Mumps transmission in hospitals.

Although sporadic transmission of mumps within hospitals to patients and staff is well documented, outbreaks of mumps within hospitals have only rarely been reported. The widespread mumps outbreaks that occurred in Tennessee in 1986-1987 provided an opportunity to assess the extent of the problems caused by mumps in hospitals. Information was obtained from 146 (95%) of 154 infection control practitioners in the state. Infection control problems caused by mumps were reported from 17 (12%) of 146 hospitals. The 17 hospitals in which these incidents occurred were located in counties that accounted for 67% of the reported mumps cases statewide during this period. Although most cases of mumps in health care workers were community-acquired, six health care workers in three different hospitals developed mumps following nosocomial exposure. In two institutions, nine patients contracted mumps while hospitalized. Both were long-term-care facilities housing adolescents, who had substantial contact with a community where mumps outbreaks were ongoing. This study suggests that mumps poses a small but real risk to both patients and staff in hospitals, particularly in long-term-care facilities caring for adolescents and young adults. In communities where mumps activity is ongoing, hospitals should consider identifying potentially susceptible staff members at risk for infection and offering vaccine. Likewise, susceptible patients in long-term-care facilities should be immunized.

Overview of policies affecting vaccine use in child day care.

Vaccination policies for preschool-age children, including those in child day care, have undergone frequent changes within the past several years in response to the development of new vaccines (DTaP, Hib conjugate vaccines), the changing epidemiology of vaccine-preventable diseases (measles), and the establishment of new objectives for the control and elimination of vaccine-preventable diseases (Hib, hepatitis B). The acquisition and spread of vaccine-preventable diseases can be minimized in child day-care settings by vaccinating all children, establishing a continuing system by which all children remain fully vaccinated on schedule, providing educational materials to parents about the recommended schedule of routine childhood vaccines, and implementing new recommendations for vaccine use.

Childhood upper respiratory tract infections: to what degree is incidence affected by day-care attendance?

Risk factors for acute upper respiratory tract disease in childhood were evaluated in a population-based sample of the Atlanta metropolitan area. Mothers from 449 households containing 575 children less than 5 years of age were selected by random-digit dialing and questioned about upper respiratory tract infection and ear infection occurring in their children during the preceding 2 weeks. Household demographic and socioeconomic characteristics, maternal smoking history and child day-care attendance and breast-feeding information were also obtained. For children less than 5 years of age, the reported incidence of upper respiratory tract infection was 24%, and of ear infection, 6%. Controlling for the other variables measured, day-care attendance was associated with a significantly increased risk of both illnesses. For upper respiratory tract infection, increased risk was present for all children attending day care (P = .02, odds ratio = 1.6), whereas for ear infection, risk could be demonstrated only for full-time attendees (P = .005, odds ratio = 3.8). Maternal smoking was a second independent risk factor for a child's having upper respiratory tract infection (odds ratio = 1.7, P = .01). Thirty-one percent of all upper respiratory tract infection among day-care attendees and 66% of all ear infections among full-time day-care attendees were attributable to day-care attendance. Given the proportion of children in day care, 9% to 14% of the total burden of upper respiratory tract disease in this population was day care related.(ABSTRACT TRUNCATED AT 250 WORDS)

Changing epidemiology of mumps and its impact on university campuses.

The reported incidence of mumps has declined dramatically since licensure of the live attenuated mumps vaccine in the United States in 1967, particularly in young children. Because administration of the vaccine was not widely practiced during the first decade it was available, there is now a cohort of teenagers and young adults who are relatively underimmunized. Reported mumps cases in this cohort increased substantially during 1986 to 1987. Mumps outbreaks at three Illinois universities, from which 123 clinical cases were reported between September 1986 and May 1987, were investigated. Meningeal involvement was reported in 17% of case-patients, orchitis occurred in 19% of 64 men, 6% of patients were hospitalized, and direct health care costs were estimated at $264 per case and more than $32,000 for the three outbreaks combined. The risk of mumps illness was greater for students less than 20 years of age (relative risk [RR] = 2.1, 95% confidence interval [CI] = 1.4, 3.1); students residing in dormitories (RR = 2.7, 95% CI = 1.6, 4.6); and out-of-state students (RR = 1.8, 95% CI = 1.0, 3.0). Because the available data suggest that mumps in college-aged persons is due chiefly to a failure to vaccinate susceptible persons, colleges and universities should become one major focus of mumps prevention activities to reduce susceptibility in this high-risk population.

