Measles Outbreak Associated With Low Vaccine Effectiveness Among Adults in Pohnpei State, Federated States of Micronesia, 2014

Onward transmission of measles virus among vaccinated cases in a large community outbreak in Auckland, New Zealand, 2019

BACKGROUND

Isolation of cases and quarantining of non-immune contacts are the mainstay of measles outbreak management in elimination settings. Serology testing of exposed contacts may not be feasible in large outbreaks; therefore, vaccination history is used as a proxy for determining immunity to measles and thus prevention of onward virus transmission. This study sought to investigate the risk of measles virus transmission from individuals with a history of one or two doses of measles-containing vaccine (MCV).

METHODS

 Retrospective analysis of data from measles cases reported to Auckland Regional Public Health Service during the 2019 Auckland region measles outbreak. Vaccination history was verified using patient records and the New Zealand National Immunisation Register. Onward transmission was determined through case interviews and assessment of exposed contacts.

RESULTS

 1451 measles cases were assessed as eligible for vaccination at the time of measles outbreak. Of these, 1015 (70.0%) were unvaccinated, 220 (15.2%) had unknown vaccination status, 139 (9.6%) had received only one dose of MCV and 77 (5.3%) had received two doses of the vaccine. Compared to unvaccinated cases, the odds of onward transmission were lower among those with one dose only (OR 0.41, 95% CI: 0.20-0.75) or two doses of MCV (OR 0.44, 95% CI: 0.17-0.95). Median time since vaccination was longer among those with onward transmission compared to those without onward transmission for one and two doses of the vaccine, suggesting a potential effect of waning immunity among this cohort.

CONCLUSION

 These findings support the hypothesis that measles cases with a history of prior vaccination are less likely to transmit the virus to others compared to unvaccinated cases. Such information can be used to support decisions around quarantine requirements for vaccinated contacts in future measles outbreaks.

Breakthrough Measles among Vaccinated Adults Born during the Post-Soviet Transition Period in Mongolia

Mongolia experienced a nationwide measles outbreak during 1 March 2015-31 December 2016, with 49,077 cases reported to the WHO; many were among vaccinated young adults, suggesting a possible role of vaccine failure. Advanced laboratory methods, coupled with detailed epidemiological investigations, can help classify cases as vaccine failure, failure to vaccinate, or both. In this report, we conducted a study of cases to identify risk factors for breakthrough infection for a subset of laboratory-confirmed measles cases. Of the 193 cases analyzed, only 19 (9.8%) reported measles vaccination history, and 170 (88%) were uncertain. Measles-specific IgG avidity testing classified 120 (62%) cases as low IgG avidity, indicating no prior exposure to measles. Ten of these cases with low IgG avidity had a history of measles vaccination, indicating primary vaccine failure. Overall, sixty cases (31%) had high IgG avidity, indicating breakthrough infection after prior exposure to measles antigen through vaccination or natural infection, but the IgG avidity results were highly age-dependent. This study found that among young children aged 9 months-5 years, breakthrough infection was rare (4/82, 5%); however, among young adults aged 15-25 years, breakthrough infection due to secondary vaccine failure (SVF) occurred on a large scale during this outbreak, accounting for the majority of cases (42/69 cases, 61%). The study found that large-scale secondary vaccine failure occurred in Mongolia, which highlights the potential for sustained outbreaks in post-elimination settings due to "hidden" cohorts of young adults who may have experienced waning immunity. This phenomenon may have implications for the sustainability of measles elimination in countries that remain vulnerable to the importation of the virus from areas where it is still endemic. Until global measles elimination is achieved, enhanced surveillance and preparedness for future outbreaks in post- or peri-elimination countries may be required.

Multiplex Bead Assay for the Serological Surveillance of Measles and Rubella

There is increasing interest in evaluating antibody responses to multiple antigen targets in a single assay. Immunity to measles and rubella are often evaluated together because immunity is provided through combined vaccines and because routine immunization efforts and surveillance for measles and rubella pathogens are combined in many countries. The multiplex bead assay (MBA) also known as the multiplex immunoassay (MIA) described here combines the measurement of measles- and rubella-specific IgG antibodies in serum quantitatively according to international serum standards and has been successfully utilized in integrated serological surveillance.

