Combining genomics and epidemiology to track mumps virus transmission in the United States.

Unusually large outbreaks of mumps across the United States in 2016 and 2017 raised questions about the extent of mumps circulation and the relationship between these and prior outbreaks. We paired epidemiological data from public health investigations with analysis of mumps virus whole genome sequences from 201 infected individuals, focusing on Massachusetts university communities. Our analysis suggests continuous, undetected circulation of mumps locally and nationally, including multiple independent introductions into Massachusetts and into individual communities. Despite the presence of these multiple mumps virus lineages, the genomic data show that one lineage has dominated in the US since at least 2006. Widespread transmission was surprising given high vaccination rates, but we found no genetic evidence that variants arising during this outbreak contributed to vaccine escape. Viral genomic data allowed us to reconstruct mumps transmission links not evident from epidemiological data or standard single-gene surveillance efforts and also revealed connections between apparently unrelated mumps outbreaks.

Hospitalized patients with 2009 H1N1 influenza in the United States, April-June 2009.

BACKGROUND: During the spring of 2009, a pandemic influenza A (H1N1) virus emerged and spread globally. We describe the clinical characteristics of patients who were hospitalized with 2009 H1N1 influenza in the United States from April 2009 to mid-June 2009. METHODS: Using medical charts, we collected data on 272 patients who were hospitalized for at least 24 hours for influenza-like illness and who tested positive for the 2009 H1N1 virus with the use of a real-time reverse-transcriptase-polymerase-chain-reaction assay. RESULTS: Of the 272 patients we studied, 25% were admitted to an intensive care unit and 7% died. Forty-five percent of the patients were children under the age of 18 years, and 5% were 65 years of age or older. Seventy-three percent of the patients had at least one underlying medical condition; these conditions included asthma; diabetes; heart, lung, and neurologic diseases; and pregnancy. Of the 249 patients who underwent chest radiography on admission, 100 (40%) had findings consistent with pneumonia. Of the 268 patients for whom data were available regarding the use of antiviral drugs, such therapy was initiated in 200 patients (75%) at a median of 3 days after the onset of illness. Data suggest that the use of antiviral drugs was beneficial in hospitalized patients, especially when such therapy was initiated early. CONCLUSIONS: During the evaluation period, 2009 H1N1 influenza caused severe illness requiring hospitalization, including pneumonia and death. Nearly three quarters of the patients had one or more underlying medical conditions. Few severe illnesses were reported among persons 65 years of age or older. Patients seemed to benefit from antiviral therapy.

Use of a reduced (4-dose) vaccine schedule for postexposure prophylaxis to prevent human rabies: recommendations of the advisory committee on immunization practices.

This report summarizes new recommendation and updates previous recommendations of the Advisory Committee on Immunization Practices (ACIP) for postexposure prophylaxis (PEP) to prevent human rabies (CDC. Human rabies prevention---United States, 2008: recommendations of the Advisory Committee on Immunization Practices. MMWR 2008;57[No. RR-3]). Previously, ACIP recommended a 5-dose rabies vaccination regimen with human diploid cell vaccine (HDCV) or purified chick embryo cell vaccine (PCECV). These new recommendations reduce the number of vaccine doses to four. The reduction in doses recommended for PEP was based in part on evidence from rabies virus pathogenesis data, experimental animal work, clinical studies, and epidemiologic surveillance. These studies indicated that 4 vaccine doses in combination with rabies immune globulin (RIG) elicited adequate immune responses and that a fifth dose of vaccine did not contribute to more favorable outcomes. For persons previously unvaccinated with rabies vaccine, the reduced regimen of 4 1-mL doses of HDCV or PCECV should be administered intramuscularly. The first dose of the 4-dose course should be administered as soon as possible after exposure (day 0). Additional doses then should be administered on days 3, 7, and 14 after the first vaccination. ACIP recommendations for the use of RIG remain unchanged. For persons who previously received a complete vaccination series (pre- or postexposure prophylaxis) with a cell-culture vaccine or who previously had a documented adequate rabies virus-neutralizing antibody titer following vaccination with noncell-culture vaccine, the recommendation for a 2-dose PEP vaccination series has not changed. Similarly, the number of doses recommended for persons with altered immunocompetence has not changed; for such persons, PEP should continue to comprise a 5-dose vaccination regimen with 1 dose of RIG. Recommendations for pre-exposure prophylaxis also remain unchanged, with 3 doses of vaccine administered on days 0, 7, and 21 or 28. Prompt rabies PEP combining wound care, infiltration of RIG into and around the wound, and multiple doses of rabies cell-culture vaccine continue to be highly effective in preventing human rabies.

