-specific MBCs was 5 to 10 times lower than measles and rubella, and 10% of the participants had no detectable MBCs to mumps. Geometric mean neutralizing antibody titers (GMTs) by plaque reduction neutralization to the predominant circulating wild-type mumps strain (genotype G) were 6-fold lower than the GMTs against the Jeryl Lynn vaccine strain (genotype A). The majority of the participants (80%) received their second MMR vaccine ≥10 years prior to study participation. Additional efforts are needed to fully characterize B and T cell immune responses to mumps vaccine and to develop strategies to improve the quality and durability of vaccine-induced immunity.

Epidemiological Characteristics and Spatiotemporal Analysis of Mumps from 2004 to 2018 in Chongqing, China

Mumps vaccines have been widely used in recent years, but frequent mumps outbreaks and re-emergence around the world have not stopped. Mumps still remains a serious public health problem with a high incidence in China. The status of mumps epidemics in Chongqing, the largest city in China, is still unclear. This study aimed to investigate the epidemiological and spatiotemporal characteristics of mumps and to provide a scientific basis for formulating effective strategies for its prevention and control. Surveillance data of mumps in Chongqing from January 2004 to December 2018 were collected from the National Notifiable Diseases Reporting Information System. A descriptive analysis was conducted to understand the epidemiological characteristics. Hot spots and spatiotemporal patterns were identified by performing a spatial autocorrelation analysis, a purely spatial scan, and a spatiotemporal scan at the county level based on geographic information systems. A total of 895,429 mumps cases were reported in Chongqing, with an annual average incidence of 36.34 per 100,000. The yearly incidence of mumps decreased markedly from 2004 to 2007, increased sharply from 2007 to 2011, and then tapered with a two-year cyclical peak after 2011. The onset of mumps showed an obvious bimodal seasonal distribution, with a higher peak of mumps observed from April to July of each year. Children aged 5–9 years old, males, and students were the prime high-risk groups. The spatial distribution of mumps did not exhibit significant global autocorrelation in most years, but local indicators of spatial autocorrelation and scan statistics detected high-incidence clusters which were mainly located in the midwestern, western, northeastern, and southwestern parts of Chongqing. The aggregation time frame detected by the purely temporal scan was between March 2009 and July 2013. The incidence of mumps in Chongqing from 2004 to 2018 featured significant spatial heterogeneity and spatiotemporal clustering. The findings of this study might assist public health agencies to develop real-time space monitoring, especially in the clustering regions and at peak periods; to improve immunization strategies for long-term prevention; and to deploy health resources reasonably.

Viral mumps: Increasing occurrences in the vaccinated population

Before the introduction of the vaccine, mumps was the most common salivary gland disease and was one of the most common infectious diseases in children globally. Following the introduction of the mumps vaccine in 1967, the disease was almost nonexistent in the United States and was only found to occur in nonvaccinated patients, and even then, it did not present in epidemic portions because of the extent of vaccination in the population at large. Beginning in the early 2000s, viral mumps began to present itself in vaccinated populations, and currently, outbreaks are continuing to increase in number. This article presents information on the various outbreaks, a review of the virus and the disease, including symptoms and comorbidities, and new recommendations for management. Dental practitioners should be aware of the increasing incidence and prevalence of this disease, be able to recognize it, and make appropriate referrals for management.

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.

Mumps in a highly vaccinated Marshallese community in Arkansas, USA: an outbreak report

BACKGROUND

During 2000-15, Arkansas Department of Health, Little Rock, AR, USA, investigated between one and six cases of mumps each year. From Aug 5, 2016, to Aug 5, 2017, the department received notification of more than 4000 suspected mumps cases in the second largest outbreak in the USA in the past 30 years.

METHODS

Arkansas Department of Health investigated all reported cases of mumps to ascertain exposure, travel, and vaccination histories and identify close contacts. Cases were classified as confirmed if the patient had laboratory confirmation of mumps virus or probable if they had clinical symptoms and either a positive serological test or a known epidemiological link to a confirmed case.

FINDINGS

2954 cases of mumps related to the outbreak were identified during the outbreak period: 1665 (56%) were laboratory confirmed, 1676 (57%) were in children aged 5-17 years, and 1692 (57%) were in Marshallese people. Among the 1676 school-aged cases, 1536 (92%) had previously received at least two doses of a vaccine containing the mumps virus. Although 19 cases of orchitis were reported, severe complications were not identified. Unusual occurrences, such as recurrent parotitis and prolonged viral shedding, were observed mostly in Marshallese individuals. Viral samples were characterised as genotype G.

INTERPRETATION

This large-scale outbreak, primarily affecting a marginalised community with intense household crowding, highlights the need for coordinated, interdisciplinary, and non-traditional outbreak responses. This outbreak raises questions about mumps vaccine effectiveness and potential waning immunity.

