Diphtheria in Estonia, 1991-1996

Clinical diphtheria reappeared in Estonia in 1991. Between 1991 and 1996, 61 cases and 5 deaths occurred; 19 cases were among children 5-9 years of age, and 11 were among persons 40-49 years of age. From 1993-1995, vaccine supplies donated by Finland were used in vaccination programs. In 1995, the International Federation of Red Cross and Red Crescent Societies and the Estonian Red Cross launched a mass vaccination campaign targeting the adult population. By the end of 1997, it was estimated that 46% of adults had received at least one dose of vaccine. Although the vaccination campaigns did not target the pediatric population, vaccination coverage in school-aged children remained high due to continuing routine vaccination programs. The reappearance and epidemic of clinical diphtheria cases and the mass vaccination campaign efforts demonstrated that preventive measures are important and must be maintained in order to keep diphtheria under control.     

Epidemic diphtheria in the Kyrgyz Republic, 1994-1998

The Kyrgyz Republic experienced a widespread diphtheria epidemic during 1994-1998. National diphtheria surveillance and vaccination coverage information were used to describe the course of the epidemic. The epidemic began in August 1994, reached a peak in 1995 with 704 cases (incidence rate: 15.4/100,000 population) and 30 deaths, and declined to an incidence rate of 4.0/100,000 during the first 8 months of 1998. Age-specific incidence was highest in 1995 among persons 15-19 and 20-29 years old. Three rounds of mass vaccination with tetanus and diphtheria toxoids for adult use (Td) were conducted; reported coverage was 69% in 1995 and >95% in 1996 and 1997. Reported routine vaccination coverage with three doses of diphtheria toxoid by age 12 months increased from 62% in 1989 to 98% in 1997. Mass vaccination of the adult population with Td and improvements in childhood vaccination coverage played a major role in controlling the epidemic.     

Epidemic diphtheria in Belarus, 1992-1997

In 1990, epidemic diphtheria reemerged in Russia and spread to Belarus in 1992, when 66 cases were reported. Diphtheria cases doubled each year in 1993 and 1994 and peaked in 1995, when 322 cases were reported. Intensified routine immunization of young children and mass vaccination of older children and selected groups of adults were conducted in 1995 and were followed by mass vaccination campaigns targeting all adults in 1996. By the end of 1996, full immunization of >95% of children and coverage of>87% of adults with >/=1 dose resulted in a rapid decline in diphtheria cases. In 1998, only 36 cases of diphtheria were reported. More than 70% of the 965 cases and 26 fatalities reported during 1990-1998 occurred among persons >14 years of age. High levels of immunity among the entire population are needed for rapid control of diphtheria epidemics in the vaccine era.     

Diphtheria epidemic in the Republic of Georgia, 1993-1997

Epidemic diphtheria reemerged in the republic of Georgia in 1993. From 1993 to 1997, 1405 cases were reported (28 in 1993, 312 in 1994, 429 in 1995, 348 in 1996, and 288 in 1997), with a cumulative incidence of 25.8/100,000 and a case fatality ratio of 9.5%. During 1993-1997, 53% of the diphtheria cases occurred among persons >/=15 years of age. Unvaccinated patients were more likely to have toxic forms (relative risk=2.24; 95% confidence interval=1.69-2.96) or to die of diphtheria (relative risk=2.24; 95% confidence interval=1. 36-3.68) than those who had received at least one dose of diphtheria toxoid. Improvement in routine childhood vaccination coverage and implementation of mass adult vaccination campaigns have been critical to bringing the epidemic under control. By mid-1998, the overall diphtheria situation in Georgia appeared to have been controlled. Only 53 cases were reported from January to June 1998, representing a 64% decrease from the 148 cases during the corresponding period in 1997.     