Cost effectiveness of pertussis vaccination in adults.

BACKGROUND: Prior economic analyses have reached disparate conclusions about whether vaccinating adults against pertussis would be cost effective. Newly available data on pertussis incidence were used to evaluate the cost effectiveness of one-time adult vaccination and adult vaccination with decennial boosters. METHODS: A Markov model was used to calculate the health benefits, risks, costs, and cost effectiveness of the following strategies: (1) no adult pertussis vaccination, (2) one-time adult vaccination at 20-64 years, and (3) adult vaccination with decennial boosters. The impact of the severity of pertussis illness, vaccine adverse events, and herd immunity on model outcomes were also examined. RESULTS: At a disease incidence of 360 per 100,000, the one-time adult vaccination strategy would prevent 2.8 million cases, and the decennial vaccination strategy would prevent 8.3 million cases. As disease incidence varied from 10 to 500 per 100,000, the one-time adult vaccination strategy was projected to prevent 79,000 to 3.8 million adult pertussis cases, while the decennial vaccination program would prevent 239,000 to 11.4 million cases. A one-time adult vaccination strategy would result in 106 million people vaccinated, or approximately 64% of the adult cohort, for a total program cost of $2.1 billion, while a decennial vaccination strategy would cost $6.7 billion. The one-time and decennial booster vaccination strategies result in cost-effectiveness ratios of <$50,000 per quality-adjusted life year saved if disease incidence in adults were greater than 120 cases per 100,000 population. CONCLUSIONS: Routine vaccination of adults aged 20 to 64 years with combined tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis is cost effective if pertussis incidence in this age group is greater than 120 per 100,000 population.

Gaps in vaccine financing for underinsured children in the United States.

CONTEXT: The number of new vaccines recommended for children and adolescents has nearly doubled during the past 5 years, and the cost of fully vaccinating a child has increased dramatically in the past decade. Anecdotal reports from state policy makers and clinicians suggest that new gaps have arisen in financial coverage of vaccines for children who are underinsured (ie, have private insurance that does not cover all recommended vaccines). In 2000, approximately 14% of children were underinsured for vaccines in the United States. OBJECTIVES: To describe variation among states in the provision of new vaccines to underinsured children and to identify barriers to state purchase and distribution of new vaccines. DESIGN, SETTING, AND PARTICIPANTS: A 2-phase mixed-methods study of state immunization program managers in the United States. The first phase included 1-hour qualitative telephone interviews conducted from November to December 2005 with 9 program managers chosen to represent different state vaccine financing policies. The second phase incorporated findings from phase 1 to develop a national telephone and paper-based survey of state immunization program managers that was conducted from January to June 2006. MAIN OUTCOME MEASURES: Percentage of states in which underinsured children are unable to receive publicly purchased vaccines in the private or public sectors. RESULTS: Immunization program managers from 48 states (96%) participated in the study. Underinsured children were not eligible to receive publicly purchased meningococcal conjugate or pneumococcal conjugate vaccines in the private sector in 70% and 50% of states, respectively, or in the public sector in 40% and 17% of states, respectively. Due to limited financing for new vaccines, 10 states changed their policies for provision of publicly purchased vaccines between 2004 and early 2006 to restrict access to selected new vaccines for underinsured children. The most commonly cited barriers to implementation in underinsured children were lack of sufficient federal and state funding to purchase vaccines. CONCLUSIONS: The current vaccine financing system has resulted in gaps for underinsured children in the United States, many of whom are now unable to receive publicly purchased vaccines in either the private or public sectors. Additional strategies are needed to ensure financial coverage for all vaccines, particularly new vaccines, among this vulnerable population.

Increasing evidence of immunity to varicella among children in Massachusetts, 1999-2003.

