Low Incidence Of Measles Research Articles

Measles and Rubella Elimination in the Western Pacific Region in 2013-2022: Lessons Learned from Progress and Achievements Made during Regional and Global Measles Resurgences.

Measles is the most contagious communicable disease, causing an estimated 5.5 million cases and more than 30,000 deaths in the Western Pacific Region (WPR) during 2000. Rubella infection in a pregnant woman can be devastating for the foetus, resulting in congenital rubella syndrome (CRS) in 90% of rubella infections in early pregnancy. It was estimated that approximately 9000 CRS cases occurred in the WPR in 2010. World Health Organization (WHO) Member States in the WPR decided in 2003 to eliminate measles and in 2014 to eliminate rubella from the region. While the WPR successfully attained historically low measles incidence in 2012, it experienced a region-wide measles resurgence in 2013-2016. During the regional resurgence, WHO and Member States accumulated greater knowledge on the epidemiology of measles and rubella in the WPR and strategies to maintain gains. The implementation of the resulting new regional strategy and plan of action from 2018 has proven that measles and rubella elimination is achievable and sustainable under the pressure of multiple importations of measles virus during the world-wide measles resurgences in 2018-2019. This article discusses this progress and achievements towards achieving the global eradication of measles and rubella.

Achieving measles elimination and emerging modified measles: Longitudinal measles epidemiology from 1982 to 2021 in Osaka Prefecture, Japan

BackgroundMeasles is a contagious viral disease causing infant mortality in developing countries without vaccination programs. In Japan, measles vaccination was launched in 1978, surveillance commenced in 1981, and elimination was achieved in 2015. This was due to improved, legally required surveillance methods and vaccine programs. MethodsThe data sets of sentinel (1982–2007) and notifiable (2008–2021) disease surveillance, as well as the vaccination coverage, detected genotypes, and seroepidemiology during the study period in Osaka Prefecture, were analyzed. Additionally, the trend under the current notifiable surveillance was compared before (2008–2014) and after (2015–2021) measles elimination. ResultsUnder sentinel surveillance, 51,107 cases were reported, predominantly infants aged 1–4 years (63.6 %). Under notifiable disease surveillance, the 781 patients were predominantly in their 20s–30s (43.7 %). From 2000, the age of the major susceptible group increased due to the rise in vaccination coverage, which exceeded 95% for the first dose in 1998 and 90% for the second dose in 2009. Consistent with these data, seroprevalence exceeded 95% in 2011. However, the geometric mean of the antibody titer showed a decreasing trend with a falling number of patients. Compared with before and after measles elimination, the number of modified measles cases increased from 10.1% to 48.2%. During the study period, 398 strains comprising eight genotypes were identified, and the dominant type changed over time. After measles elimination, genotypes B3 and D8, derived from imported cases, became predominant. ConclusionsImproved vaccination coverage and surveillance reduced measles cases and increased herd immunity. However, the lack of a booster effect due to the low incidence of measles caused waning antibody titers despite high seroprevalence, which may contribute to the rising rate of vaccine failures causing modified measles. Careful monitoring of measles incidence and herd immunity are necessary for measles eradication.

Australian vaccine preventable disease epidemiological review series: measles, 2012-2019.