FUNDING

Council of State and Territorial Epidemiologists and US Centers for Disease Control and Prevention.

Investigation and management of a large community mumps outbreak among young adults in Toronto, Canada, January 2017-February 2018

Background

In 2017, a mumps outbreak was identified in a cohort of 18-34 year olds in Toronto, Canada.

Objective

To describe a large community mumps outbreak in an urban centre from January 2017 to February 2018 among young adults.

Methods

A broad range of interventions were implemented in an attempt to reach the target audience; including case and contact management, vaccination clinics at schools and clinicians' offices, school exclusions, bar inspections, traditional communication strategies (including health care provider updates and posters) and newer communication strategies (including three sequential social media campaigns).

Results

A total of 143 cases of mumps were identified. Although cases' ages ranged from three to 72 years, most (76%) were 18-34 year olds, many of whom had frequented bars and local food establishments in downtown Toronto. 84% (n=120) of the cases were community-acquired. Only 16% (n=23) of the cases reported exposures in schools and post-secondary school institutions. Of those, 39% (n=56) of cases had an unknown vaccination history; 34% (n=49) were either not vaccinated or partially vaccinated with one dose of measles-mumps-rubella vaccine; and 27% (n=38) had received the recommended two doses of mumps vaccine. Determining vaccination status was a challenge, in part due to the lack of a registry. Vaccination was recommended when subjects were known to have had fewer than two doses of vaccine or had an unknown vaccination status. A social media campaign, emphasizing the risk of social activities if not protected from the mumps, yielded over 500,000 impressions from Facebook and Twitter messages and ads and an impressive engagement rate of between 1% and 10x%.

Conclusion

This was the largest mumps outbreak in Toronto in over 20 years. Among young adults, ongoing social media and traditional communication campaigns can contribute to the control of community mumps outbreaks. Encouraging vaccine uptake is desirable, but without a vaccine registry it is difficult to assess vaccination coverage among adults. Susceptible cohorts of young adults who were not adequately vaccinated pose a risk for future outbreaks. Given that almost 30% of the mumps cases were fully vaccinated with two doses of mumps-containing vaccine, even two doses may not provide complete protection.

Emerging Topics in Vaccine Therapeutics for Adolescents and Adults: An Update for Immunizing Pharmacists

Vaccine therapeutics and the practice of immunization provision are ever-changing. As pharmacy-based immunization services continue to flourish in the United States, more and more patients are requesting both routine and travel vaccines in community pharmacies. However, vaccine recommendations from the Centers for Disease Control and Prevention/Advisory Committee on Immunization Practices (CDC/ACIP) can sometimes differ from product-specific US Food and Drug Administration (FDA)-indicated uses. In addition, changes in vaccine schedules, product availability, and disease outbreaks can present immunizing pharmacists with scenarios requiring a high level of clinical judgment. Thus, it is of paramount importance that all immunizing pharmacists maintain competency in the most recent evidence in vaccine therapeutics, as well as practice standards for vaccine provision and administration. This review provides an update of the most recent literature surrounding emerging topics in adolescent and adult immunizations—highlighting influential studies and recent developments in the prevention of herpes zoster, human papillomavirus (HPV), measles, mumps, rubella (MMR), meningococcal disease, tetanus, diphtheria, and pertussis. Key concepts discussed include the emergence of the new recombinant zoster vaccine (RZV), meningococcal vaccine product selection, MMR revaccination during disease outbreaks, tetanus vaccine product selection, and duration of pertussis immunity with vaccination.

Cost of Public Health Response and Outbreak Control With a Third Dose of Measles-Mumps-Rubella Vaccine During a University Mumps Outbreak-Iowa, 2015-2016

Background

The United States is experiencing mumps outbreaks in settings with high 2-dose measles-mumps-rubella (MMR) vaccine coverage, mainly universities. The economic impact of mumps outbreaks on public health systems is largely unknown. During a 2015-2016 mumps outbreak at the University of Iowa, we estimated the cost of public health response that included a third dose of MMR vaccine.

Methods

Data on activities performed, personnel hours spent, MMR vaccine doses administered, miles traveled, hourly earnings, and unitary costs were collected using a customized data tool. These data were then used to calculate associated costs.

Results

Approximately 6300 hours of personnel time were required from state and local public health institutions and the university, including for vaccination and laboratory work. Among activities demanding time were case/contact investigation (36%), response planning/coordination (20%), and specimen testing and report preparation (13% each). A total of 4736 MMR doses were administered and 1920 miles traveled. The total cost was >$649 000, roughly equally distributed between standard outbreak control activities and third-dose MMR vaccination (55% and 45%, respectively).