Measles Virus Neutralizing Antibody Response and Durability Two Years after One or Two Doses of Measles-Mumps-Rubella Vaccine among Young Seronegative Healthcare Workers

Although there have been several studies regarding the immunogenicity of one or two booster doses of the measles−mumps−rubella (MMR) vaccine in measles-seronegative young adults, limited data are available about how long the immune response is sustained compared with natural infection. This study included seronegative healthcare workers (HCWs) (aged 21−38 years) who received one or two doses of the measles−mumps−rubella (MMR) vaccine and HCWs with laboratory-confirmed measles infection during an outbreak in 2019. We compared neutralizing antibody titers measured using the plaque reduction neutralization (PRN) test and measles-specific immunoglobulin G (IgG) using chemiluminescent immunoassays 2 years after vaccination or infection. Among 107 HCWs with seronegative measles IgGs, the overall seroconversion rate of measles IgGs remained 82.2% (88/107), and 45.8% (49/107) of the participants had a medium (121−900) or high (>900) PRN titer after 2 years from one or two booster doses. The measles-neutralizing antibody titers of both PRN titer (ND50) and geometric mean concentration 2 years after natural infection were significantly higher than those of one or two booster doses of the MMR vaccine (p < 0.001 and p < 0.001, respectively). Our results suggest that serologic screening followed by appropriate postexposure prophylaxis can be beneficial for young HCWs without a history of natural infection especially in a measles outbreak setting, because of possible susceptibility to measles despite booster MMR vaccination 2 years ago. Long-term data about sustainable humoral immunity after one or two booster vaccination are needed based on the exact vaccination history.

Prevalence of measles antibodies among migrant workers in Singapore: a serological study to identify susceptible population subgroups

Background

In 2019, two clusters of measles cases were reported in migrant worker dormitories in Singapore. We conducted a seroprevalence study to measure the level of susceptibility to measles among migrant workers in Singapore.

Methods

Our study involved residual sera of migrant workers from seven Asian countries (Bangladesh, China, India, Indonesia, Malaysia, Myanmar and the Philippines) who had participated in a survey between 2016 and 2019. Immunoglobulin G (IgG) antibody levels were first measured using a commercial enzyme-linked immunosorbent assay (ELISA) test kit. Those with equivocal or negative IgG results were further evaluated using plaque reduction neutralization test (PRNT).

Results

A total of 2234 migrant workers aged 20–49 years were included in the study. The overall prevalence of measles IgG antibodies among migrant workers from the seven Asian countries was 90.5% (95% confidence interval 89.2–91.6%). The country-specific seroprevalence ranged from 80.3 to 94.0%. The seroprevalence was significantly higher among migrant workers born in 1965–1989 than those born in 1990–1999 (95.3% vs. 86.6%, p < 0.0005), whereas there was no significant difference by gender (90.8% in men vs. 89.9% in women, p = 0.508). 195 out of 213 samples with equivocal or negative ELISA results were tested positive using PRNT.

Conclusion

The IgG seroprevalence in migrant workers was below the herd immunity threshold of 95% for measles. Sporadic outbreaks may occur in susceptible individuals due to high transmissibility of measles virus. Seroprevalence surveys can help identify susceptible subgroups for vaccination.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07066-2.

Vaccines for measles, mumps, rubella, and varicella in children

BACKGROUND

Measles, mumps, rubella, and varicella (chickenpox) are serious diseases that can lead to serious complications, disability, and death. However, public debate over the safety of the trivalent MMR vaccine and the resultant drop in vaccination coverage in several countries persists, despite its almost universal use and accepted effectiveness. This is an update of a review published in 2005 and updated in 2012.

OBJECTIVES

To assess the effectiveness, safety, and long- and short-term adverse effects associated with the trivalent vaccine, containing measles, rubella, mumps strains (MMR), or concurrent administration of MMR vaccine and varicella vaccine (MMR+V), or tetravalent vaccine containing measles, rubella, mumps, and varicella strains (MMRV), given to children aged up to 15 years.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library 2019, Issue 5), which includes the Cochrane Acute Respiratory Infections Group's Specialised Register, MEDLINE (1966 to 2 May 2019), Embase (1974 to 2 May 2019), the WHO International Clinical Trials Registry Platform (2 May 2019), and ClinicalTrials.gov (2 May 2019).