Data sources, relevant to measles epidemiology from 2012 to 2019, were reviewed in the context of Australia's certification, by the World Health Organization in 2014, of the elimination of measles. Data on measles notifications, hospitalisations, and deaths were obtained from the National Notifiable Diseases Surveillance System, the National Hospital Morbidity Database, and the Australian Coordinating Registry. Data were analysed by age group, state/territory, Aboriginal and Torres Strait Islander status, genotype, place of acquisition, source of infection (importation status), and vaccination status. Between 2012 and 2019, there were 1,337 measles notifications (average annual notifications 0.7 per 100,000 population per year) and 425 hospitalisations with measles as principal diagnosis (0.3 per 100,000 population per year) were recorded. The highest annual notification rate was in 2014, when the rate in the Northern Territory was 21.4 per 100,000 population per year. Although notification and hospitalisation rates were highest in infants < 12 months (respectively 5.8 and 2.1 per 100,000 population per year), people aged 10 to 39 years (10-19y: 272 notifications; 20-29y: 347; 30-39y: 266) accounted for 66% of notified cases. Of cases with a known vaccination status, only 20/169 (11.8%) of those aged 1-9 years had received at least one dose of measles-containing vaccine, compared with 215/571 (37.7%) of those aged 10-39 years. Persons born before 1966 (at least 47 years of age during the study period) are likely to have immunity from wild-type measles infection and had the lowest notification rates in each year. Of notified cases, 98.1% were imported or import related, and of the 900 measles viruses genotyped, D8 and B3 accounted for 89.1%. This review's findings of low measles incidence, in the presence of robust surveillance and high two-dose measles vaccination coverage, provide evidence of continued elimination of endemic measles in Australia, with almost all cases imported or epidemiologically linked to an imported case. Most cases eligible for vaccination are unvaccinated, which should remain the primary focus for prevention. Potential waning immunity in older age groups requires monitoring. Continued high population immunity and high-quality public health response to cases will be needed to maintain Australia's elimination status, particularly once international borders reopen.

COVID-19 Australia: Epidemiology Report 60: Reporting period ending 10 April 2022.

Background Data sources, relevant to measles epidemiology from 2012 to 2019, were reviewed in the context of Australia’s certification, by the World Health Organization in 2014, of the elimination of measles. Methods Data on measles notifications, hospitalisations, and deaths were obtained from the National Notifiable Diseases Surveillance System, the National Hospital Morbidity Database, and the Australian Coordinating Registry. Data were analysed by age group, state/territory, Aboriginal and Torres Strait Islander status, genotype, place of acquisition, source of infection (importation status), and vaccination status. Results Between 2012 and 2019, there were 1,337 measles notifications (average annual notifications 0.7 per 100,000 population per year) and 425 hospitalisations with measles as principal diagnosis (0.3 per 100,000 population per year) were recorded. The highest annual notification rate was in 2014, when the rate in the Northern Territory was 21.4 per 100,000 population per year. Although notification and hospitalisation rates were highest in infants &lt; 12 months (respectively 5.8 and 2.1 per 100,000 population per year), people aged 10 to 39 years (10–19y: 272 notifications; 20–29y: 347; 30–39y: 266) accounted for 66% of notified cases. Of cases with a known vaccination status, only 20/169 (11.8%) of those aged 1–9 years had received at least one dose of measles-containing vaccine, compared with 215/571 (37.7%) of those aged 10–39 years. Persons born before 1966 (at least 47 years of age during the study period) are likely to have immunity from wild-type measles infection and had the lowest notification rates in each year. Of notified cases, 98.1% were imported or import related, and of the 900 measles viruses genotyped, D8 and B3 accounted for 89.1%. Conclusion This review’s findings of low measles incidence, in the presence of robust surveillance and high two-dose measles vaccination coverage, provide evidence of continued elimination of endemic measles in Australia, with almost all cases imported or epidemiologically linked to an imported case. Most cases eligible for vaccination are unvaccinated, which should remain the primary focus for prevention. Potential waning immunity in older age groups requires monitoring. Continued high population immunity and high-quality public health response to cases will be needed to maintain Australia’s elimination status, particularly once international borders reopen.

Impact on Epidemic Measles of Vaccination Campaigns Triggered by Disease Outbreaks or Serosurveys: A Modeling Study.