BACKGROUND: Experiences with vaccine-preventable diseases have demonstrated the success of school-entry requirements in increasing vaccination coverage and decreasing disease incidence. This study examines the effect of early implementation of daycare and school-entry requirements for varicella vaccination on recorded varicella immunity of preschool and school-aged children in Massachusetts. METHODS: Immunization surveys were conducted in licensed child care centers and schools with kindergarten and/or 7th grades. Evidence of immunity to varicella was defined as having physician verified records of varicella vaccination or disease history from the 1999-2000 through 2003-2004 school years. RESULTS: During the 5-year study period, physician-certified reliable history of varicella disease decreased in each grade level while vaccination coverage increased. The increase in the number of children in each grade level receiving varicella vaccine led to an increase in the overall percentage of children with evidence of immunity to varicella: 85% to 97% for children aged 2 years or more in child care, 93% to 98% for children in kindergarten, and 88% to 92% for children in 7th grade. CONCLUSIONS: The implementation of daycare and school-entry requirements for varicella vaccination within 4 years of the start of the varicella vaccination program in Massachusetts was associated with high levels of vaccination coverage in the cohorts of children targeted by the requirements. Although evidence of immunity from varicella disease decreased during the study period, the increase in varicella vaccination coverage compensated for the decline in disease history, resulting in a higher proportion of young children with evidence of immunity to varicella.

The incidence of varicella and herpes zoster in Massachusetts as measured by the Behavioral Risk Factor Surveillance System (BRFSS) during a period of increasing varicella vaccine coverage, 1998-2003.

BACKGROUND: The authors sought to monitor the impact of widespread varicella vaccination on the epidemiology of varicella and herpes zoster. While varicella incidence would be expected to decrease, mathematical models predict an initial increase in herpes zoster incidence if re-exposure to varicella protects against reactivation of the varicella zoster virus. METHODS: In 1998-2003, as varicella vaccine uptake increased, incidence of varicella and herpes zoster in Massachusetts was monitored using the random-digit-dial Behavioral Risk Factor Surveillance System. RESULTS: Between 1998 and 2003, varicella incidence declined from 16.5/1,000 to 3.5/1,000 (79%) overall with > or = 66% decreases for all age groups except adults (27% decrease). Age-standardized estimates of overall herpes zoster occurrence increased from 2.77/1,000 to 5.25/1,000 (90%) in the period 1999-2003, and the trend in both crude and adjusted rates was highly significant (p < 0.001). Annual age-specific rates were somewhat unstable, but all increased, and the trend was significant for the 25-44 year and 65+ year age groups. CONCLUSION: As varicella vaccine coverage in children increased, the incidence of varicella decreased and the occurrence of herpes zoster increased. If the observed increase in herpes zoster incidence is real, widespread vaccination of children is only one of several possible explanations. Further studies are needed to understand secular trends in herpes zoster before and after use of varicella vaccine in the United States and other countries.

Societal costs and morbidity of pertussis in adolescents and adults.

BACKGROUND: Since the 1980s, the reported incidence of pertussis among adolescents and adults has been steadily increasing. To understand whether the benefits of an acellular pertussis vaccine formulated for adolescents and adults might offset its costs, policy makers will need information about morbidity and societal (medical and nonmedical) costs of pertussis. METHODS: Adolescents (age, 10-17 years) and adults (age, >or=18 years) with confirmed pertussis illness were identified by the Massachusetts enhanced pertussis surveillance system. We evaluated medical costs in a cohort of patients who had confirmed pertussis during the period of January 1998 through December 2000; nonmedical costs, by means of prospective interviews, in a cohort of patients who had confirmed pertussis during the period of December 2001 through January 2003; and morbidity in both cohorts. Our main outcome measures were mean costs per case, in 2002 US dollars. RESULTS: In the analysis of medical costs, 1679 adolescents and 936 adults were found to have mean costs of 242 dollars and 326 dollars, respectively (P<.05). In interviews with 314 adolescents and 203 adults, adults had significantly higher nonmedical costs (447 dollars) than those of adolescents (155 dollars). A total of 83% of adolescents missed a mean of 5.5 days from school (range, 0.4-32 days), and 61% of adults missed a mean of 9.8 days from work (range, 0.1-180 days) because of pertussis. Thirty-eight percent of adolescents and 61% of adults were still coughing at the time of the interview, which occurred an average of 106 days and 94 days, respectively, after cough onset. CONCLUSIONS: Pertussis causes significant morbidity in and costs for adolescents and adults, with time losses comprising the largest proportion of the cost. Societal costs should be considered when making decisions about potential vaccine use in the future.