SELECTION CRITERIA

We included randomised controlled trials (RCTs), controlled clinical trials (CCTs), prospective and retrospective cohort studies (PCS/RCS), case-control studies (CCS), interrupted time-series (ITS) studies, case cross-over (CCO) studies, case-only ecological method (COEM) studies, self-controlled case series (SCCS) studies, person-time cohort (PTC) studies, and case-coverage design/screening methods (CCD/SM) studies, assessing any combined MMR or MMRV / MMR+V vaccine given in any dose, preparation or time schedule compared with no intervention or placebo, on healthy children up to 15 years of age.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the methodological quality of the included studies. We grouped studies for quantitative analysis according to study design, vaccine type (MMR, MMRV, MMR+V), virus strain, and study settings. Outcomes of interest were cases of measles, mumps, rubella, and varicella, and harms. Certainty of evidence of was rated using GRADE.

MAIN RESULTS

We included 138 studies (23,480,668 participants). Fifty-one studies (10,248,159 children) assessed vaccine effectiveness and 87 studies (13,232,509 children) assessed the association between vaccines and a variety of harms. We included 74 new studies to this 2019 version of the review. Effectiveness Vaccine effectiveness in preventing measles was 95% after one dose (relative risk (RR) 0.05, 95% CI 0.02 to 0.13; 7 cohort studies; 12,039 children; moderate certainty evidence) and 96% after two doses (RR 0.04, 95% CI 0.01 to 0.28; 5 cohort studies; 21,604 children; moderate certainty evidence). The effectiveness in preventing cases among household contacts or preventing transmission to others the children were in contact with after one dose was 81% (RR 0.19, 95% CI 0.04 to 0.89; 3 cohort studies; 151 children; low certainty evidence), after two doses 85% (RR 0.15, 95% CI 0.03 to 0.75; 3 cohort studies; 378 children; low certainty evidence), and after three doses was 96% (RR 0.04, 95% CI 0.01 to 0.23; 2 cohort studies; 151 children; low certainty evidence). The effectiveness (at least one dose) in preventing measles after exposure (post-exposure prophylaxis) was 74% (RR 0.26, 95% CI 0.14 to 0.50; 2 cohort studies; 283 children; low certainty evidence). The effectiveness of Jeryl Lynn containing MMR vaccine in preventing mumps was 72% after one dose (RR 0.24, 95% CI 0.08 to 0.76; 6 cohort studies; 9915 children; moderate certainty evidence), 86% after two doses (RR 0.12, 95% CI 0.04 to 0.35; 5 cohort studies; 7792 children; moderate certainty evidence). Effectiveness in preventing cases among household contacts was 74% (RR 0.26, 95% CI 0.13 to 0.49; 3 cohort studies; 1036 children; moderate certainty evidence).  Vaccine effectiveness against rubella, using a vaccine with the BRD2 strain which is only used in China, is 89% (RR 0.11, 95% CI 0.03 to 0.42; 1 cohort study; 1621 children; moderate certainty evidence).  Vaccine effectiveness against varicella (any severity) after two doses in children aged 11 to 22 months is 95% in a 10 years follow-up (rate ratio (rr) 0.05, 95% CI 0.03 to 0.08; 1 RCT; 2279 children; high certainty evidence). Safety There is evidence supporting an association between aseptic meningitis and MMR vaccines containing Urabe and Leningrad-Zagreb mumps strains, but no evidence supporting this association for MMR vaccines containing Jeryl Lynn mumps strains (rr 1.30, 95% CI 0.66 to 2.56; low certainty evidence). The analyses provide evidence supporting an association between MMR/MMR+V/MMRV vaccines (Jeryl Lynn strain) and febrile seizures. Febrile seizures normally occur in 2% to 4% of healthy children at least once before the age of 5. The attributable risk febrile seizures vaccine-induced is estimated to be from 1 per 1700 to 1 per 1150 administered doses. The analyses provide evidence supporting an association between MMR vaccination and idiopathic thrombocytopaenic purpura (ITP). However, the risk of ITP after vaccination is smaller than after natural infection with these viruses. Natural infection of ITP occur in 5 cases per 100,000 (1 case per 20,000) per year. The attributable risk is estimated about 1 case of ITP per 40,000 administered MMR doses. There is no evidence of an association between MMR immunisation and encephalitis or encephalopathy (rate ratio 0.90, 95% CI 0.50 to 1.61; 2 observational studies; 1,071,088 children; low certainty evidence), and autistic spectrum disorders (rate ratio 0.93, 95% CI 0.85 to 1.01; 2 observational studies; 1,194,764 children; moderate certainty). There is insufficient evidence to determine the association between MMR immunisation and inflammatory bowel disease (odds ratio 1.42, 95% CI 0.93 to 2.16; 3 observational studies; 409 cases and 1416 controls; moderate certainty evidence). Additionally, there is no evidence supporting an association between MMR immunisation and cognitive delay, type 1 diabetes, asthma, dermatitis/eczema, hay fever, leukaemia, multiple sclerosis, gait disturbance, and bacterial or viral infections.  AUTHORS' CONCLUSIONS: Existing evidence on the safety and effectiveness of MMR/MMRV vaccines support their use for mass immunisation. Campaigns aimed at global eradication should assess epidemiological and socioeconomic situations of the countries as well as the capacity to achieve high vaccination coverage. More evidence is needed to assess whether the protective effect of MMR/MMRV could wane with time since immunisation.

