Effectiveness of 13-valent pneumococcal conjugate vaccine for prevention of invasive pneumococcal disease among children in the United States between 2010 and 2019: An indirect cohort study.

BACKGROUND: A U.S. case-control study (2010-2014) demonstrated vaccine effectiveness (VE) for ≥ 1 dose of the thirteen-valent pneumococcal conjugate vaccine (PCV13) against vaccine-type (VT) invasive pneumococcal disease (IPD) at 86 %; however, it lacked statistical power to examine VE by number of doses and against individual serotypes. METHODS: We used the indirect cohort method to estimate PCV13 VE against VT-IPD among children aged < 5 years in the United States from May 1, 2010 through December 31, 2019 using cases from CDC's Active Bacterial Core surveillance, including cases enrolled in a matched case-control study (2010-2014). Cases and controls were defined as individuals with VT-IPD and non-PCV13-type-IPD (NVT-IPD), respectively. We estimated absolute VE using the adjusted odds ratio of prior PCV13 receipt (1-aOR x 100 %). RESULTS: Among 1,161 IPD cases, 223 (19.2 %) were VT cases and 938 (80.8 %) were NVT controls. Of those, 108 cases (48.4 %; 108/223) and 600 controls (64.0 %; 600/938) had received > 3 PCV13 doses; 23 cases (17.6 %) and 15 controls (2.4 %) had received no PCV doses. VE ≥ 3 PCV13 doses against VT-IPD was 90.2 % (95 % Confidence Interval75.4-96.1 %), respectively. Among the most commonly circulating VT-IPD serotypes, VE of ≥ 3 PCV13 doses was 86.8 % (73.7-93.3 %), 50.2 % (28.4-80.5 %), and 93.8 % (69.8-98.8 %) against serotypes 19A, 3, and 19F, respectively. CONCLUSIONS: At least three doses of PCV13 continue to be effective in preventing VT-IPD among children aged < 5 years in the US. PCV13 was protective against serotypes 19A and 19F IPD; protection against serotype 3 IPD did not reach statistical significance.

JYNNEOS™ effectiveness as post-exposure prophylaxis against mpox: Challenges using real-world outbreak data.

BACKGROUND: JYNNEOSTM vaccine has been used as post-exposure prophylaxis (PEP) during a mpox outbreak in New York City (NYC). Data on effectiveness are limited. METHODS: Effectiveness of a single dose of JYNNEOSTM vaccine administered subcutaneously ≤ 14 days as PEP for preventing mpox disease was assessed among individuals exposed to case-patients from May 22, 2022-August 24, 2022. Individuals were evaluated for mpox through 21 days post-exposure. An observational study was conducted emulating a sequence of nested "target" randomized trials starting each day after exposure. Results were adjusted for exposure risk and race/ethnicity. Analyses were conducted separately based on last (PEPL) and first (PEPF) exposure date. We evaluated the potential to overestimate PEP effectiveness when using conventional analytic methods due to exposed individuals developing illness before they can obtain PEP (immortal time bias) compared to the target trial. RESULTS: Median time from last exposure to symptom onset (incubation period) among cases that did not receive PEPL was 7 days (range 1-16). Time to PEPL receipt was 7 days (range 0-14). Among 549 individuals, adjusted PEPL and PEPF effectiveness was 19 % (95 % Confidence Interval [CI], -54 % to 57 %) and -7% (95 % CI, -144 % to 53 %) using the target trial emulation, respectively, and 78 % (95 % CI, 50 % to 91 %) and 73 % (95 % CI, 31 % to 91 %) using conventional analysis. CONCLUSIONS: Determining PEP effectiveness using real-world data during an outbreak is challenging. Time to PEP in NYC coupled with the observed incubation period resulted in overestimated PEP effectiveness using a conventional method. The target trial emulation, while yielding wide confidence intervals due to small sample size, avoided immortal time bias. While results from these evaluations cannot be used as reliable estimates of PEP effectiveness, we present important methodologic considerations for future evaluations.

Pfizer-BioNTech Coronavirus Disease 2019 Vaccine Effectiveness Against Severe Acute Respiratory Syndrome Coronavirus 2 Infection Among Long-term Care Facility Staff With and Without Prior Infection in New York City, January-June 2021.