BackgroundRoutine vaccination supplemented by planned campaigns occurring at 2–5 y intervals is the core of current measles control and elimination efforts. Yet, large, unexpected outbreaks still occur, even when control measures appear effective. Supplementing these activities with mass vaccination campaigns triggered when low levels of measles immunity are observed in a sample of the population (i.e., serosurveys) or incident measles cases occur may provide a way to limit the size of outbreaks.Methods and FindingsMeasles incidence was simulated using stochastic age-structured epidemic models in settings conducive to high or low measles incidence, roughly reflecting demographic contexts and measles vaccination coverage of four heterogeneous countries: Nepal, Niger, Yemen, and Zambia. Uncertainty in underlying vaccination rates was modeled. Scenarios with case- or serosurvey-triggered campaigns reaching 20% of the susceptible population were compared to scenarios without triggered campaigns. The best performing of the tested case-triggered campaigns prevent an average of 28,613 (95% CI 25,722–31,505) cases over 15 y in our highest incidence setting and 599 (95% CI 464–735) cases in the lowest incidence setting. Serosurvey-triggered campaigns can prevent 89,173 (95% CI, 86,768–91,577) and 744 (612–876) cases, respectively, but are triggered yearly in high-incidence settings. Triggered campaigns reduce the highest cumulative incidence seen in simulations by up to 80%. While the scenarios considered in this strategic modeling exercise are reflective of real populations, the exact quantitative interpretation of the results is limited by the simplifications in country structure, vaccination policy, and surveillance system performance. Careful investigation into the cost-effectiveness in different contexts would be essential before moving forward with implementation.ConclusionsSerologically triggered campaigns could help prevent severe epidemics in the face of epidemiological and vaccination uncertainty. Hence, small-scale serology may serve as the basis for effective adaptive public health strategies, although, in high-incidence settings, case-triggered approaches are likely more efficient.

The impact of supplementary immunization activities on the epidemiology of measles in Tianjin, China.

China has repeatedly used supplemental immunization activities (SIAs) to work towards measles elimination, but it is unknown if the SIAs are reaching non-locals - migrants from rural to urban areas. This study characterized temporal trends in measles incidence by local and non-local residency and evaluated the impact of SIAs on measles incidence in Tianjin, China. Daily measles case-counts were tabulated separately by residency. These two datasets were combined so that each day had two observations. Poisson regression was conducted using generalized estimating equations with an exchangeable working correlation structure to estimate rate ratios (RRs). There were 12465 measles cases in Tianjin over the 10-year period. The rate of measles was higher in non-locals than locals before the 2008 SIA (RR 3.60, 95% confidence interval (CI) 3.27-3.96), but this attenuated to a RR of 1.22 between the 2008 and 2010 SIAs (95% CI 1.02-1.45). Following the 2010 SIA, non-locals had a lower rate of measles (RR 0.78, 95% CI 0.69-0.87). The disparity in measles incidence between locals and non-locals was reduced following two SIAs. Sustained public health interventions will be needed to maintain low measles incidence among non-locals given the ongoing migration of people throughout China.

Resurgence of measles in Serbia 2010-2011 highlights the need for supplementary immunization activities.

Between December 2010 and August 2011 an outbreak of measles occurred in Serbia with 363 reported cases. Sera and/or nose/throat swabs were collected from 193 patients and tested for measles-specific IgM antibodies by ELISA and viral RNA by RT-PCR, respectively. Epidemiological data were obtained from the surveillance database of the Institute of Public Health of Serbia. Of the 363 cases involved in the outbreak, 113 were laboratory confirmed. More than one third of the patients were hospitalized (n = 130, 35·8%) and for 15 (4·1% of the reported outbreak cases) the infection was complicated by pneumonia. Mostly pre-school children aged ⩽4 years (37·8%) and adults aged ⩾30 years (27·3%) were affected. The majority of patients belonged to the Roma population with a preponderance of female cases (57·0%). Nearly 94% of the patients were either unvaccinated or of unknown vaccination status. The main outbreak virus was the D4-Hamburg strain. The outbreak in Serbia occurred after several years of very low measles incidence despite a high routine immunization coverage in the general population, suggesting that special efforts to identify and vaccinate susceptible population groups are required even in countries with apparently good disease control.

Vaccine-associated measles in the low-incidence country of Korea over a 10-year period.

As the incidence of measles decreases, cases reported as suspected measles will increasingly involve rash associated with measles vaccination itself. In this study, we assessed vaccine-associated measles cases reported in Korea between 2002 and 2012 using a standardized assessment and following by the World Health Organization case definition criteria. We retrospectively analyzed data regarding (i) wild-type measles and (ii) vaccine-associated measles in patients aged 12-23 months. The presence or absence of fever, rash, cough, coryza, conjunctivitis, and Koplik spots were reviewed. Males were more likely to be reported with vaccine-associated measles than with wild-type measles (68% vs. 47%, P < 0.05). The number of patients with wild-type measles peaked between April and July, whereas that of patients with vaccine-associated measles remained relatively constant throughout the year. However, after excluding the cases reported during the 2007 outbreak in Korea, the trend was similar between the two groups. Cough, coryza, and conjunctivitis were more likely to be present in patients with wild-type measles (32-61% vs. 10-43%, P < 0.05); conversely, the absence of these symptoms was noted in most patients with vaccine-associated measles. We therefore conclude that cough, coryza, and conjunctivitis may be useful as key positive findings to distinguish between wild-type measles and vaccine-associated measles infection among 12-23-month-old patients in a country with a low incidence of measles.