Thermostability of Measles and Rubella Vaccines in a Microneedle Patch

Measles and rubella vaccinations are highly effective at reducing disease prevalence; however, logistic issues related to subcutaneous administration and vaccine wastage limit the extent of vaccination coverage. Microneedle (MN) patches can increase coverage by easing logistics through simplified administration and improved stability. This study demonstrates the thermostability of a bivalent measles and rubella vaccine MN patch. Rubella vaccine stability required pH buffering during drying; potassium phosphate buffer at neutral pH was optimal for both vaccines. Screening 43 excipients for their ability to retain potency during drying and storage yielded sucrose-threonine-potassium phosphate buffer formulation at pH 7.5 as an optimal formulation. MN patches made with this formulation had no significant loss of vaccine titer after one month and remained within a one log10 titer loss cutoff after 3 - 4 months at 5°C, 25°C and 40°C. Finally, these patches were shown to be immunogenic in juvenile rhesus macaques. This work demonstrates the potential for MN patches for measles and rubella vaccination to be removed from the cold chain, which is expected to decrease vaccine cost and wastage, and increase vaccination coverage.

Development of a Measles and Rubella Multiplex Bead Serological Assay for Assessing Population Immunity

Serosurveys are important tools for estimating population immunity and providing immunization activity guidance. The measles and rubella multiplex bead assay (MBA) offers multiple advantages over standard serological assays and was validated by comparison with the enzyme-linked immunosorbent assay (ELISA) and the measles plaque reduction neutralization (PRN) assay. Results from a laboratory-produced purified measles virus whole-virus antigen MBA (MeV WVAL) correlated better with ELISA and PRN than results from the baculovirus-expressed measles nucleoprotein (N) MBA. Therefore, a commercially produced whole-virus antigen (MeV WVAC) was evaluated. Serum IgG antibody concentrations correlated significantly with a strong linear relationship between the MeV WVAC and MeV WVAL MBAs (R = 0.962 and R2 = 0.926). IgG concentrations from the MeV WVAC MBA showed strong correlation with PRN titers (R = 0.846), with a linear relationship comparable to values obtained with the MeV WVAL MBA and PRN assay (R2 = 0.716 and R2 = 0.768, respectively). Receiver operating characteristic (ROC) curve analysis of the MeV WVAC using PRN titer as the comparator resulted in a seroprotection cutoff of 153 mIU/ml, similar to the established correlate of protection of 120 mIU/ml, with a sensitivity of 98% and a specificity of 83%. IgG concentrations correlated strongly between the rubella WVA MBA and ELISA (R = 0.959 and R2 = 0.919). ROC analysis of the rubella MBA using ELISA as the comparator yielded a cutoff of 9.36 IU/ml, similar to the accepted cutoff of 10 IU/ml for seroprotection, with a sensitivity of 99% and a specificity of 100%. These results support use of the MBA for multiantigen serosurveys assessing measles and rubella population immunity.

