The epidemiologic features of this outbreak suggest that intense exposures, particularly among boys in schools, facilitated transmission and overcame vaccine-induced protection in these patients. High rates of two-dose coverage reduced the severity of the disease and the transmission to persons in settings of less intense exposure.

This is the first report of measles transmission from a twice-vaccinated individual with documented secondary vaccine failure. The clinical presentation and laboratory data of the index patient were typical of measles in a naive individual. Secondary patients had robust anamnestic antibody responses. No tertiary cases occurred despite numerous contacts. This outbreak underscores the need for thorough epidemiologic and laboratory investigation of suspected cases of measles regardless of vaccination status.

NI treatment is likely to be effective at reducing mortality among hospitalized patients, and symptom duration by up to 1 day in the general population. Oseltamivir or zanamivir prophylaxis are likely to be effective at reducing secondary symptomatic influenza transmission. Increased nausea and vomiting are likely associated with oseltamivir use. We recommend that decisions regarding NI use are made in consideration of potential adverse events, particularly for the general population at low risk of complications. Among hospitalized patients, NI administration seems warranted to reduce mortality risk.

Determinants of protective immunity against SARS-CoV-2 infection require the development of well-standardized, reproducible antibody assays. This need has led to the emergence of a variety of neutralization assays. Head-to-head evaluation of different SARS-CoV-2 neutralization platforms could facilitate comparisons across studies and laboratories. Five neutralization assays were compared using forty plasma samples from convalescent individuals with mild-to-moderate COVID-19: four cell-based systems using either live recombinant SARS-CoV-2 or pseudotyped viral particles created with lentivirus (LV) or vesicular stomatitis virus (VSV) packaging and one surrogate ELISA-based test that measures inhibition of the spike protein receptor binding domain (RBD) binding its receptor, human angiotensin converting enzyme 2 (hACE2). Vero, Vero E6, HEK293T expressing hACE2, and TZM-bl cells expressing hACE2 and transmembrane serine protease 2 were tested. All cell-based assays showed 50% neutralizing dilution (ND50) geometric mean titers (GMTs) that were highly correlated (Pearson r = 0.81–0.89) and ranged within 3.4-fold. The live-virus assay and LV-pseudovirus assays with HEK293T/hACE2 cells showed very similar mean titers: 141 and 178, respectively. ND50 titers positively correlated with plasma IgG targeting SARS-CoV-2 spike and RBD ( r = 0.63–0.89), but moderately correlated with nucleoprotein IgG ( r = 0.46–0.73). ND80 GMTs mirrored ND50 data and showed similar correlation between assays and with IgG concentrations. The VSV-pseudovirus assay and LV-pseudovirus assay with HEK293T/hACE2 cells in low and high-throughput versions were calibrated against the WHO SARS-CoV-2 IgG standard. High concordance between the outcomes of cell-based assays with live and pseudotyped virions enables valid cross-study comparison using these platforms. 249

A mumps outbreak in upstate New York in 2009 at a summer camp for Orthodox Jewish boys spread into Orthodox Jewish communities in the Northeast, including New York City. The availability of epidemiologic information, including vaccination records and parotitis onset dates, allowed an enhanced analysis of laboratory methods for mumps testing. Serum and buccal swab samples were collected from 296 confirmed cases with onsets from September through December 2009. All samples were tested using the Centers for Disease Control and Prevention (CDC) capture IgM enzyme immunoassay (EIA) and a real-time reverse transcription-PCR (rRT-PCR) that targets the short hydrophobic gene. A subset of the samples (n ‫؍‬ 205) was used to evaluate 3 commercial mumps IgM assays and to assess the sensitivity of using an alternative target gene (nucleoprotein) in the rRT-PCR protocol. Among 115 cases of mumps with 2 documented doses of measles, mumps, and rubella (MMR) vaccine, the CDC capture IgM EIA detected IgM in 51% of serum samples compared to 9% to 24% using three commercial IgM assays. The rRT-PCR that targeted the nucleoprotein gene increased RNA detection by 14% compared to that obtained with the original protocol. The ability to detect IgM improved when serum was collected 3 days or more after symptom onset, whereas sensitivity of RNA detection by rRT-PCR declined when buccal swabs were collected later than 2 days after onset. Selection of testing methods and timing of sample collection are important factors in the ability to confirm infection among vaccinated persons. These results reinforce the need to use virus detection assays in addition to serologic tests.