Control of epidemic group A meningococcal meningitis in Nepal.

During the first six months of 1983, an epidemic of serogroup A meningococcal meningitis occurred in the Kathmandu valley of Nepal, resulting in 875 cases and 95 deaths. The annual attack rate was 103 cases per 100,000 population, with a peak attack rate occurring in April. Epidemic meningococcal disease had not been recognized previously in Nepal. Early in 1984, a review of hospital-based data on pyogenic meningitis in Kathmandu showed three times as many cases per month compared with the same period the previous year, suggesting that a recurrent epidemic was unfolding. Beginning in February 1984, a vaccination campaign directed at a high-risk target population of people aged 1-24 years was launched; over 329,000 doses of bivalent A/C meningococcal vaccine were given, achieving approximately 64% coverage of the target population. A dramatic decline in the number of new meningitis cases occurred coincident with the initiation of the mass vaccination campaign. This experience demonstrates that it is possible, with appropriate surveillance efforts, to detect an evolving epidemic of meningococcal disease early in its course and to institute control measures in advance of the expected epidemic peak.

Defining surrogate serologic tests with respect to predicting protective vaccine efficacy: poliovirus vaccination.

Inactivated and trivalent oral poliovirus vaccines contain either formalin-inactivated or live, attenuated poliovirus, respectively, of the three serotypes. Interference among the three attenuated poliovirus serotypes was minimized with a "balanced-formulation" vaccine, and serologic responses after IPV were optimized by adjusting the antigenic content of each inactivated poliovirus serotype. Seroconversion is dependent on both the relative content as well as the absolute quantity of virus in the vaccine. The "gold standard" method to assess humoral antibody responses following vaccination is the neutralization assay. Any detectable titer of neutralizing antibody against poliovirus is considered protective against clinical paralytic diseases. Recently, standard procedures were adopted for conducting neutralization assays. Efforts are being undertaken now to develop a combined diphtheria and tetanus toxoids and pertussis vaccine and IPV vaccine in the United States using a dual-chambered syringe that mixes the content of both vaccines at the time of injection; this approach is necessary to overcome the potential detrimental effect of thimerosal on IPV (the preservative in DTP). Other vaccines that combine DTP and/or Haemophilus influenzae type b and/or hepatitis B with IPV appear feasible but require further investigation. New combination vaccines should induce similar or superior levels of neutralizing antibody in serum for individual protection against paralytic disease and mucosal immunity that effectively decreases viral replication in the intestine and pharynx for population protection against transmission of poliovirus.

Completeness of reporting for paralytic poliomyelitis, United States, 1980 through 1991. Implications for estimating the risk of vaccine-associated disease.

BACKGROUND: Although the risk of vaccine-associated paralytic poliomyelitis (VAPP) has remained relatively constant during the past 30 years, estimates of VAPP depend largely on the completeness of reporting to the existing passive surveillance system. The National Vaccine Injury Compensation Program constitutes an alternative system for reporting VAPP, and data available from this system permitted us to evaluate the completeness of the national poliomyelitis surveillance system. METHODS: We compared cases of paralytic poliomyelitis reported to the national surveillance system (maintained by the Centers for Disease Control and Prevention, Atlanta, Ga) with cases recommended for compensation by the National Vaccine Injury Compensation Program, Rockville, Md, and we calculated the observed completeness of reporting to the national system for 1980 through 1991. A capture-recapture method was also used to estimate completeness of reporting, ie, to account for cases potentially missed by both systems. In addition, we reviewed the epidemiology and updated the risk of VAPP based on the most current information on cases of VAPP. RESULTS: From 1980 through 1991, 105 cases of paralytic poliomyelitis were identified by the Centers for Disease Control and Prevention and National Vaccine Injury Compensation Program systems, 98 (93%) of which were VAPP (average, 8.2 cases per year). The observed completeness of reporting to the Centers for Disease Control and Prevention was 94%, and the estimated completeness of reporting (capture-recapture method) was 81%. The overall risk of VAPP was one case per 2.5 million doses of oral poliovirus vaccine distributed. In the sensitivity analysis, the risk estimates of VAPP remained relatively stable throughout a wide range of assumptions regarding underreporting and specificity of the case definition for paralytic poliomyelitis. CONCLUSION: The risk of VAPP remains virtually unchanged from previous estimates despite the inclusion of previously unidentified VAPP cases. Despite the potential for both underreporting and misclassification of cases, our risk estimates were relatively insensitive to either of these biases. Since both of these biases were in opposite directions, and both probably occurred with low frequency, the risk estimates provided in this report appear valid and approximate the "true" risk of VAPP in the United States.