Measles outbreak investigation process in low- and middle-income countries: a systematic review of the methods and costs of contact tracing

Aim

The occurrence of measles outbreaks has increased, and previously measles-free countries are experiencing a resurgence, making measles elimination by 2020 unlikely. Therefore, outbreak prevention and rapid response strategies will need to be intensified. This systematic review therefore examines whether contact tracing (CT) as compared to no CT is an effective means of reducing measles spread during outbreaks in low- and middle-income countries (LMICs).

Subject and methods

A systematic review was conducted by searching six databases (CINAHL, Global Health, Medline, Cochrane Library, Web of Science and PubMed). The 17 included articles were appraised using the Critical Appraisal Skills Programme checklists and analysed using a narrative synthesis.

Results

CT is often used alongside mass communication strategies and hospital record checks. Interviewing measles cases to identify contacts, and considering everyone who has shared a space with a case as a contact are common CT methods. Also, CT can be done backwards and/or forwards with the measles case as the focal point of the investigation process. The cost per case of an outbreak response dominated by CT is high especially in terms of labour for the health sector and productivity losses for households. However, overall outbreak expenditure can be low if CT results in fewer and less severe measles cases and a short outbreak duration.

Conclusion

CT data as a standalone and comparative active surveillance approach in LMICs is scarce. If CT is initiated early, it can prevent large outbreaks, thereby reducing the economic burden of measles and drive LMICs towards measles elimination.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10389-021-01590-2.

Recent setbacks in measles elimination: the importance of investing in innovations for immunizations

The recent setbacks in efforts to achieve measles elimination goals are alarming. To reverse the current trends, it is imperative that the global health community urgently intensify efforts and make resource commitments to implement evidence-based elimination strategies fully, including supporting research and innovations. The Immunization Agenda 2030: A Global Strategy to Leave No One Behind (IA2030) is the new global guidance document that builds on lessons learned and progress made toward the GVAP goals, includes research and innovation as a core strategic priority, and identifies measles as a “tracer” for improving immunisation services and strengthening primary health care systems. To achieve vaccination coverage and equity targets that leave no one behind, and accelerate progress toward disease eradication and elimination goals, sustained and predictable investments are needed for the identified research and innovations priorities for the new decade.

Vaccines for measles, mumps, rubella, and varicella in children

BACKGROUND

Measles, mumps, rubella, and varicella (chickenpox) are serious diseases that can lead to serious complications, disability, and death. However, public debate over the safety of the trivalent MMR vaccine and the resultant drop in vaccination coverage in several countries persists, despite its almost universal use and accepted effectiveness. This is an update of a review published in 2005 and updated in 2012.

OBJECTIVES

To assess the effectiveness, safety, and long- and short-term adverse effects associated with the trivalent vaccine, containing measles, rubella, mumps strains (MMR), or concurrent administration of MMR vaccine and varicella vaccine (MMR+V), or tetravalent vaccine containing measles, rubella, mumps, and varicella strains (MMRV), given to children aged up to 15 years.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library 2019, Issue 5), which includes the Cochrane Acute Respiratory Infections Group's Specialised Register, MEDLINE (1966 to 2 May 2019), Embase (1974 to 2 May 2019), the WHO International Clinical Trials Registry Platform (2 May 2019), and ClinicalTrials.gov (2 May 2019).

SELECTION CRITERIA

We included randomised controlled trials (RCTs), controlled clinical trials (CCTs), prospective and retrospective cohort studies (PCS/RCS), case-control studies (CCS), interrupted time-series (ITS) studies, case cross-over (CCO) studies, case-only ecological method (COEM) studies, self-controlled case series (SCCS) studies, person-time cohort (PTC) studies, and case-coverage design/screening methods (CCD/SM) studies, assessing any combined MMR or MMRV / MMR+V vaccine given in any dose, preparation or time schedule compared with no intervention or placebo, on healthy children up to 15 years of age.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the methodological quality of the included studies. We grouped studies for quantitative analysis according to study design, vaccine type (MMR, MMRV, MMR+V), virus strain, and study settings. Outcomes of interest were cases of measles, mumps, rubella, and varicella, and harms. Certainty of evidence of was rated using GRADE.