Infant pertussis: who was the source?

BACKGROUND: In the United States in the 1990s, the incidence of reported pertussis in adults, adolescents and infants increased; infants younger than 1 year of age had the highest reported incidence. METHODS: In 4 states with Enhanced Pertussis Surveillance, we examined the epidemiology of reported pertussis cases to determine the source of pertussis among infants. A source was defined as a person with an acute cough illness who had contact with the case-infant 7-20 days before the infant's onset of cough. RESULTS: The average annual pertussis incidence per 100,000 infants younger than 1 year of age varied by state: 22.9 in Georgia; 42.1 in Illinois; 93.0 in Minnesota; and 35.8 in Massachusetts. Family members of 616 (80%) of 774 reported case-infants were interviewed; a source was identified for 264 (43%) of the 616 case-infants. Among the 264 case-infants, mothers were the source for 84 (32%) and another family member was the source for 113 (43%). Of the 219 source-persons with known age, 38 (17%) were age 0-4 years, 16 (7%) were age 5-9 years, 43 (20%) were age 10-19 years, 45 (21%) were age 20-29 years and 77 (35%) were age > or =30 years. CONCLUSIONS: The variation in reported pertussis incidence in the 4 states might have resulted from differences in awareness of pertussis among health care providers, diagnostic capacity and case classification. Among case-infants with an identifiable source, family members (at any age) were the main source of pertussis. Understanding the source of pertussis transmission to infants may provide new approaches to prevent pertussis in the most vulnerable infants.

Surveillance for transmission and antibiotic adverse events among neonates and adults exposed to a healthcare worker with pertussis.

BACKGROUND: During a hospital obstetric rotation, a medical student demonstrated classic symptoms of pertussis. The diagnosis was confirmed by isolation of Bordetella pertussis. Because this exposure occurred in a high-risk hospital setting, control measures were undertaken to prevent transmission and illness. OBJECTIVES: To identify secondary cases of pertussis, to determine compliance with chemoprophylaxis recommendations, and to monitor for adverse events associated with chemoprophylaxis following a hospital exposure to pertussis. PATIENTS: More than 500 individuals were potentially exposed, including 168 neonates; antimicrobial chemoprophylaxis was administered to 281 individuals. Fifty-eight neonates and 194 adults began azithromycin chemoprophylaxis; 18 neonates and 2 adults began erythromycin chemoprophylaxis. METHODS: Active surveillance was instituted for (1) secondary cases of pertussis among healthcare coworkers, obstetric patients, their neonates, and labor companions and (2) antibiotic compliance and tolerance. RESULTS: No secondary cases of pertussis were confirmed by laboratory tests; however, 26 suspected cases and 5 clinically compatible cases were identified. Antibiotic courses were completed by 95% of the individuals who initiated therapy. Neonates taking azithromycin had statistically significantly less gastrointestinal distress compared with neonates taking erythromycin (12% vs 50%; P = .002); there were no cases of infantile hypertrophic pyloric stenosis. CONCLUSIONS: Although it was not possible to assess the effectiveness of the antibiotic regimens, the lack of laboratory-confirmed secondary cases suggests control measures were successful. Data from the 58 neonates who received azithromycin suggest it may be well tolerated in this age group.

Pediatricians' self-reported clinical practices and adherence to national immunization guidelines after the introduction of pneumococcal conjugate vaccine.

BACKGROUND: Little is known about whether pneumococcal conjugate vaccine (PCV) has altered pediatricians' practices regarding well-child and acute care. OBJECTIVES: To (1) describe whether PCV caused pediatricians to move other routine infant vaccines and/or add routine visits; (2) characterize adherence to national immunization recommendations; and (3) determine whether PCV altered pediatricians' planned clinical approach to well-appearing febrile infants. DESIGN AND METHODS: One year after PCV was added to the pediatric immunization schedule, we mailed a 23-item survey to 691 randomly selected pediatricians in Massachusetts. The adjusted response rate was 77%. RESULTS: After PCV introduction, 39% of pediatricians moved other routine infant vaccines to different visits and 15% added routine visits to the infant schedule. The self-reported immunization schedules of 36% were nonadherent to national immunization guidelines for at least 1 vaccine. Nonadherence rates were significantly higher among pediatricians who had been in practice longer, moved another vaccine because of PCV introduction, and/or offered to give shots later when multiple injections were due. For a hypothetical febrile 8-month-old girl who had received 3 doses of PCV, pediatricians reported they were significantly less likely to (1) perform both blood and urine testing and (2) prescribe antibiotics than in the pre-PCV era. CONCLUSIONS: The introduction of PCV may have had unintended effects on pediatric primary care, including decreased adherence to national recommendations for the timing of immunizations and decreased urine testing for well-appearing febrile infants. Special efforts may be warranted to ensure that pediatricians remain current with changing recommendations.