Characteristics of 5-year-olds who catch up with the combined measles, mumps, and rubella vaccine: findings from a contemporary UK cohort

BackgroundThe national measles, mumps, and rubella (MMR) catch-up programme, launched in April, 2013, aims to increase vaccine uptake in groups with low immunisation rates. Cover of Vaccination Evaluated Rapidly (COVER) provides routine data for monitoring of national and local immunisation coverage; however, records are not held at the individual level and cannot be used to examine vaccine catch up or individual-level characteristics associated with uptake. We examined predictors of catch up with MMR in a contemporary cohort of children targeted by the catch-up programme. MethodsWe used data from the most recent UK cohort, the Millennium Cohort Study (MCS). Families of children born in the UK in 2000–02 were contacted via opt-out letters; data were collected from 18 818 children, of whom 18 296 were singletons. At ages 3 and 5 years, participants were followed up by letter, telephone (when possible), and a visit. 12 989 (71%) singleton children from the initial cohort responded to all three sweeps. We analysed data for 751 (6%) children who were unimmunised with the MMR at age 3 years. We estimated unadjusted risk ratios (RRs) and 95% CIs for partial (received one MMR) and full (two MMRs) catch up by age 5 years (baseline: remaining unimmunised) according to various social, economic, and demographic characteristics and reasons reported by parents for not immunising their child at age 3 years. Significantly associated variables in univariable analyses (p<0·10) were entered into multivariable models for partial and full catch up, by a forward stepwise technique. Findings440 of 751 children (60·3%, 95% CI 56·2–64·3) remained unvaccinated; 127 (16·1%, 13·3–19·3) partially and 184 (23·6%, 20·1–27·5) fully caught up. In multivariable models, children from families who did not speak English at home were nearly five times more likely to partially catch up than were children living in homes where only English was spoken (RR 4·68, 95% CI 3·63–6·03); full catch up was also more likely in this group (1·90, 1·08–3·32). Children were more likely to fully catch up if they were from Pakistani or Bangladeshi (2·40, 1·38–4·18) or other ethnic origins (1·88, 1·08–3·29) compared with if they were white British; living in socially rented accommodation compared with owner occupiers (1·86, 1·34–2·56); and living outside compared with inside London (1·95, 1·32–2·89). Full catch up was less likely if parents reported medical reasons (RR 0·43, 95% CI 0·25–0·74) or a conscious decision (0·33, 0·23–0·48) for not immunising at age 3 years (compared with practical reasons). InterpretationParents of children who partially or fully caught up with MMR experienced practical barriers to receiving immunisation (such as missing an appointment) and were from ethnic minority or disadvantaged groups. Time to uptake could be minimised in these families by reducing practical barriers—eg, by providing information in community languages and offering vaccination in alternative settings. Families who continued to reject MMR were from more advantaged backgrounds and made a conscious decision to not immunise early on. Families should be given opportunities to discuss concerns with health professionals, who in turn should be trained for effective communication about immunisation. Our findings refer to a period with high parental concerns around the safety of the vaccine and low incidence of measles. Predictors of catch up in families with young children might differ during times of measles outbreaks. Still, professionals striving to increase MMR uptake should consider these findings in light of the characteristics of their local populations. FundingThe Centre for Paediatric Epidemiology and Biostatistics is supported in part by the MRC in its capacity as the MRC Centre of Epidemiology for Child Health. Research at the UCL Institute of Child Health and Great Ormond Street Hospital for Children receives a proportion of the funding from the Department of Health's NIHR Biomedical Research Centres funding scheme. AP is funded by a MRC fellowship.