Measles, mumps, and rubella vaccines.

With widespread use of the live virus vaccines for measles, mumps, and rubella, there has been a dramatic decrease in the incidence of all three diseases. At the same time, an increasing proportion of the remaining cases are occurring in adolescents and adults. Thus, vaccinations for these three diseases of childhood must be included in a comprehensive program for adult immunization. The vaccines have a proven history of safety and efficacy and are usually administered together as combined measles-mumps-rubella (MMR) vaccine. Vaccination for measles, mumps, and rubella is particularly important for susceptible adults likely to come in contact with infected children. Adults at particularly high risk for exposure may include daycare center workers, teachers and other school employees, college students, medical personnel, and those planning to travel outside the United States.

Poliomyelitis eradication: progress, challenges for the end game, and preparation for the post-eradication era.

In 1988, the World Health Assembly resolved to eradicate poliomyelitis globally by the year 2000. Dramatic progress toward this goal has occurred: three of the six WHO regions (Region of the Americas, European Region, and Western Pacific Region) are now polio free; and the number of polio-endemic countries decreased from over 125 in 1988 to 30 in 1999. Intensified efforts currently are underway to reach the target as soon as possible after 2000 in the three remaining polio-endemic WHO regions (African Region, Eastern Mediterranean Region, and South-East Asia Region). Even in polio-endemic regions, many countries are already polio free as the geographic extent of poliovirus shrinks while others. especially those experiencing conflict and war, pose substantial challenges to implementing the proven polio eradication strategies. Increasing attention and research now are devoted to the certification of polio eradication in the polio-free regions (that will include the first phase of implementing the Global Plan of Action for the laboratory containment of wild poliovirus) and formulating a policy for stopping all polio vaccination once eradication, containment, and global certification have been achieved. This report outlines the progress toward polio eradication and highlights some of the remaining issues and challenges that must be addressed before polio becomes a disease that future generations know only by history.

Poliovirus vaccines. Progress toward global poliomyelitis eradication and changing routine immunization recommendations in the United States.

Poliomyelitis prevention in the United States has relied virtually exclusively on OPV during the past 30 years. Starting in 1997, a major change in the poliomyelitis vaccination policy occurred, facilitated by substantial progress toward worldwide poliomyelitis eradication. A sequential schedule of IPV followed by OPV became the preferred means to prevent poliomyelitis, although an all-OPV and an all-IPV schedule were considered acceptable alternatives. In 1999, two doses of IPV were recommended to start the primary series, followed by two doses of either poliovirus vaccine. As of January 2000, an all-IPV schedule is currently being implemented in the United States for routine childhood vaccination. Several unusual features are associated with the major public health policy change from an all-OPV to a sequential schedule, including (1) the process of involving a neutral party (i.e., the IOM); (2) the perceived concerns expressed before the change in policy with regard to provider and parent compliance, which could affect the hard-earned gains in raising immunization coverage rates; (3) the ethical issues surrounding the change (e.g., societal versus individual protection) and the influence that a single case of VAPP may have on national policy; (4) the relative lack of importance of cost-effectiveness data; and (5) the weight of progress in the global polio eradication initiative spurring the change in the United States and, increasingly, in other industrialized countries. The IOM assisted in the evaluation of the national poliomyelitis vaccination policy in 1977 and again in 1988. The 1988 review recommended that a sequential IPV-OPV schedule be considered at such time that a combination vaccine becomes available. Also, the IOM raised several important questions. Extensive research to address the questions raised by the IOM had been conducted so that, in 1996, more data were available for the decision-making process. The primary reasons for the change in vaccination policy were (1) the continued occurrence of VAPP in the absence of indigenously acquired wildtype poliovirus-associated paralytic disease, (2) the reduced risk for importation and spread of wild-type poliovirus caused by the progress of the global polio eradication initiative, (3) evidence from vaccine trials that combined IPV-OPV schedules are safe and immunogenic, and (4) maintenance of high levels of population immunity to poliovirus. The global effect of a national change in poliomyelitis vaccination policy was also considered in this policy-making process. Some members of the public health and medical communities raised objections that an increased reliance on IPV in the United States could lead other countries, especially developing countries, to inappropriately abandon OPV and increase reliance on IPV for routine vaccination. Experience from the global smallpox eradication campaign indicated that this scenario was unlikely. The United States ceased vaccinating against smallpox in 1971, 6 years before smallpox was eliminated from the world, without jeopardizing the global smallpox campaign. Subsequently, the effect on the global eradication initiative has been negligible. This article illustrates the potential discrepancy between expressed theoretic concerns about the number of injections and the actual practice once vaccination policy recommendations become the standard of care and that appropriate training and education can overcome these initial concerns. The authors found that compliance with the recommended use of IPV for the first and second doses as part of the sequential schedule was high, independent of socioeconomic status and ethnicity. The need for additional injections did not present a barrier to completion of the recommended childhood immunization schedule. (ABSTRACT TRUNCATED)