Pediatricians' views on financial barriers and values for pneumococcal vaccine for children.

OBJECTIVES: To 1) describe barriers to pneumococcal conjugate vaccine adoption and 2) estimate the value of the vaccine based on pediatricians' responses to willingness-to-pay questions. METHODS: In June 2000, we mailed a random sample of pediatricians in Massachusetts a questionnaire about barriers to adoption of the vaccine and willingness to pay for the vaccine and associated outcomes. Respondents were assigned at random to 1 of 2 survey versions: the Personal Perspective version, for which they imagined spending their own money for their own child, or the Public Perspective version, for which they imagined spending the government's money for the average child. RESULTS: Of the 546 pediatricians who responded (estimated completion rate, 80%), only 9% were using the vaccine routinely at the time of the survey. Most said that if the state did not provide the vaccine, financial barriers including inadequate insurance reimbursement would limit their use of the vaccine either a great deal (61%) or a moderate amount (25%). Pediatricians who were asked how much they would pay for the vaccine for their own child (personal perspective) gave a mean of $56 per dose, whereas those who were asked how much the government should pay on behalf of an average child (public perspective) gave a mean of $36 per dose. Alternatively, when we used a decision analysis model and incorporated pediatricians' values for preventing pneumococcal infections to estimate the vaccine's value, the value per dose was $38 from the personal perspective and $34 from the public perspective. CONCLUSIONS: Pediatricians in Massachusetts identified significant financial barriers to the adoption of pneumococcal conjugate vaccine related to insurance arrangements. Based on willingness-to-pay questions, the value of the vaccine is lower than the current list price. The methods used to estimate the value of a vaccine, including the perspective used to frame questions, may substantially influence the results.

Enzyme-linked immunospot assay detection of mumps-specific antibody-secreting B cells as an alternative method of laboratory diagnosis.

Although high measles, mumps, and rubella (MMR) vaccination coverage has been successful in dramatically reducing mumps disease in the United States, mumps (re)infections occasionally occur in individuals who have been either previously vaccinated or naturally infected. Standard diagnostics that detect virus or virus-specific antibody are dependable for confirming primary mumps infection in immunologically naïve persons, but these methods perform inconsistently for individuals with prior immune exposure. We hypothesized that detection of activated mumps-specific antibody-secreting B cells (ASCs) by enzyme-linked immunospot (ELISPOT) assay could be used as a more reliable diagnostic. To test this, a time course of virus-specific ASC responses was measured by ELISPOT assay following MMR vaccination of 16 previously vaccinated or naturally exposed adult volunteers. Mumps-specific ASCs were detectable in 68% of these individuals at some point during the first 3 weeks following revaccination. In addition, mumps-specific ASCs were detected in 7/7 previously vaccinated individuals who recently had been infected as part of a confirmed mumps outbreak. These data suggest that ELISPOT detection of mumps-specific ASCs has the potential for use as an alternative method of diagnosis when suspect cases cannot be confirmed by detection of IgM or virus. In addition, it was determined that mumps-specific memory B cells are detected at a much lower frequency than measles- or rubella-specific cells, suggesting that mumps infection may not generate robust B-cell memory.

Evidence for a 4-dose vaccine schedule for human rabies post-exposure prophylaxis in previously non-vaccinated individuals.

After exposure, human rabies is preventable by prompt application of post-exposure prophylaxis. Historically, the total number of rabies vaccine doses administered during human prophylaxis has decreased, as modern biologics have improved and scientific knowledge has grown. A review of the literature on rabies virus pathogenesis, experimental animal studies, clinical trials, epidemiological surveillance, and economic analyses was conducted to determine the potential utility of reducing the current 5-dose intramuscular series of human rabies vaccine administered in the United States. Based upon the available evidence, a reduced schedule of cell-culture rabies vaccine, administered on days 0, 3, 7, and 14, given in conjunction with rabies immune globulin, was supported and recommended by the United States Advisory Committee on Immunization Practices.