Impact of Non-routine Vaccination on the Incidence of Invasive Haemophilus influenzae Type b (Hib) Disease: Experience in the Autonomous Region of Valencia, Spain

OBJECTIVE: This study assessed the impact of non-routine vaccination against invasive Haemophilus influenzae (Hib)disease before the introduction of universal childhood Hib vaccination. METHODS: Data were obtained from a prospective surveillance program for invasive bacterial diseases in children <15 years of age that was begun in the Autonomous Region of Valencia on 1 December 1995. RESULTS: An incidence of 15.5 cases of invasive Hib disease per 100,000 children <5 years of age was reported in the first year of the surveillance program (from 1 December 1995 to 30 November 1996), when Hib vaccination coverage was estimated to be 32.5%. An increase in vaccination coverage to 44% in the second year (1 December 1996 to 30 November 1997) was associated with a reduction in disease incidence to 3.3 cases per 100,000. After the initiation of universal vaccination in December 1998, only two cases were reported. The effectiveness of non-routine vaccination was 71% in 1997. CONCLUSIONS: These results show that before the introduction of routine childhood Hib vaccination, widespread use of the vaccine can dramatically reduce the occurrence of invasive Hib disease.     

Measles in Mexico, 1941-2001: interruption of endemic transmission and lessons learned

In Mexico, measles occurred in a cyclical endemic-epidemic pattern until the early 1970s. Beginning in 1973, routine vaccination augmented by mass vaccination campaigns led to a decrease in the incidence of measles until the 1989-1990 regional pandemic, when the measles attack rate rose to 80 cases per 100000, resulting in 5899 deaths. Since the pandemic, measles elimination efforts in Mexico have resulted in increasing coverage to >95% among children aged 1-6 years with 2 doses of either measles or measles-mumps-rubella vaccine since 1996 and in coverage of 97.6% among children aged 6-10 since 1999. Surveillance data suggest that the transmission of indigenous measles virus was interrupted in 1997. After almost 4 years without measles cases, in April 2000, measles virus was reintroduced into Mexico and 30 laboratory-confirmed cases were reported. Detection of relatively few cases in nonprogrammatic age groups affirms the high immunization coverage and the sensitivity of measles surveillance in Mexico. We conclude that the specific strategies adopted for measles elimination have enabled Mexico to eliminate the endemic transmission of measles.     

Epidemic diphtheria in the 1990s: Azerbaijan

The diphtheria epidemic in the former Soviet Union reached Azerbaijan in 1991, when 66 cases of diphtheria were reported, a number that compared with 4 cases in 1990. From 1990-1996, 2182 cases of diphtheria and 286 diphtheria fatalities (case fatality rate: 13.1%) were reported in Azerbaijan, primarily among persons 5-39 years of age. Almost 45% of cases and 61% of deaths occurred among children 5-14 years of age. The high burden of severe disease among children and young adults suggested a different pattern of preexisting immunity against diphtheria in the Azerbaijani population than was observed in the concurrent diphtheria epidemic in Russia. Because resources were limited in Azerbaijan, mass immunization of the population was carried out in stages, focusing initially on school-aged children. Mass immunization campaigns targeting children were moderately successful in stabilizing the epidemic; mass immunization campaigns targeting both adults and children were eventually needed to fully stop the epidemic.     

Universal influenza vaccination in the United States: are we ready? Report of a meeting

Universal influenza vaccination has been proposed as one strategy to improve vaccination coverage and disease prevention. In October 2005, influenza and vaccination experts, public health practitioners, representatives from medical professional societies, influenza vaccine manufacturers, and managed care organizations met to assess whether current data were sufficient to support an expansion of universal influenza vaccination and to define information gaps and potential barriers to implementation. Presenters at the meeting documented the substantial burden of influenza disease among all age groups, the major role of children in transmission, and the effectiveness of vaccine, especially in healthy children and adults. Observational studies and a mathematical model suggested that indirect protection, or "herd immunity," resulting from vaccination of school-age children would substantially reduce the incidence of disease in other age groups. Economic analyses generally showed that vaccination of healthy children and adults is cost-effective and is sensitive to vaccine cost, population group, and season. Influenza vaccination received annually over several years is safe and effective, but data on long-term use are limited. Challenges to expanded recommendations include maintenance of the vaccine supply, implementation of a feasible and effective strategy for vaccine delivery, the burden on the public health infrastructure, public acceptability, and financing. Overall, meeting attendees favored incremental expansion of recommendations, potentially toward universal influenza vaccination. They preferred to expand recommendations among children first, because children have a higher risk of illness, compared with healthy adults; because there is greater feasibility of implementation of the recommendations among children; and because of the potential for herd immunity decreasing morbidity and mortality among adults.     