BACKGROUND: Evidence is accumulating of coronavirus disease 2019 (COVID-19) vaccine effectiveness among persons with prior severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. METHODS: We evaluated the effect against incident SARS-CoV-2 infection of (1) prior infection without vaccination, (2) vaccination (2 doses of Pfizer-BioNTech COVID-19 vaccine) without prior infection, and (3) vaccination after prior infection, all compared with unvaccinated persons without prior infection. We included long-term care facility staff in New York City aged <65 years with weekly SARS-CoV-2 testing from 21 January to 5 June 2021. Test results were obtained from state-mandated laboratory reporting. Vaccination status was obtained from the Citywide Immunization Registry. Cox proportional hazards models adjusted for confounding with inverse probability of treatment weights. RESULTS: Compared with unvaccinated persons without prior infection, incident SARS-CoV-2 infection risk was lower in all groups: 54.6% (95% confidence interval, 38.0%-66.8%) lower among unvaccinated, previously infected persons; 80.0% (67.6%-87.7%) lower among fully vaccinated persons without prior infection; and 82.4% (70.8%-89.3%) lower among persons fully vaccinated after prior infection. CONCLUSIONS: Two doses of Pfizer-BioNTech COVID-19 vaccine reduced SARS-CoV-2 infection risk by ≥80% and, for those with prior infection, increased protection from prior infection alone. These findings support recommendations that all eligible persons, regardless of prior infection, be vaccinated against COVID-19.

Maintenance of Measles Elimination Status in the United States for 20 Years Despite Increasing Challenges.

BACKGROUND: Measles elimination (interruption of endemic measles virus transmission) in the United States was declared in 2000; however, the number of cases and outbreaks have increased in recent years. We characterized the epidemiology of measles outbreaks and measles transmission patterns after elimination to identify potential gaps in the US measles control program. METHODS: We analyzed national measles notification data from 1 January 2001 to 31 December 2019. We defined measles infection clusters as single cases (isolated cases not linked to additional cases), 2-case clusters, or outbreaks with ≥3 linked cases. We calculated the effective reproduction number (R) to assess changes in transmissibility and reviewed molecular epidemiology data. RESULTS: During 2001-2019, a total of 3873 measles cases, including 747 international importations, were reported in the United States; 29% of importations were associated with outbreaks. Among 871 clusters, 69% were single cases and 72% had no spread. Larger and longer clusters were reported since 2013, including 7 outbreaks with >50 cases lasting >2 months, 5 of which occurred in known underimmunized, close-knit communities. No measles lineage circulated in a single transmission chain for >12 months. Higher estimates of R were noted in recent years, although R remained below the epidemic threshold of 1. CONCLUSIONS: Current epidemiology continues to support the interruption of endemic measles virus transmission in the United States. However, larger and longer outbreaks in recent postelimination years and emerging trends of increased transmission in underimmunized communities emphasize the need for targeted approaches to close existing immunity gaps and maintain measles elimination.

Measles infection in persons with secondary vaccine failure, New York City, 2018-19.

A large measles outbreak in New York City, which included cases among vaccinated persons and adults presumed to be immune, provided the opportunity to better understand vaccine failure and the potential impact on measles transmission. Immunoglobulin G (IgG) avidity can distinguish primary (low avidity IgG, indicating no evidence of prior immunity) versus secondary vaccine failure (high avidity IgG, indicating prior immune response and waning antibody). Measles IgG avidity was measured on samples from 62 persons: avidity was high in 53 (16 vaccinated and 37 with unknown vaccination history) and low in 9 (1 recently vaccinated and 8 with unknown vaccination history). Secondary transmission from 2 persons with high-avidity IgG results occurred. These findings illustrate that in settings of sustained measles elimination, measles infection and transmission can occur in persons with secondary vaccine failure, underscoring the need to maintain a high index of suspicion for measles during an outbreak despite prior or presumed prior vaccination.

Trends in Hepatitis B Surveillance Among Pregnant Women in New York City, 1998-2015.