Conclusions

Public health response to the mumps outbreak at the University of Iowa required important amounts of personnel time and other resources. Associated costs were sizable enough to affect other public health activities.

Development and Use of an Endpoint Titration Assay To Characterize Mumps IgG Avidity following Measles, Mumps, and Rubella Vaccination and Wild-Type Mumps Infection

Waning mumps IgG antibody and incomplete IgG avidity maturation may increase susceptibility to mumps virus infection in some vaccinees. To measure mumps IgG avidity, serum specimens serially diluted to the endpoint were incubated on a commercial mumps-specific IgG enzyme immunoassay and treated with the protein denaturant diethylamine (60 mM, pH 10). End titer avidity indices (etAIs [percent ratio of detected diethylamine-resistant IgG at endpoint]) were calculated. Unpaired serum specimens (n = 108) from 15-month-old children living in a low-incidence setting were collected 1 month and 2 years after the first measles, mumps, and rubella vaccine dose (MMR1) and tested for mumps avidity. Per the receiver operating characteristic curve, the avidity assay is accurate (area under the curve, 0.994; 95% confidence interval [CI], 0.956 to 1.000), 96.5% sensitive (95% CI, 87.9 to 99.6%), and 92.2% specific (95% CI, 81.1 to 97.8%) at an etAI of 30%. When 9 sets of paired serum specimens collected 1 to 60 months post-MMR1 were tested for mumps and measles IgG avidity using comparable methods, the mumps etAI increased from 11% to 40 to 60% in 6 months. From 6 to 60 months, avidity was sustained at a mean etAI of 50% (95% CI, 46 to 54%), significantly lower (P  < 0.0001) than the mean measles etAI of 80% (95% CI, 74 to 86%). Mean etAIs in children 2 years post-MMR1 (n = 51), unvaccinated adults with distant mumps disease (n = 29), and confirmed mumps cases (n = 23) were 54, 62, and 57%, respectively. A mumps-specific endpoint avidity assay was developed and validated, and mumps avidity was determined to be generally sustained at etAIs of 40 to 60%, reaching etAIs of >80% in some individuals.IMPORTANCE Numerous outbreaks of mumps have occurred in the United States among two-dose measles-mumps-rubella (MMR)-vaccinated populations since 2006. The avidity of mumps-specific IgG antibodies may affect susceptibility to mumps virus infection in some vaccinated individuals. To accurately measure mumps avidity, we developed and validated a mumps-specific IgG avidity assay that determines avidity at the endpoint titer of serially diluted serum specimens, providing results that are independent of IgG concentration. At low antibody titers, endpoint methods are considered more accurate than methods that determine avidity at a single dilution. We determined that 6 months after the first MMR dose, mumps IgG avidity is high and generally sustained at avidity indices of 40 to 60%, reaching values of >80% in some individuals. Additionally, 4% (4/103) of individuals had avidity indices of ≤30% (low avidity) 2 years after vaccination. Inadequate mumps avidity maturation may be one factor influencing susceptibility to mumps virus infection among previously vaccinated or naturally infected individuals.

Progress and challenges for the Japanese immunization program: Beyond the "vaccine gap"

The Japanese immunization program has made considerable recent progress. The introduction of several new vaccines, especially foreign-produced vaccines, and the inclusion of important new vaccines in the National Immunization Program (NIP) are closing the "vaccine gap", i.e., the delay in the Japanese immunization program relative to programs in other developed countries. Major progress in the Japanese immunization program since 2014 includes (1) elimination of measles in March 2015, (2) introduction of a varicella vaccine as a routine immunization in the NIP in October 2015, and (3) introduction of hepatitis B virus vaccines as routine immunizations in the NIP in October 2016. Despite these promising developments, important issues remain. First, the government withdrew the active recommendation for human papilloma virus vaccines temporarily in 2013. The withdrawal has continued and unresolved despite new scientific evidence confirming the safety of these vaccines. Second, a few important voluntary vaccines, including vaccines for mumps and rotavirus, have not been included in the NIP since their introduction to Japan. Finally, there are concerns related to a shortage of mandatory domestic vaccines, which was caused by a natural disaster in the area where a vaccine-producing factory was located. Additionally, the manufacturer included unauthorized additives in some vaccine products with falsifying the production-process records. To avoid problems related to vaccine shortages, essential vaccines need to be stockpiled, and the future vaccine needs for children should to be discussed. New initiatives must continue to close the vaccine gap, as this will protect children living in Japan from vaccine-preventable diseases.

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.