Diphtheria toxoid vaccine effectiveness: A case-control study in Russia

Prior to the completion of this and other studies, low effectiveness of diphtheria toxoid-containing vaccine was suspected to be a major contributing factor to the diphtheria epidemic that began in the Russian Federation in 1990. A vaccine effectiveness study was done in Moscow by enrolling physician-diagnosed cases and 10 control subjects per case. Controls were matched to cases by age (+/-3 months) and clinic registration. Vaccination history was abstracted from a standardized form for case-patients and from clinic vaccination records for control subjects. Two hundred seventeen case-patients and 2169 matched controls were included in the study. Most controls (92%) had received three or more doses of a diphtheria toxoid vaccine, compared with 72% of case-patients. The vaccine effectiveness for three or more doses was 97% (95% confidence interval: 94.3-98.4). Low vaccine effectiveness was not a contributing factor to the diphtheria epidemic in the Russian Federation. To control and prevent diphtheria epidemics, it is necessary to achieve and maintain high vaccination coverage with three or more doses of diphtheria toxoid among adults and children.     

Epidemiological pattern of meningococcal disease in Valencia, Spain. Impact of a mass immunization campaign with meningococcal C polysaccharide vaccine

The objective of this study was to define the epidemiological pattern of meningococcal disease in the autonomous region of Valencia, Spain, and the impact of a mass immunization campaign against serogroup C meningococcus. Data were obtained from a prospective surveillance program for invasive bacterial diseases in children < 15 y of age that began in the Valencia region on 1 December, 1995. During the period 1996-98, 213 cases of meningococcal disease were detected, representing an annual incidence of 11.3/100,000 children < 15 y. Serogroup C accounted for 31% and 38.5% of cases in 1996 and 1997, respectively (annual incidences of 2.9 and 5.4 cases/100,000 children < 15 y). An immunization campaign with the meningococcal C polysaccharide vaccine, which included all persons between 18 months and 19 y of age, began in late 1997 (vaccination coverage of 86%). In 1998, the annual incidence of meningococcal C disease fell to 1.4 cases per 100,000 children < 15 y of age. These results mirror the increase in the reported incidence of serogroup C meningococcal disease in Spain in the 1990s, a trend that was reversed after the introduction of the mass vaccination campaign. Meningococcal polysaccharide vaccine seems to be an effective public health tool for the management of this serious communicable disease.     

Ukraine, 1992: first assessment of diphtheria vaccine effectiveness during the recent resurgence of diphtheria in the Former Soviet Union

A case-control study in Ukraine provided the first data on the field effectiveness of Russian-produced vaccine during the 1990 diphtheria resurgence in the former Soviet Union. For each of 262 diphtheria cases <15 years of age who were reported from January through October 1992, 2 controls, matched by age and clinic, were selected. The effectiveness of three doses of diphtheria vaccine was 98.2% (95% confidence interval: 90.3-99.9). Among controls, 84% had received three or more vaccinations by 2 years of age. These results suggest that the following five hypothesized causes of the outbreak appeared unlikely: appearance of a new "mutant" diphtheria strain, low potency of the Russian-produced diphtheria vaccine, inadequate cold chain, poor host immunogenicity due to radiation exposure from Chernobyl, and low routine childhood vaccination coverage. It is concluded that initial priority for scarce resources for controlling this outbreak should be placed on vaccination of persons susceptible to diphtheria (e.g., adults) rather than revaccination of children.     

Pneumococcal vaccination in adults

Pneumococci remain the most common etiology of community-acquired pneumonia in adults, with significant attendant mortality in the elderly. With the recognition of increasing rates of drug-resistant Streptococcus pneumoniae in recent years, efforts to prevent disease through vaccination have gained greater impetus. The 23-valent pneumococcal vaccine is used widely in the United States and provides effective protection against bacteremic pneumococcal disease, particularly in the immunocompetent host. The 7-valent pneumococcal conjugate vaccine, licensed in the United States in 2000, has had a dramatic impact on pneumococcal disease in the pediatric population, and its use in children has had effects on incidence rates in nonimmunized adults as well. Future directions include efforts to improve vaccination coverage in targeted populations and the development of more immunogenic and efficacious vaccines for high-risk groups.     