OBJECTIVE: Infants born to women with hepatitis B virus (HBV) infection are at high risk for chronic HBV infection and premature death. We examined epidemiologic trends among women with HBV infection who gave birth in New York City (NYC) to inform public health prevention activities. METHODS: We obtained data on HBV-infected women residing and giving birth in NYC during 1998-2015 from the NYC Perinatal HBV Prevention Program. We obtained citywide birth data from the NYC Office of Vital Statistics. We calculated the incidence of births to HBV-infected women per 100 000 live births and stratified by maternal race, birthplace, and age. We calculated annual percentage change (APC) in incidence of births to HBV-infected women by using joinpoint regression. RESULTS: Of 29 896 HBV-infected women included in the study, 28 195 (94.3%) were non-US-born, of whom 16 600 (58.9%) were born in China. Overall incidence of births to HBV-infected women per 100 000 live births increased from 1156 in 1998 to 1573 in 2006 (APC = 3.1%; P < .001) but declined to 1329 in 2015 (APC = -1.4%; P = .02). Incidence among US-born women declined from 1998 to 2015 (330 to 84; APC = -7.3%; P < .001) and among non-US-born women increased from 1998 to 2007 (1877 to 2864; APC = 3.6%; P < .001) but not thereafter. Incidence among women born in China increased from 1998 to 2006 (13 275 to 16 480; APC = 1.8%; P = .02) but decreased to 12 631 through 2015 (APC = -3.3%; P < .001). CONCLUSIONS: The incidence of births to HBV-infected women in NYC declined significantly among US-born women but not among non-US-born women, highlighting the need for successful vaccination programs worldwide.

Effect of Policy Change to Require Laboratory Reporting With Pregnancy Indicated for Syphilis and Hepatitis B Virus Infection, New York City, January 2013-June 2018.

OBJECTIVES: We evaluated the impact of a 2014 New York City health code change requiring laboratories to indicate if a patient is pregnant or probably pregnant in the electronic laboratory report (ELR) when reporting syphilis and hepatitis B virus (HBV) cases to the New York City Department of Health and Mental Hygiene (DOHMH). METHODS: We calculated the number of pregnant persons with syphilis or HBV infection reported to DOHMH from January 1, 2013, through June 30, 2018. We compared the proportion in which the first report to DOHMH was an ELR with pregnancy indicated before and after the policy change. We calculated time between first ELR with pregnancy indicated and subsequent reporting by a method other than ELR and the proportion of cases in which ELR with pregnancy indicated was the only report source. RESULTS: A total of 552 new syphilis and 8414 HBV-infected cases were reported to DOHMH. From January 2013-June 2014 (pre-change) to January 2017-June 2018 (post-change), the proportion of cases in which ELR with pregnancy indicated was the first report to DOHMH increased significantly (14.7% [23/156] to 46.2% [80/173] for syphilis; 8.0% [200/2498] to 45.3% [851/1879] for HBV infection [P < .001]). Median time between first ELR with pregnancy indicated and subsequent reporting by a method other than ELR was 9.0 days for syphilis and 51.0 days for HBV infection. ELR with pregnancy indicated was the only report for 43.1% (238/552) of syphilis cases and 23.4% (1452/6200) of HBV cases during the study period. CONCLUSION: Including pregnancy status with ELR can increase the ability of public health departments to conduct timely interventions to prevent mother-to-child transmission.

Use of Capture-Recapture Analysis to Assess Reporting Completeness of Births to Hepatitis B-Positive Women in New York City, 2013-2014.

OBJECTIVES: The New York City (NYC) Department of Health and Mental Hygiene (DOHMH) depends on reporting by health care facilities and laboratories for disease surveillance. Our objective was to evaluate the completeness of DOHMH surveillance to identify births to hepatitis B virus (HBV)-positive women to prevent perinatal transmission. METHODS: We identified infants born to HBV-positive women by matching mothers of all infants born in NYC during May 1, 2013-May 1, 2014, identified from the Citywide Immunization Registry (CIR) to persons with HBV-positive laboratory reports in the Electronic Laboratory Reporting (ELR) system. We then matched infants born to mothers identified in the CIR/ELR match to infants born to HBV-positive women from the DOHMH perinatal HBV surveillance database. We performed capture-recapture analysis to evaluate completeness of DOHMH case identification. We compared the proportion of infants born to HBV-positive mothers reported to DOHMH with the proportion of infants identified only through the CIR/ELR match for receipt of postexposure prophylaxis (PEP) and completion of the HBV vaccination series and post-vaccination serology testing. RESULTS: Of 1662 infants identified from the CIR/ELR match and 1554 infants in the DOHMH database, 1493 infants matched. Of 169 infants only in the CIR/ELR data set, 55 were born to HBV-positive women residing in NYC. Sixty-one infants were only in the DOHMH database. An estimated 2 infants were not identified by either method. The CIR/ELR match increased infant identification by 3.5%, from 1554 to 1609 infants. The proportion of infants who received PEP was significantly higher among infants whose mothers were reported to DOHMH (vs not reported to DOHMH). PRACTICAL IMPLICATIONS: Use of the CIR/ELR match may further improve DOHMH identification of infants born to HBV-positive women and receipt of infant PEP.