Possible global strategies for stopping polio vaccination and how they could be harmonized.

One of the challenges of the polio eradication initiative over the next few years will be the formulation of an optimal strategy for stopping poliovirus vaccination after global certification of polio eradication has been accomplished. This strategy must maximize the benefits and minimize the risks. A number of strategies are currently under consideration, including: (i) synchronized global discontinuation of use of oral poliovirus vaccine (OPV); (ii) regional or subregional coordinated OPV discontinuation; and (iii) moving from trivalent to bivalent or monovalent OPV. Other options include moving from OPV to global use of IPV for an interim period before cessation of IPV use (to eliminate circulation of vaccine-derived poliovirus, if necessary) or development of new OPV strains that are not transmissible. Each of these strategies is associated with specific advantages (financial benefits for OPV discontinuation) and disadvantages (cost of switch to IPV) and inherent uncertainties (risk of continued poliovirus circulation in certain populations or prolonged virus replication in immunodeficient persons). An ambitious research agenda addresses the remaining questions and issues. Nevertheless, several generalities are already clear. Unprecedented collaboration between countries, regions, and indeed the entire world will be required to implement a global OPV discontinuation strategy Regulatory approval will be needed for an interim bivalent OPV or for monovalent OPV in many countries. Manufacturers will need sufficient lead time to produce sufficient quantities of IPV Finally, the financial implications for any of these strategies need to be considered. Whatever strategy is followed it will be necessary to stockpile supplies of a poliovirus-containing vaccine (most probably all three types of monovalent OPV), and to develop contingency plans to respond should an outbreak of polio occur after stopping vaccination.

Current epidemiology of pertussis in the United States.

The incidence of pertussis in the United States decreased rapidly during the 20th century, with the most impressive decreases resulting from the widespread use of DTP vaccine since the late 1940's. As a result of immunization laws, vaccine coverage levels against pertussis at school entry have been greater than 95% since 1980. National surveillance for pertussis done by the Centers for Disease Control (CDC) consists of two parts: a weekly telephone reporting system and a written case report system providing more detailed demographic, clinical, and laboratory information. In addition, data on secondary spread of pertussis among household contacts of reported cases were available on a small proportion of reported cases during 1979-1983. During the period 1980-1986, a total of 17,396 cases of pertussis was reported to CDC by weekly telephone reports. The annual incidence of reported pertussis rose during this period from 0.5 cases per 100,000 population to 1.7/100,000. Infants less than 12 months of age had the highest average annual incidence, estimated at 32 cases per 100,000. Children 1-4 years of age accounted for 25% of all cases but had an average annual incidence only 1/7th that of infants. The incidence rates for all age groups increased consistently between 1982 and 1986. The most impressive relative increases occurred among older adolescents and persons 20 years of age and older. In 1986, 10% of reported cases were in this age group compared to only 5% in 1982. Rates of hospitalization and complications such as pneumonia, seizures, and encephalopathy associated with pertussis were highest in children less than 6 months of age and declined progressively with increasing age.(ABSTRACT TRUNCATED AT 250 WORDS)

Vaccine prevention of Haemophilus influenzae type b disease: past, present and future.