Absence of endemic measles transmission in a highly vaccinated population from 1999 to 2008: Implications of sustained measles elimination in Taiwan

BackgroundMeasles remains a leading vaccine-preventable cause of child mortality worldwide. The impact of vaccination programs can be seen in the increasingly low incidence of measles. However, cases of measles continue to occur in low numbers every year in Taiwan. We assessed the epidemiology of measles in Taiwan from 1999 to 2008 with a focus on domestic versus imported cases. MethodsWe analyzed the data reported to surveillance systems at the Taiwan Center for Disease Control, where viral isolation was performed. ResultsA total of 84 measles cases were reported from 1999 to 2008 in Taiwan with the incidence of measles varying from 0 to 1.5 per 1,000,000 people per year, peaking in 2002 and again in 2008. The incidence decreased with increasing age in both males and females. Among the 84 reported measles cases, 39 (46%) originated internationally, 8 (10%) were epidemiologically linked to imported cases and the source was unknown in 37 (44%) of the cases. The unknown-source cases were analyzed for potential evidence of endemic measles transmission. Most of the measles cases that occurred in Taiwan from 1999 to 2008 were associated with imported cases. No endemic transmission of measles in Taiwan was identified. ConclusionsThis study suggests that maintaining the high rate of vaccination coverage is needed to prevent future outbreak and sustain the elimination of measles in Taiwan.

Further efforts needed to achieve measles elimination in Germany: results of an outbreak investigation.

To determine morbidity and costs related to a large measles outbreak in Germany and to identify ways to improve the country's national measles elimination strategy. We investigated a large outbreak of measles in the federal state of North Rhine-Westphalia (NRW) that occurred in 2006 after 2 years of low measles incidence (< 1 case per 100,000). WHO's clinical case definition was used, and surveillance data from 2006 and 2001 were compared. All cases notified in Duisburg, the most severely affected city, were contacted and interviewed or sent a questionnaire. Health-care provider costs were calculated using information on complications, hospitalization and physician consultations. In NRW, 1749 cases were notified over a 48-week period. Compared with 2001, the distribution of cases shifted to older age groups (especially the 10-14 year group). Most cases (n = 614) occurred in Duisburg. Of these, 81% were interviewed; 15% were hospitalized and two died. Of the 464 for whom information was available, 80% were reported as unvaccinated. Common reasons for non-vaccination were parents either forgetting (36%) or rejecting (28%) vaccination. The average cost per measles case was estimated at 373 euros. An accumulation of non-immune individuals led to this outbreak. The shift in age distribution has implications for the effectiveness of measles control and the elimination strategy in place. Immediate nationwide school-based catch-up vaccination campaigns targeting older age groups are needed to close critical immunity gaps. Otherwise, the elimination of measles in Germany and thus in Europe by 2010 will not be feasible.

Dynamics and control of measles in Portugal: Accessing the impact of anticipating the age for the first dose of MMR from 15 to 12 months of age

The all-time low incidence of measles in Portugal in the recent years, raises questions regarding whether the disease has been eliminated, the role of recent control measures, and the epidemiological consequences of the rise in the proportion of newborns to vaccinated mothers, as opposed to those born to mothers who acquired immunity by natural infection. We estimate the vaccination coverage against measles in Portugal on a cohort-by-cohort basis, and incorporate this information into an age-structured seasonally-driven mathematical model aimed at reproducing measles dynamics in the past decades. The model reproduces documented trends in disease notifications and the serological profile of the Portuguese population, as estimated by a recent National Serological Survey. We provide evidence that the effective reproduction number (R(e)) of measles has been driven below 1 in Portugal, and that sustained measles elimination is crucially dependent upon the maintenance of a high (>95%) coverage with the MMR I vaccine in the future. If the vaccination coverage decreases to levels around 90% the anticipation of the first dose of the MMR I from 15 to 12 months of age, will ensure that R(e) remains below 1.