Consequences of Undervaccination - Measles Outbreak, New York City, 2018-2019.

BACKGROUND: Measles was declared eliminated in the United States in 2000, but the risk of outbreaks owing to international importations remains. An outbreak of measles in New York City began when one unvaccinated child returned home from Israel with measles; onset of rash occurred on September 30, 2018, 9 days after the child returned home. METHODS: We investigated suspected cases of measles by conducting interviews, reviewing medical and immunization records, identifying exposed persons, and performing diagnostic testing. Measles-mumps-rubella (MMR) vaccine (given as either MMR or measles-mumps-rubella-varicella vaccine and collectively referred to as MMR vaccine) uptake was monitored with the use of the Citywide Immunization Registry. The total direct cost to the New York City Department of Health and Mental Hygiene was calculated. RESULTS: A total of 649 cases of measles were confirmed, with onsets of rash occurring between September 30, 2018, and July 15, 2019. A majority of the patients (93.4%) were part of the Orthodox Jewish community, and 473 of the patients (72.9%) resided in the Williamsburg area of Brooklyn, New York. The median age was 3 years; 81.2% of the patients were 18 years of age or younger, and 85.8% of the patients with a known vaccination history were unvaccinated. Serious complications included pneumonia (in 37 patients [5.7%]) and hospitalization (in 49 patients [7.6%]); among the patients who were hospitalized, 20 (40.8%) were admitted to an intensive care unit. As a result of efforts to promote vaccination, the percentage of children in Williamsburg who received at least one dose of MMR vaccine increased from 79.5% to 91.1% among children 12 to 59 months of age. As of September 9, 2019, a total of 559 staff members at the Department of Health and Mental Hygiene (7% of the agency) had been involved in the measles response. The cost of the Department of Health and Mental Hygiene response was $8.4 million. CONCLUSIONS: Importation of measles and vaccination delays among young children led to an outbreak of measles in New York City. The outbreak response was resource intensive and caused serious illness, particularly among unvaccinated children.

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.

Public Health Consequences of a 2013 Measles Outbreak in New York City.

Importance: Internationally imported cases of measles into the United States can lead to outbreaks requiring extensive and rapid control measures. Importation of measles from an unvaccinated adolescent in 2013 led to what has been the largest outbreak of measles in New York City, New York, since 1992. Objective: To describe the epidemiology and public health burden in terms of resources and cost of the 2013 measles outbreak in New York City. Design, Setting, and Participants: This epidemiologic assessment and cost analysis conducted between August 15, 2013, and August 5, 2014, examined all outbreak-associated cases of measles among persons residing in New York City in 2013. Exposures: Measles virus. Main Outcomes and Measures: Numbers of measles cases and contacts. Total personnel time and total direct cost to the New York City Department of Health and Mental Hygiene (DOHMH), calculated as the sum of inputs (supplies and materials, equipment, and logistics) and personnel time (salary and fringe benefits). Results: Between March 13, 2013, and June 9, 2013, 58 persons in New York City with a median age of 3 years (range, 0-32 years) were identified as having measles. Among these individuals, 45 (78%) were at least 12 months old and were unvaccinated owing to parental refusal or intentional delay. Only 28 individuals (48%) visited a medical health care professional who suspected measles and reported the case to the DOHMH at the initial clinical suspicion. Many case patients were not immediately placed into airborne isolation, resulting in exposures in 11 health care facilities. In total, 3351 exposed contacts were identified. Total direct costs to the New York City DOHMH were $394 448, and a total of 10 054 hours were consumed responding to and controlling the outbreak. Conclusions and Relevance: Vaccine refusals and delays appeared to have propagated a large outbreak following importation of measles into the United States. Prompt recognition of measles along with rapid implementation of airborne isolation of individuals suspected of measles infection in health care facilities and timely reporting to public health agencies may avoid large numbers of exposures. The response and containment of measles outbreaks are resource intensive.