MAIN RESULTS

We included 138 studies (23,480,668 participants). Fifty-one studies (10,248,159 children) assessed vaccine effectiveness and 87 studies (13,232,509 children) assessed the association between vaccines and a variety of harms. We included 74 new studies to this 2019 version of the review. Effectiveness Vaccine effectiveness in preventing measles was 95% after one dose (relative risk (RR) 0.05, 95% CI 0.02 to 0.13; 7 cohort studies; 12,039 children; moderate certainty evidence) and 96% after two doses (RR 0.04, 95% CI 0.01 to 0.28; 5 cohort studies; 21,604 children; moderate certainty evidence). The effectiveness in preventing cases among household contacts or preventing transmission to others the children were in contact with after one dose was 81% (RR 0.19, 95% CI 0.04 to 0.89; 3 cohort studies; 151 children; low certainty evidence), after two doses 85% (RR 0.15, 95% CI 0.03 to 0.75; 3 cohort studies; 378 children; low certainty evidence), and after three doses was 96% (RR 0.04, 95% CI 0.01 to 0.23; 2 cohort studies; 151 children; low certainty evidence). The effectiveness (at least one dose) in preventing measles after exposure (post-exposure prophylaxis) was 74% (RR 0.26, 95% CI 0.14 to 0.50; 2 cohort studies; 283 children; low certainty evidence). The effectiveness of Jeryl Lynn containing MMR vaccine in preventing mumps was 72% after one dose (RR 0.24, 95% CI 0.08 to 0.76; 6 cohort studies; 9915 children; moderate certainty evidence), 86% after two doses (RR 0.12, 95% CI 0.04 to 0.35; 5 cohort studies; 7792 children; moderate certainty evidence). Effectiveness in preventing cases among household contacts was 74% (RR 0.26, 95% CI 0.13 to 0.49; 3 cohort studies; 1036 children; moderate certainty evidence). Vaccine effectiveness against rubella is 89% (RR 0.11, 95% CI 0.03 to 0.42; 1 cohort study; 1621 children; moderate certainty evidence). Vaccine effectiveness against varicella (any severity) after two doses in children aged 11 to 22 months is 95% in a 10 years follow-up (rate ratio (rr) 0.05, 95% CI 0.03 to 0.08; 1 RCT; 2279 children; high certainty evidence). Safety There is evidence supporting an association between aseptic meningitis and MMR vaccines containing Urabe and Leningrad-Zagreb mumps strains, but no evidence supporting this association for MMR vaccines containing Jeryl Lynn mumps strains (rr 1.30, 95% CI 0.66 to 2.56; low certainty evidence). The analyses provide evidence supporting an association between MMR/MMR+V/MMRV vaccines (Jeryl Lynn strain) and febrile seizures. Febrile seizures normally occur in 2% to 4% of healthy children at least once before the age of 5. The attributable risk febrile seizures vaccine-induced is estimated to be from 1 per 1700 to 1 per 1150 administered doses. The analyses provide evidence supporting an association between MMR vaccination and idiopathic thrombocytopaenic purpura (ITP). However, the risk of ITP after vaccination is smaller than after natural infection with these viruses. Natural infection of ITP occur in 5 cases per 100,000 (1 case per 20,000) per year. The attributable risk is estimated about 1 case of ITP per 40,000 administered MMR doses. There is no evidence of an association between MMR immunisation and encephalitis or encephalopathy (rate ratio 0.90, 95% CI 0.50 to 1.61; 2 observational studies; 1,071,088 children; low certainty evidence), and autistic spectrum disorders (rate ratio 0.93, 95% CI 0.85 to 1.01; 2 observational studies; 1,194,764 children; moderate certainty). There is insufficient evidence to determine the association between MMR immunisation and inflammatory bowel disease (odds ratio 1.42, 95% CI 0.93 to 2.16; 3 observational studies; 409 cases and 1416 controls; moderate certainty evidence). Additionally, there is no evidence supporting an association between MMR immunisation and cognitive delay, type 1 diabetes, asthma, dermatitis/eczema, hay fever, leukaemia, multiple sclerosis, gait disturbance, and bacterial or viral infections.