Parental Vaccine Beliefs and Child's School Type

Journal of School HealthVolume 75, Issue 7 p. 276-280 Free Access Parental Vaccine Beliefs and Child's School Type Allison M. Kennedy, Allison M. KennedySearch for more papers by this authorDeborah A. Gust, Deborah A. GustSearch for more papers by this author Allison M. Kennedy, Allison M. KennedySearch for more papers by this authorDeborah A. Gust, Deborah A. GustSearch for more papers by this author First published: 11 August 2005 https://doi.org/10.1111/j.1746-1561.2005.00037.xCitations: 28 Allison M. Kennedy, MPH, Epidemiologist, (ark2@cdc.gov); and 2Deborah A. Gust, PhD, MPH, Health Scientist, (dgg6@cdc.gov), Centers for Disease Control and Prevention, 1600 Clifton Road, NE, Mailstop E-61, Atlanta, GA 30333. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat References 1 Hall S, Galil K, Watson B, Seward J. The use of school-based vaccination clinics to control varicella outbreaks in two schools. Pediatrics. 2000; 105(1): e17. 2 Murphy TV, Pastor P, Turner SB, et al. Estimating immunization coverage from school-based childhood immunization records. Pediatr Infect Dis J. 1995; 14(7): 561– 567. 3 Robbins KB, Brandling-Bennett AD, Hinman AR. Low measles incidence: association with enforcement of school immunization laws. Am J Public Health. 1981; 71(3): 270– 274. 4 Gerald DE, Hussar WJ. Projections of Education Statistics to 2012 (NCES 2002–030). Washington, DC: US Department of Education, National Center for Education Statistics; 2002. 5 Linton LS, Peddecord KM, Seidman RL, et al. Implementing a seventh grade vaccination law: school factors associated with completion of required immunizations. Prev Med. 2003; 36: 510– 517. 6 Fredrickson DD, Kies KM, Burbach CA. Immunization compliance among public and private school children. J Sch Health. 1997; 67(2): 75– 77. 7 Pollard W. Use of consumer panel survey data for public health communication planning: an evaluation of survey results. Proceedings of the Annual Meeting of the American Statistical Association, August 11–15, 2002; New York, NY. 8 Glanz K, Basil M, Maibach E, Goldberg J, Snyder D. Why Americans eat what they do: taste, nutrition, cost, convenience, and weight control concerns as influences on food consumption. J Am Diet Assoc. 1998; 98(10): 1118– 1126. 9 Centers for Disease Control and Prevention. Knowledge about cases of peptic ulcer disease—United States, March-April 1997. MMWR Morb Mortal Wkly Rep. 1997; 46(42): 985– 987. 10 Weir MR, Maibach EW, Bakris GL, et al. Implications of a health lifestyle and medication analysis for improving hypertension control. Arch Intern Med. 2000; 160: 481– 490. 11 Slater MD, Basil MD, Maibach EW. A cluster analysis of alcohol-related attitudes and behaviors in the general population. J Stud Alcohol. 1999; 60: 667– 674. 12 Wang SS, Fridinger F, Sheedy KM, Khoury MJ. Public attitudes regarding the donation and storage of blood specimens for genetic research. Community Genet. 2001; 4: 18– 26. 13 Maibach EW, Maxfield A, Ladin K, Slater M. Translating health psychology into effective health communication: The American Healthstyles audience segmentation project. J Health Psychol. 1996; 1(3): 261– 277. 14 Bielick S, Chandler K, Broughman SP. Homeschooling in the United States: 1999 (NCES 2001-033). Washington, DC: US Department of Education, National Center for Education Statistics; 2001. 15 Stevens M. Kingdom of Children: Culture and Controversy in the Homeschooling Movement. Princeton, NJ: Princeton University Press; 2001. 16 Houston RG, Toma EF. Home schooling: an alternative school choice. South Econ J. 2003; 69(4): 920– 935. 17 Rota JS, Salmon DA, Rodewald LE, Chen RT, Hibbs BF, Gangarosa EJ. Processes for obtaining nonmedical exemptions to state immunization laws. Am J Public Health. 2001; 91(4): 645– 648. 18 Gellin BG, Maibach EW, Marcuse EK. Do parents understand immunizations? A national telephone survey. Pediatrics. 2000; 106(5): 1097– 1102. Citing Literature Volume75, Issue7September 2005Pages 276-280 ReferencesRelatedInformation

The interruption of transmission of indigenous measles in the United States during 1993.