Non-mumps Viral Parotitis During the 2014-2015 Influenza Season in the United States.

Background: During the 2014-2015 US influenza season, 320 cases of non-mumps parotitis (NMP) among residents of 21 states were reported to the Centers for Disease Control and Prevention (CDC). We conducted an epidemiologic and laboratory investigation to determine viral etiologies and clinical features of NMP during this unusually large occurrence. Methods: NMP was defined as acute parotitis or other salivary gland swelling of >2 days duration in a person with a mumps- negative laboratory result. Using a standardized questionnaire, we collected demographic and clinical information. Buccal samples were tested at the CDC for selected viruses, including mumps, influenza, human parainfluenza viruses (HPIVs) 1-4, adenoviruses, cytomegalovirus, Epstein-Barr virus (EBV), herpes simplex viruses (HSVs) 1 and 2, and human herpes viruses (HHVs) 6A and 6B. Results: Among the 320 patients, 65% were male, median age was 14.5 years (range, 0-90), and 67% reported unilateral parotitis. Commonly reported symptoms included sore throat (55%) and fever (48%). Viruses were detected in 210 (71%) of 294 NMP patients with adequate samples for testing, ≥2 viruses were detected in 37 samples, and 248 total virus detections were made among all samples. These included 156 influenza A(H3N2), 42 HHV6B, 32 EBV, 8 HPIV2, 2 HPIV3, 3 adenovirus, 4 HSV-1, and 1 HSV-2. Influenza A(H3N2), HHV6B, and EBV were the most frequently codetected viruses. Conclusions: Our findings suggest that, in addition to mumps, clinicians should consider respiratory viral (influenza) and herpes viral etiologies for parotitis, particularly among patients without epidemiologic links to mumps cases or outbreaks.

Two Imported Cases of Congenital Rubella Syndrome and Infection-Control Challenges in New York State, 2013-2015.

Rubella was declared eliminated in the United States in 2004. During 2013-2015, 2 infants with congenital rubella syndrome (CRS) were born in New York State. Both mothers were foreign born and traveled to Yemen during their pregnancy. Delayed consideration of CRS led to preventable exposures and a substantial public health response.

Effectiveness of Measles Vaccination and Immune Globulin Post-Exposure Prophylaxis in an Outbreak Setting-New York City, 2013.

BACKGROUND: Measles, mumps, and rubella vaccine (MMR) or immune globulin (IG) are routinely used for measles post-exposure prophylaxis (PEP). However, current literature on the effectiveness of measles PEP is limited and variable. Here, we examined the effectiveness of MMR and IG PEP among children exposed to measles during an outbreak in New York City (NYC) in 2013. METHODS: Contacts were identified by the NYC Department of Health and Mental Hygiene between 13 March 2013 and 30 June 2013. Immunity to measles and receipt of PEP was determined for contacts. PEP effectiveness [(1 - relative risk of developing measles) × 100] was calculated for MMR, IG, and any PEP (MMR or IG) for nonimmune contacts aged <19 years. RESULTS: A total of 3409 contacts were identified, of which 208 (6.1%), 274 (8.0%), and 318 (9.3%) met the inclusion criteria for analysis of MMR, IG, and any PEP effectiveness, respectively. Of the contacts included, 44 received MMR PEP and 77 received IG PEP. Effectiveness of MMR PEP was 83.4% (95% confidence interval [CI], 34.4%, 95.8%). No contact who received IG PEP developed measles; effectiveness of IG PEP was 100% (approximated 95% CI, 56.2%, 99.8%). Effectiveness of receiving any PEP (MMR or IG) was 92.9% (95% CI, 56.2%, 99.8%). CONCLUSIONS: Contacts who received PEP were less likely to develop disease. Our findings support current recommendations for administration of PEP following exposure to measles. These results highlight the importance of a rapid public health outbreak response to limit measles transmission following case identification.

Generalisability of vaccine effectiveness estimates: an analysis of cases included in a postlicensure evaluation of 13-valent pneumococcal conjugate vaccine in the USA.