Diagnostic Yield of Laboratory Methods and Value of Viral Genotyping during an Outbreak of Mumps in a Partially Vaccinated Population in British Columbia, Canada

Mumps remains endemic in North America despite routine use of the measles, mumps, and rubella (MMR) vaccine. In 2016, an outbreak of mumps in British Columbia, Canada, provided an opportunity to determine the diagnostic utility of laboratory testing methods. Specimens from patients with clinical mumps were tested for infection using a commercial enzyme-linked immunosorbent assay (ELISA) for antibody detection and an in-house reverse transcriptase PCR (RT-PCR) targeting viral fusion and small hydrophobic (SH) genes. Viral genotyping was performed by SH gene sequencing. Laboratory data was linked with epidemiologic case data. Of the 139 confirmed cases, 94 (68%) had reported or documented history of MMR vaccination. Specimens were typically collected 1 day (for buccal and IgM tests) or 2 days (for urine tests) after symptom onset. Most confirmed cases (69%) were confirmed by buccal swab RT-PCR. Among cases tested by multiple methods, the percent positivity for buccal swab RT-PCR was 90% (96/107) compared to 43% (30/69) for both IgM ELISA and urine RT-PCR. Mumps IgM detection was higher in confirmed cases with no history of vaccination than in those with history (64% versus 34%, P = 0.02). The outbreak strain was identified as genotype G related to MuVi/Sheffield.GBR/1.05 but with conserved variations in five nucleotides within the SH gene that allowed linkage of geographically distinct cases. In conclusion, RT-PCR of buccal specimens had the highest diagnostic yield during a mumps outbreak in a partially vaccinated population. To optimize mumps diagnostic potential, clinicians should collect specimens depending on when the patient presents for care and their immunization history.

Vaccine waning and mumps re-emergence in the United States

After decades of declining mumps incidence amid widespread vaccination, the United States and other developed countries have experienced a resurgence in mumps cases over the last decade. Outbreaks affecting vaccinated individuals and communities with high vaccine coverage have prompted concerns about the effectiveness of the live attenuated vaccine currently in use. It is unclear whether immune protection wanes or whether the vaccine protects inadequately against currently circulating mumps virus lineages. Synthesizing data from six studies of mumps vaccine effectiveness, we estimated that vaccine-derived immune protection against mumps wanes on average 27 years (95% confidence interval, 16 to 51 years) after vaccination. After accounting for this waning, we found no evidence that the emergence of heterologous virus genotypes contributed to changes in vaccine effectiveness over time. A mathematical model of mumps transmission confirmed the central role of waning immunity to the vaccine in the re-emergence of mumps cases. Outbreaks from 2006 to the present among young adults, and outbreaks in the late 1980s and early 1990s among adolescents, aligned with peaks in mumps susceptibility of these age groups predicted to be due to loss of vaccine-derived protection. In contrast, evolution of mumps virus strains escaping immune pressure would be expected to cause a higher proportion of cases among children, not adolescents and young adults as observed. Routine use of a third vaccine dose at 18 years of age, or booster dosing throughout adulthood, may be a strategy to prevent mumps re-emergence and should be assessed in clinical trials.

Characterization of Vaccination Policies for Attendance and Employment at Day/Summer Camps in New York State

INTRODUCTION

New York state requires day/summer camps to keep immunization records for all enrolled campers and strongly recommends requiring vaccination for all campers and staff. The objective of this study was to characterize immunization requirements/recommendations for children/adolescents enrolled in and staff employed at day/summer camps in New York state.

METHODS

An electronic hyperlink to a 9-question survey instrument was distributed via e-mail to 178 day/summer camps located in New York state cities with a population size greater than 100 000 people. A follow-up telephone survey was offered to nonresponders. The survey instrument included questions pertaining to vaccination documentation policies for campers/staff and the specific vaccines that the camp required/recommended. Fisher's exact and Chi-square tests were used to analyze categorical data.

RESULTS

Sixty-five day/summer camps responded to the survey (36.5% response rate): 48 (73.8%) and 23 (41.8%) camps indicated having a policy/procedure for documenting vaccinations for campers and staff, respectively. Camps that had a policy/procedure for campers were more likely to have a policy/procedure for staff (P = .0007). Age-appropriate vaccinations that were required/recommended for campers by at least 80% of camps included: measles, mumps, and rubella (MMR), diphtheria, tetanus, and pertussis (DTaP), hepatitis B, inactivated/oral poliovirus (IPV/OPV), Haemophilus influenzae type b (Hib), and varicella. Age-appropriate vaccinations that were required/recommended for staff by at least 80% of camps included: DTaP, hepatitis B, IPV/OPV, MMR, meningococcus, varicella, Hib, and tetanus, diphtheria, and pertussis (Tdap).

CONCLUSION

Vaccination policies at day/summer camps in New York state appear to be suboptimal. Educational outreach may encourage camps to strengthen their immunization policies, which may reduce the transmission of vaccine-preventable diseases.