The United States has a goal to eliminate all indigenous cases of measles by the year 2000. Initial interruption of indigenous measles transmission would be expected during a period of very low measles incidence as occurred during late 1993. Indigenous measles cases (i.e. cases acquired in the United States and not traceable to any imported case) from 1993 were investigated to determine their source of infection. The probability of sustained undetected measles transmission between isolated indigenous cases was estimated. Of the 312 measles cases reported for 1993, only 25 (8%) occurred after September 19. Of these only 4 cases (16%) could be classified as indigenous. The estimated probability that any of these 4 cases resulted from indigenous measles transmission in theirs or any adjoining counties was 0.05 or less. Interruption of indigenous measles transmission appears to have occurred for the first time throughout the United States in 1993. This event provides strong support for the current national strategy for measles elimination. However, complete elimination of indigenous measles will require maintaining high population immunity to prevent spread from imported cases and attaining global measles control to prevent the importation of measles.

Measles vaccines: a review of adverse events.

A great deal of controversy has recently been generated over the publication of several articles implicating measles vaccine in the induction of Crohn's disease and autism. The publication of this work has already had a negative impact on measles vaccine acceptance in the UK. These allegations are particularly troubling because they arise in the context of increased use of measles vaccine as global control of measles nears and the international community considers strategies for a drive towards eradication. In 1994, the US Institute of Medicine reviewed the world literature and published a comprehensive review of adverse events associated with measles-containing vaccines. Reviewing the literature published between 1994 and the present day, reveals that there is considerable new data suggesting that modified gelatin rather than egg proteins is responsible for most episodes of anaphylaxis following measles vaccination. New work weakens the possible links between measles vaccine and subacute sclerosing panencephalitis and Guillain-Barré syndrome, but strengthens the rare association of measles-containing vaccines with post infectious encephalomyelitis. The alleged associations between measles vaccination and Crohn's disease and autism are based upon weak science and have largely been refuted by a large volume of stronger work. A review of the data generated in the last 4 years amply demonstrates the continued efforts of the scientific community to monitor and understand true measles vaccine-associated adverse events. The rapidity and clarity of this same community's debunking of the spurious associations with Crohn's disease and autism suggests that those charged with vaccination programmes have learned from past mistakes. During 30 years of worldwide use, measles vaccination has proven to be one of the safest and most successful health interventions in the history of mankind. It is not a 'perfect' vaccine, but the benefits of measles vaccination far outweigh the risks even in countries with low incidence of measles and high rates of measles vaccine coverage.

A 'post-honeymoon period' measles outbreak in Muyinga sector, Burundi.

In Muyinga sector, Burundi, an area with good vaccination levels against measles and recent low incidence of measles, a major outbreak of measles in 1988 raised questions about the efficacy of the immunization programme. To help answer these questions, we 1) reviewed programme data on doses of measles vaccine administered, vaccine coverage, and measles incidence, and 2) conducted a census of the affected area to examine vaccine efficacy and measles mortality. We found that between 1980 and 1988 in Burundi, 1) measles vaccine coverage by age 1 had increased from 0% to 55%, 2) the incidence of reported measles cases declined from 12.1/1000 to 6.2/1000, 3) reported measles mortality dropped from 0.18/1000 to 0.08/1000, and 4) the interepidemic period had increased from 25 to 35 months. In the census, the best estimate of measles vaccine efficacy administered at 9 months of age was 73%. Measles increased the risk of death by 2.5-fold with the effect limited to the first month after measles. This outbreak demonstrated the 'post-honeymoon period' epidemic predicted by mathematical models in which outbreaks occur among accumulated susceptibles in a partially immunized population. Understanding this phenomenon is important in providing a basis for improved strategies of measles control. Such outbreaks present new challenges to newly maturing immunization programmes in improving skills in surveillance, outbreak investigation, and public relations.