Influenza vaccination of persons with cardiovascular disease in the United States

People who have cardiovascular disease are at increased risk of hospitalization or death associated with influenza infection, and are included among the high-risk groups for whom annual influenza vaccination is recommended. To measure the progress toward the national year 2000 and 2010 objectives of a 60% annual influenza vaccination of adults with high-risk conditions aged 18 to 64 years, we analyzed data from the 1997 to 2001 National Health Interview Surveys (NHIS) regarding persons with cardiovascular disease. The NHIS is an annual, cross-sectional survey representative of the U.S., noninstitutionalized, civilian population. Estimated percentages of persons with heart disease reporting influenza vaccination were relatively stable during the 1996-97 through 2000-2001 influenza seasons, with the highest levels in most groups occurring in 1999-2000: 49.2% (95% confidence interval [CI], 44.1%-54.3%) among persons aged 50 to 64 years; and 22.7% (95% CI, 18.2%-27.2%) among persons aged 18 to 49 years. Influenza vaccine coverage among adults aged 18 to 64 years with cardiovascular disease is substantially below the national objective. Multiple strategies are needed to improve vaccination coverage, such as increasing the awareness of and demand for vaccination by persons with heart disease; increasing implementation by providers of practices that have been shown to increase vaccination levels; and adopting of influenza vaccination by primary care providers and specialists as a standard of care for persons diagnosed with cardiovascular disease.     

Long-term trends in hepatitis A incidence following the inclusion of Hepatitis A vaccine in the routine nationwide immunization program

Summary.  For many years hepatitis A was one of the most common vaccine preventable diseases in Israel. In 1999, Israel became the first country to introduce an inactivated hepatitis A vaccine into its national childhood vaccination program. The objectives of the present study were to study trends in disease incidence after the implementation of the new vaccination policy and to assess vaccination coverage among children and adults in Israel. We used the databases of the second largest HMO in Israel (1.7 million members) to identify patients who had evidence of hepatitis A in 1998 and 2007 and to collect information on all subjects who received at least one dose of hepatitis A vaccine during the study period. Hepatitis A vaccination coverage in children <5 years and 5–14 years of age increased from 9% and 15% in 1998 to 89% and 68% in 2007, respectively. During this period the annual incidence of hepatitis A dropped from 142.4 per to 7.6 per 100 000. The most prominent reduction in the age-specific annual incidence rates was calculated in children <5 years from 239.4 per 100 000 in 1998 to 2.2 per 100 000 in 2007 and from 310.3 per 100 000 to 3.0 per 100 000 in children aged 5–14 years. In endemic areas, vaccination of infants and children against hepatitis A can greatly reduce the total burden of the disease.     

Epidemic diphtheria in the Republic of Georgia, 1993-1996: risk factors for fatal outcome among hospitalized patients

Epidemic diphtheria reemerged in the republic of Georgia in November 1993. To identify risk factors for fatal outcomes, clinical and epidemiologic data on all hospitalized diphtheria patients were examined. Medical charts of patients from 1993-1995 were reviewed. A total of 659 cases and 68 deaths were identified (case fatality rate [CFR] = 10.3%). Fifty-two percent of all cases and 68% of deaths were in children 3 days) between onset of symptoms to antitoxin treatment were significantly associated with fatal outcomes. Immunization of children and 40- to 49-year-old adults was required to rapidly control the epidemic.     

Contraindications to vaccination in the Russian Federation

Failure to achieve high levels of immunity among children contributed to the epidemic of diphtheria that occurred in the Russian Federation during the 1990s. A major factor in this failure was the extensive list of contraindications to vaccination that was in use throughout the countries of the former Soviet Union. In 1980, the Ministry of Health (MOH) of the Soviet Union adopted an extensive list of contraindications for use of the diphtheria-tetanus toxoids-pertussis (DTP) vaccine. In 1994, the MOH of the Russian Federation revised the list of contraindications to vaccination to be largely in accord with World Health Organization recommendations. Since then, age-appropriate vaccination coverage has increased markedly: In 1996, DTP3 coverage among children 12 months of age had increased to 87% from 60% in 1990.     