Pertussis in adolescents and adults: should we vaccinate?

BACKGROUND: The incidence of reported pertussis among adolescents, adults, and young infants has increased sharply over the past decade. Combined acellular pertussis vaccines for adolescents and adults are available in Canada, Australia, and Germany and may soon be considered for use in the United States. OBJECTIVE: To evaluate the potential health benefits, risks, and costs of a national pertussis vaccination program for adolescents and/or adults. DESIGN, SETTING, AND POPULATION: The projected health states and immunity levels associated with pertussis disease and vaccination were simulated with a Markov model. The following strategies were examined from the health care payer and societal perspectives: (1) no vaccination; (2) 1-time adolescent vaccination; (3) 1-time adult vaccination; (4) adult vaccination with boosters; (5) adolescent and adult vaccination with boosters; and (6) postpartum vaccination. Data on disease incidence, costs, outcomes, vaccine efficacy, and adverse events were based on published studies, recent unpublished clinical trials, and expert panel input. MAIN OUTCOME MEASURES: Cases prevented, adverse events, costs (in 2004 US dollars), cost per case prevented, and cost per quality-adjusted life-year (QALY) saved. RESULTS: One-time adolescent vaccination would prevent 30800 cases of pertussis (36% of projected cases) and would result in 91000 vaccine adverse events (67% local reactions). If pertussis vaccination cost $15 and vaccine coverage was 76%, then 1-time adolescent vaccination would cost $1100 per case prevented (or $1200 per case prevented) or $20000 per QALY (or $23000 per QALY) saved, from the societal (or health care payer) perspective. With a threshold of $50000 per QALY saved, the adolescent and adult vaccination with boosters strategy became potentially cost-effective from the societal perspective only if 2 conditions were met simultaneously, ie, (1) the disease incidence for adolescents and adults was > or =6 times higher than base-case assumptions and (2) the cost of vaccination was less than $10. Adult vaccination strategies were more costly and less effective than adolescent vaccination strategies. The results were sensitive to assumptions about disease incidence, vaccine efficacy, frequency of vaccine adverse events, and vaccine costs. CONCLUSIONS: Routine pertussis vaccination of adolescents results in net health benefits and may be relatively cost-effective.

Exemptions to school immunization requirements: the role of school-level requirements, policies, and procedures.

OBJECTIVES: Our goal was to determine whether school-level variability in implementation of immunization requirements is associated with the likelihood of a child having received an exemption to school immunization requirements. METHODS: We surveyed 1000 school immunization personnel in Colorado, Massachusetts, Missouri, and Washington. We explored associations between school implementation of immunization requirements and the likelihood of a child having an exemption using logistic regression models. RESULTS: School policies associated with an increased likelihood of children having exemptions included lack of provision of written instructions for completing the school immunization requirement before enrollment, administrative procedures making it easier to claim an exemption, and granting of philosophical exemptions. In the 2 states we surveyed where philosophical exemptions are not authorized (Massachusetts and Missouri), 17.0% and 18.1% of schools reported permitting philosophical exemptions. CONCLUSIONS: Inconsistencies in the interpretation and implementation of school immunization laws contribute to variability in rates of exemptions. School policies should be reviewed to ensure consistency with the intent of state laws.

Two Outbreaks of Salmonella enteritidis Associated with Monte Cristo Sandwiches.

We report on two outbreaks of Salmonella enteritidis which occurred in 1992; both were associated with Monte Cristo sandwiches. The first outbreak, which occurred in Woods Hole, Massachusetts, was investigated as a case-control study, and involved 74 persons. The second outbreak, investigated as a cohort study, occurred in Brewster, Massachusetts, and involved 32 persons. Monte Cristo sandwiches were strongly implicated in both outbreaks; the odds ratio in the case-control study was 43, and the relative risk in the cohort study was 13. Food-preparation procedures were reviewed and food handlers were educated about safe food-preparation practices. Because of the short grilling time for Monte Cristo sandwiches, (usually several minutes) the eggs used in the preparation may only be partially cooked. As a result, this food should be viewed as high risk for S. enteritidis . Pasteurized eggs should be used to prepare Monte Cristo sandwiches, especially in a commercial setting.