In little more than half a century we have come a long way toward the eventual elimination of invasive Hib disease as a major threat to children in the United States. The Haemophilus b polysaccharide vaccine has provided the first tool for large scale public health intervention efforts in specific target groups of children older than 18 months of age who are likely to benefit from immunization. Immunization programs using the currently available vaccine represent an interim measure that is likely to be replaced within the next few years by new programs utilizing an improved vaccine with greater potential for preventing invasive Hib disease in susceptible infants and young children. Prospects appear good that an improved second generation vaccine that will provide protective efficacy in infants during the first year of life will become available in the near future.

Pertussis hospitalizations and mortality in the United States, 1985-1988. Evaluation of the completeness of national reporting.

OBJECTIVE: --To determine the magnitude of hospitalizations for pertussis and pertussis mortality and to estimate the total burden of clinically significant pertussis in the United States. DESIGN: --Capture-recapture methods for estimating population size from independent surveillance systems were used to analyze morbidity and mortality data from case report forms received at the Centers for Disease Control (CDC) from the states, and compared these data with pertussis hospitalizations compiled from a database of US hospitals participating in the Commission on Professional and Hospital Activities-Professional Activities Survey (CPHA-PAS) and death certificate reports compiled by the National Center for Health Statistics (NCHS). POPULATION STUDIED: --All pertussis hospitalizations and pertussis-related deaths in the United States, 1985 through 1988. RESULTS: --We estimated that 13,557 pertussis hospitalizations (95% confidence interval [CI], 12,953 to 14,162) and 98 pertussis deaths had occurred during the 4-year study period (an average of more than 3300 hospitalizations and 25 deaths per year). The completeness of reporting hospitalizations to the CDC was 32% and to the CPHA-PAS, 23%, while the completeness of reporting pertussis deaths to the CDC was 33% and to NCHS, 23%. Patients who were hospitalized with pertussis and reported to CDC were at a higher risk for developing pneumonia (31.0% vs 20.0%, relative risk [RR], 1.6; 95% CI, 1.4 to 1.7), seizures (3.7% vs 2.1%; RR, 1.9; 95% CI, 1.4 to 2.5) and encephalitis (1.2% vs 0.2%; RR, 5.3; 95% CI, 2.4 to 11.6) compared with patients recorded in the CPHA-PAS system. CONCLUSIONS: --Our study suggests that there is substantial underreporting of pertussis, that severe complications of pertussis (including hospitalizations) are reported preferentially to the CDC, and that the national health impact of pertussis based on these indicators is considerably higher than previously published reports have suggested.

Perspectives on the relative resurgence of mumps in the United States.

Although the United States has enjoyed great success in the control of mumps since the licensure of live virus mumps vaccine in 1967, a relative resurgence of mumps during the 1986-1987 period has raised concerns about the long-term effectiveness of mumps vaccine. We received mumps surveillance data, historical information on mumps vaccine distribution and recommendations for its use, survey data on levels of mumps immunization in US children during the 1973-1985 period, the effect of mumps immunization school laws on the reported incidence of mumps among states with and without such laws, and studies of mumps vaccine effectiveness. Following licensure, a decade elapsed before mumps vaccine was endorsed as a routine immunization of childhood, while immunization survey and vaccine distribution data reflected only gradual acceptance of the vaccine. However, mumps incidence declined during this period, resulting in a relatively underimmunized cohort of children born between 1967 and 1977 who grew up during a period when the risk of exposure to mumps was rapidly declining. The resurgence of mumps since 1986 has been characterized by a selective increase in incidence and a shift in the age group at highest risk to middle and high school students in those states lacking comprehensive mumps immunization school laws. Postlicensure field evaluations of mumps vaccine effectiveness have not demonstrated waning vaccine-induced immunity. The data indicate that the relative resurgence of mumps in the United States is chiefly due to a failure to vaccinate all susceptible persons, especially those who are now between 10 and 19 years old. Mumps immunization school laws offer an approach to deal with the problem of continuing susceptibility in school-age populations.