The future of measles in highly immunized populations. A modeling approach

Global trends in measles publications

INTRODUCTION

Beginning with the 1960s, this review analyzes trends in publications on measles indexed by the National Library of Medicine from January 1960 to mid-2018. It notes both the growth in numbers of published papers, and the increasing number and proportion of publications, in the current century, of articles on such items as costing, measles elimination, and determinants of coverage.

METHODS

A two-person team extracted from the National Library of Medicine (NLM) homepage all citations on measles beginning in 1960 and continuing through mid-2018. These were then classified both by overall number and by subject matter, with tabular summaries of both by decade and by subject matter. The tabular presentation forms the basis for a discussion of the ten most frequently cited subjects, and publication trends, with a special emphasis on the current century.

RESULTS

As in the past, the most often currently published items have been on coverage and its determinants, measles elimination, outbreak reports, SSPE, and SIAs. The putative relationship between vaccination and autism saw a spurt of articles in the 1990s, rapidly declining after the IOM report rejecting the causative hypothesis.

CONCLUSION

There is a discussion on the sequencing of polio and measles eradication, the former unlikely before 2022, and an examination of likely research priorities as the world moves from measles control to measles eradication. There is a key role for social science in combatting vaccination reticence. The role of technical innovations, such as micropatch vaccination, is discussed.

Seroimmunity to measles and mumps among medical students and nurses in a teaching hospital in Lebanon

Two hundred thirty-three newly enrolled medical and nursing students at the American University of Beirut, Lebanon, were tested for antibodies to measles and mumps. Antibodies to measles were detected in 95% of the sample, and antibodies to mumps in 84% of the sample. Susceptible individuals were appropriately immunized.

The measles outbreak in Chikuhou District, Fukuoka, Japan, 1990: correlation between herd immunity level and outbreak size

A measles outbreak occurred in the Chikuhou district of Fukuoka, Japan from May to October 1990, during which 71 patients were cared for at the Itoda Public Hospital. Hospital records revealed a large outbreak in the adjacent town of Kanada. In order to characterize the outbreak, questionnaires were sent to all preschool-age children in Itoda (73% effective response) and in Kanada (76% effective response) requesting information about their vaccination and/or history of measles. The number of patients was 22 (4%) in Itoda and 63 (14%) in Kanada, most of these being preschoolers, while the vaccination rate was 61% and 44%, respectively. The herd immunity levels in age-specific groups were compared between the two towns. Before the epidemic, the immunity level of 1 year old children in Kanada, who showed the higher attack rate, was lower (18%) than that in Itoda (39%), while after the epidemic it rose above 60% in both towns. When we studied the correlation between the attack rate and the vaccination rate, or the number of children susceptible to measles (susceptibility rate) in each preschool, the attack rate correlated negatively with the vaccination rate (correlation coefficient [CC] = -0.818; P less than 0.01), and positively with the susceptibility rate (CC 0.860; P less than 0.01). The regressed equation on the correlation indicated that the immunity level should be more than 70% to keep the attack rate under 5% in preschools. After the epidemic, the immunity levels of all preschoolers reached above 70%.(ABSTRACT TRUNCATED AT 250 WORDS)

Serological response to measles revaccination in a highly immunized military dependent adolescent population

In the spring of 1986, there was a measles outbreak in the city of El Paso, Texas, with 92 cases reported to the City-County Health Department. Of those 92 cases, 31 (32%) occurred within a public high school's student population of 2524. A mass measles vaccination program was undertaken at that high school in order to limit the outbreak. The student enrollment included a military dependent population of 368 students. Despite documented histories of prior measles immunizations in this military dependent subgroup, three individuals contracted the disease. Since this subgroup of students represented a highly immunized adolescent population, it was of interest to serologically determine their immune status prior to and following reimmunization with the expectation that such a study would provide information relating to the level of "protective" immunity. Prevaccination and postvaccination sera were obtained from 95 students. Results of measuring anti-measles antibody activity by ELISA indicate that 13 (14%) students responded to revaccination and experienced a fourfold or greater rise in IgG antibody levels. There were no detectable IgM responses. All of the students who responded to revaccination produced an anamnestic response (IgG boost only). Since most of these individuals had received first immunizations at 15 months of age or older, these findings suggest that secondary vaccine failure (waning immunity) was responsible for the putative "lowered" immunity in these individuals, instead of primary vaccine failure (maternal antibody suppression). These findings support current recommendations for measles booster revaccination of school-age children and adolescents.

Prevalence of antibodies against measles virus in Tripoli, The Socialist People's Libyan Arab Jamahiriya

A compulsory immunization policy against measles was introduced in the Socialist People's Libyan Arab Jamahiriya in 1972. Data are presented to show that a decreased incidence of measles followed this programme. Nevertheless, measles epidemics still occur and the serological status of the population has, therefore, been examined. In the area of Tripoli, measles haemagglutination-inhibiting (HI) antibodies were found at a titre of greater than or equal to 1:10 in 97% of the adult population, and in 78%, 100% and 97.1% of schoolchildren of primary, preparatory and secondary schools respectively. The relatively high HI titres observed, particularly in adults, imply that antigenic restimulation of antibody against measles occurs and thus that coverage by immunization remains inadequate. Increased efforts to improve immunization coverage at an early age are recommended.

The role of secondary vaccine failures in measles outbreaks

An outbreak of measles in 1985-86 in a community where measles vaccine trials had been carried out from 1974-76 allowed the assessment of the role of secondary vaccine failures in previously immunized children. A total of 188 children from the vaccine trial were followed. Of these, 175 seroconverted initially while 13 (6 per cent) required re-immunization (primary failure). A total of 13 cases of measles, eight of which were laboratory and/or physician-confirmed, were reported in this cohort. Of these, nine cases occurred in the 175 subjects who had hemagglutination inhibition test (HI) and neutralizing antibody responses following the initial immunization. These nine cases represent secondary vaccine failures. An additional four cases occurred in the 13 subjects with primary vaccine failure. We conclude that secondary vaccine failures occur and that while primary failures account for most cases, secondary vaccine failures contribute to the occurrence of measles cases in an epidemic. A booster dose of measles vaccine may be necessary to reduce susceptibility to a sufficiently low level to allow the goal of measles elimination to be achieved.