Diphtheria in Lithuania, 1986-1996

Diphtheria reappeared in Lithuania in 1986 and rose to epidemic levels by 1992. Between 1991 and 1996, 110 cases of diphtheria were registered, with an incidence of 0.03-1.15/100,000 population. Most cases (84%) and all 17 deaths occurred among persons >/=15 years, most of whom had never been vaccinated. Persons 40-49 years old had the highest average annual age-specific morbidity (1.70/100,000) and mortality (0.53/100,000) rates. Low levels of immunity among individuals 40-49 years old and migration to epidemic areas in Russia and Belarus contributed to the epidemic's occurrence. Between 1991 and 1995, toxigenic Corynebacterium diphtheriae strains were isolated from 84 of all registered patients (76%), and nontoxigenic strains were isolated from 13 (12%). By 1996, two mass vaccination campaigns, which provided one dose of vaccine to individuals 25-30 years old and three doses of vaccine to persons 31-60 years old, helped reduce the number of cases. The first campaign achieved 69% coverage; the second achieved 48% coverage.     

Diphtheria in the Russian Federation in the 1990s

A resurgence of diphtheria spread throughout the Russian Federation in the early 1990s; diphtheria had been well controlled, but circulation of toxigenic strains of Corynebacterium diphtheriae had persisted since the implementation of universal childhood vaccination in the late 1950s. More than 115,000 cases and 3,000 deaths were reported from 1990 to 1997, and, in contrast to the situation in the prevaccine era, most of the cases and deaths occurred among adults. Contributing factors included the accumulation of susceptible individuals among both adults and children and probably the introduction of new strains of C. diphtheriae. Vaccine quality, vaccine supply, or access to vaccine providers did not significantly contribute to the epidemic. Mass vaccination of adults and improved childhood immunization controlled the epidemic. High levels of population immunity, especially among children, will be needed to prevent and control similar outbreaks in the future.     

Successful control and impending elimination of measles in the Islamic Republic of Iran

Measles is still one of the most common infectious killers of children in the world, especially in developing countries. In Iran, during the prevaccine era, 150,000-500,000 cases of measles were reported annually, with a death rate of 10%-15%. After the establishment of Expanded Program on Immunization program in 1984, vaccination rates for the first and second doses of measles vaccine increased to >90% by the mid-1990s, and the number of measles cases decreased to 2652 in 1996. In response to increased numbers of cases in older age groups during 1996-2002, a nationwide measles-rubella vaccination campaign was conducted in 2003, and 33,100,000 persons (99%) aged 5-25 years were vaccinated. During 2004-2009, 221 laboratory-confirmed measles cases (<1 case per million population) were detected, primarily in rural areas and among migrant groups who traveled to or came from high-incidence countries. High routine immunization coverage, low disease incidence, and surveillance system data suggest that interruption of endemic virus transmission might have already been achieved in Iran, but challenges remain and continued efforts are needed to sustain this accomplishment.     

Experience with the new German hepatitis B vaccination strategy since 1995

In Germany general hepatitis B (HB) vaccination for newborns and adolescents was introduced in all federal states following the recommendation of the STIKO (Permanent Vaccination Commission) of 1995. In 1998 serological studies of the German National Health Survey showed that at least 9.8% in the age group of 18 to 19 years had been vaccinated against HBV infection. By 1996 the vaccine doses sold for children rose dramatically and started to reach a plateau of approximately five million per year in 1997. Data from the kassen?rztliche Vereinigung of the Oberpfalz region in Bavaria also indicate that the new policy started to be implemented in 1996. At school entry, however, in 1997 only 10% of the children in seven West German states showed serological evidence of HB vaccination coverage. According to observations of virologists, paediatricians and public health experts the current acceptance of the HB vaccination recommendations is 80%-90% in children below the age of six years but only 30% to 40% in adolescents. To achieve high HB vaccination coverage rates in Germany more rapidly a modern surveillance system providing detailed data about vaccination coverage in the different age and population groups is needed. Based on those data additional targeted vaccination strategies for those that can only be contacted by the traditional health care system, such as teenagers and vulnerable groups, should be developed, involving the public health service, local communities and other agencies.