Protective efficacy of high-titre measles vaccines administered from the age of five months: a community study in rural Senegal

Using data on incidence and secondary attack rates, we examined the protective efficacy of high-titre Edmonston-Zagreb (EZ) and Schwarz (SW-HT) measles vaccines administered at 5 months. Control children were assigned to placebo at age 5 months and standard Schwarz (SW-std) measles vaccine at 9–10 months of age. A large proportion of measles cases was verified serologically. Though high-titre vaccines seemed to be protective before 10 months of age, a significant reduction in disease could not be demonstrated due to low incidence of measles. After 10 months of age, SW-std given at 10 months gave a vaccine efficacy of 100% and induced better protection than SW-HT ( P = 0·030) and EZ-HT ( P = 0·128) administered at 5 months. In studies of secondary attack rates in the compound, vaccine efficacy was 91% (75%–97%) for EZ-HT, 85% (40%–96%) for SW-HT, and 100% for SW-std. Attack rates were correlated with intensity of exposure ( P = 0·0006), being much higher for children exposed in the same hut than for those living in the same compound but in a different household (relative risk = 3·36 [1·32–8·57]). The attack rate was significantly lower among vaccinated than unvaccinated children with no detectable measles antibody (relative risk = 0·41 [0·18–0·93]). In rural areas with a high coverage in the surrounding community, a single dose at 9–10 months may provide sufficient protection. Since high-titre vaccines have been associated with higher mortality than SW-std, further improvements in measles control before 9 months may require two-dose strategies with standard vaccines.

Changing epidemiology of measles in Hong Kong from 1961 to 1990--impact of a measles vaccination program.

With the use of measles vaccine since 1967, Hong Kong has experienced a low incidence of measles until a major outbreak in 1988. A shift in the distribution of susceptible children to older age groups was suddenly accelerated in the 1988 outbreak. The attack rate increased by 18.9-fold for children greater than 10 years old, while that for those in the best-protected age group of 1-4 years was only 2.2-fold. Of the cases during that outbreak, 56.3% would have been considered preventable with the present vaccination regimen, and vaccine failures accounted for only 20.4% of the cases. Present control strategies aim at increasing the coverage rate rather than introducing a two-dose regimen, which may be necessary when vaccine failures account for a larger proportion of measles cases.

Immunization of Asymptomatic HIV-infected Children with Measles Vaccine: Assessment of Risks and Benefits

Because HIV infection is associated with immunologic abnormalities, concerns have been expressed about the safety and efficacy of vaccination of infected children with live virus vaccines. The authors used decision analysis to assess the likely impacts of four alternative policies for immunization of asymptomatic HIV-infected children with measles vaccine. Probabilities for vaccine efficacy, vaccine-related adverse events, and measles complications in HIV-infected children and the prevalence of HIV infection in the birth cohort were obtained from a modified Delphi survey. Using median estimates from the Delphi survey, there were no major differences in outcomes under any proposed policy. Using the most extreme estimates, serologic testing and exclusion of seropositive children from vaccination or exclusion of all high-risk children decreased vaccine-associated adverse events without greatly increasing measles complications, primarily because of the current low incidence of measles. Under conditions assumed to exist in the United States today, alternate immunization policies have only minor differences in societal impact although costs would certainly differ.

Swedish experience of two dose vaccination programme aiming at eliminating measles, mumps, and rubella.

In 1982 a two dose regimen was introduced in Sweden for the combined vaccination against measles, mumps, and rubella of children aged 18 months and 12 years. Since 1977 about half of the preschool children were vaccinated against measles annually, and since 1974 about 80% of 12 year old girls were vaccinated against rubella. During the period 1982 to 1985 90-93% of the eligible age cohorts of 18 month old children and 88-91% of the 12 year old children were immunised with the new combined vaccine. A study in 1982 of about 140 18 month old children who were nearly all seronegative before vaccination showed that 96%, 92%, and 99% seroconverted against measles, mumps, and rubella, respectively. A second study was carried out in 1983 of 247 12 year old children, of whom 11% lacked antibodies to measles, 27% to mumps, and 45% to rubella. This showed seroconversion in 82% and 80% against measles and mumps, respectively, and all children seroconverted against rubella. In the latest study in 1985 of 496 12 year olds 9% and 13% were seronegative against measles and mumps before vaccination, and 41% against rubella. Of these, 88% seroconverted to measles and 80% to mumps, and all converted to rubella when sera were tested by the haemolysis in gel method. After a neutralisation test against measles as well all children showed immunity to the disease. A low incidence of measles and declining figures for mumps and rubella were reported in 1984 to 1986. An outbreak of rubella during 1985 affected mainly boys in age cohorts in which only the girls had been vaccinated during the 1970s.