OBJECTIVES: External validity, or generalisability, is the measure of how well results from a study pertain to individuals in the target population. We assessed generalisability, with respect to socioeconomic status, of estimates from a matched case-control study of 13-valent pneumococcal conjugate vaccine effectiveness for the prevention of invasive pneumococcal disease in children in the USA. DESIGN: Matched case-control study. SETTING: Thirteen active surveillance sites for invasive pneumococcal disease in the USA. PARTICIPANTS: Cases were identified from active surveillance and controls were age and zip code matched. OUTCOME MEASURES: Socioeconomic status was assessed at the individual level via parent interview (for enrolled individuals only) and birth certificate data (for both enrolled and unenrolled individuals) and at the neighbourhood level by geocoding to the census tract (for both enrolled and unenrolled individuals). Prediction models were used to determine if socioeconomic status was associated with enrolment. RESULTS: We enrolled 54.6% of 1211 eligible cases and found a trend toward enrolled cases being more affluent than unenrolled cases. Enrolled cases were slightly more likely to have private insurance at birth (p=0.08) and have mothers with at least some college education (p<0.01). Enrolled cases also tended to come from more affluent census tracts. Despite these differences, our best predictive model for enrolment yielded a concordance statistic of only 0.703, indicating mediocre predictive value. Variables retained in the final model were assessed for effect measure modification, and none were found to be significant modifiers of vaccine effectiveness. CONCLUSIONS: We conclude that although enrolled cases are somewhat more affluent than unenrolled cases, our estimates are externally valid with respect to socioeconomic status. Our analysis provides evidence that this study design can yield valid estimates and the assessing generalisability of observational data is feasible, even when unenrolled individuals cannot be contacted.

Rubella Surveillance and Diagnostic Testing among a Low-Prevalence Population, New York City, 2012-2013.

The New York City Department of Health and Mental Hygiene (DOHMH) receives clinical and laboratory reports for rubella. Because rubella immunoglobulin M (IgM) assays may produce false-positive results and rubella infections may be asymptomatic, interpretation of positive IgM results can be challenging. Rubella reports received by DOHMH in 2012 to 2013 were reviewed. The rubella IgM testing purpose was determined through case investigation. Results of IgM testing by indirect enzyme-linked immunosorbent assay (ELISA) and capture enzyme immunoassay (EIA) were compared to determine positive predictive value (PPV) and specificity. DOHMH received 199 rubella reports; 2 were true cases. Of all reports, 77.9% were tested for rubella IgM erroneously, 19.6% were tested for diagnostic purposes, 2.0% had unknown test purpose, and 0.5% were not tested. PPV of indirect ELISA was 6% overall, 14% for diagnostic tests, and 0% for tests ordered erroneously. PPV of capture EIA was 29% overall, 50% for diagnostic tests, and 0% for tests ordered erroneously. Overall, specificity was 52% for indirect ELISA and 85% for capture EIA. Limiting rubella IgM testing to patients for whom rubella diagnosis is suspected and using a more specific IgM assay have the potential to reduce false-positive rubella IgM results.

Mumps Outbreak Among a Highly Vaccinated University Community-New York City, January-April 2014.

Background: On 14 January 2014, a vaccinated student presented with parotitis. Mumps immunoglobulin M (IgM) testing was negative and reverse-transcription polymerase chain reaction (RT-PCR) testing was not performed, resulting in a missed diagnosis and the start of an outbreak at a New York City (NYC) university. Methods: Mumps case investigations included patient interviews, medical records review, and laboratory testing including mumps serology and RT-PCR. Case patients were considered linked to the outbreak if they attended or had epidemiologic linkage to the university. Epidemiologic, clinical, and laboratory data for outbreak cases residing in NYC were analyzed. Results: Fifty-six NYC residents with mumps were identified with onset between 12 January and 30 April 2014. Fifty-three cases (95%) were university students, 1 (2%) was a staff member, and 2 (4%) had epidemiologic links to the university. The median age was 20 years (range 18-37 years). All cases had parotitis. Three cases were hospitalized, including 1 of 2 cases with orchitis. Fifty-four (96%) cases had received ≥1 mumps-containing vaccine, 1 (2%) was unvaccinated due to religious exemption, and 1 (2%) had unknown vaccination status. Two of the 44 (5%) cases tested by serology were mumps IgM positive, and 27 of the 40 (68%) tested by RT-PCR were positive. Conclusions: Mumps outbreaks can occur in highly vaccinated populations. Mumps should be considered in patients with parotitis regardless of vaccination status. RT-PCR is the preferred testing method; providers should not rely on IgM testing alone. High vaccination coverage and control measures likely limited the extent of the outbreak.