AUTHORS' CONCLUSIONS

Existing evidence on the safety and effectiveness of MMR/MMRV vaccines support their use for mass immunisation. Campaigns aimed at global eradication should assess epidemiological and socioeconomic situations of the countries as well as the capacity to achieve high vaccination coverage. More evidence is needed to assess whether the protective effect of MMR/MMRV could wane with time since immunisation.

Measles and rubella immunity in the population of Bhutan, 2017

BACKGROUND

In 2017, measles elimination was verified in Bhutan, and the country appears to have sufficiently high vaccination coverage to achieve rubella elimination. However, a measles and rubella serosurvey was conducted to find if any hidden immunity gaps existed that could threaten Bhutan's elimination status.

METHODS

A nationwide, three-stage, cluster seroprevalence survey was conducted among individuals aged 1-4, 5-17, and >20 years in 2017. Demographic information and children's vaccination history were collected, and a blood specimen was drawn. Serum was tested for measles and rubella immunoglobulin G (IgG). Frequencies, weighted proportions, and prevalence ratios for measles and rubella seropositivity were calculated by demographic and vaccination history, taking into account the study design.

RESULTS

Of the 1325 individuals tested, 1045 (81%, 95% CI 78%-85%) were measles IgG seropositive, and 1290 (97%, 95% CI 95%-99%) were rubella IgG seropositive. Rubella IgG seropositivity was high in all three age strata, but only 47% of those aged 5-17 years were measles IgG seropositive. Additionally, only 41% of those aged 5-17 years who had documented receipt of two doses of measles- or measles-rubella-containing vaccine were seropositive for measles IgG, but almost all these children were rubella IgG seropositive.

CONCLUSIONS

An unexpected measles immunity gap was identified among children 5-17 years of age. It is unclear why this immunity gap exists; however, it could have led to a large outbreak and threatened sustaining of measles elimination in Bhutan. Based on this finding, a mass vaccination campaign was conducted to close the immunity gap.

Assessing measles vaccine failure in Tianjin, China

Despite increasing global measles vaccination coverage, progress toward measles elimination has slowed in recent years. In China, children receive a measles-containing vaccine (MCV) at 8 months, 18-24 months, and some urban areas offer a third dose at age 4-6 years. However, substantial measles cases in Tianjin, China, occur among individuals who have received multiple MCV doses. This study describes the vaccination history of measles cases 8 months - 19 years old. Data came from measles cases in Tianjin's reportable disease surveillance system (2009-2013), and from a case control study (2011-2015). Twenty-nine percent of those in the surveillance dataset and 54.4% of those in the case series received at least one dose of MCV. The minimum and median time-to-diagnosis since vaccination revealed an increase in time since vaccination for incremental doses. Considerable measles cases in Tianjin occur in vaccinated children, and further research is needed to understand the reasons for vaccine failure.

Mass gatherings medicine: public health issues arising from mass gathering religious and sporting events

Mass gathering events are associated with major public health challenges. The 2014 Lancet Series on the new discipline of mass gatherings medicine was launched at the World Health Assembly of Ministers of Health in Geneva in May, 2014. The Series covered the planning and surveillance systems used to monitor public health risks, public health threats, and experiences of health-care providers from mass gathering events in 2012 and 2013. This follow-up Review focuses on the main public health issues arising from planned mass gathering events held between 2013 and 2018. We highlight public health and research data on transmission of infectious diseases and antibiotic-resistant bacteria, mass casualty incidents, and non-communicable diseases, including thermal disorders. In the events discussed in this Review, the combination of a large influx of people, many from countries with outbreak-prone infectious diseases, with a high degree of crowd interactions imposed substantial burdens on host countries' health systems. The detection and transmission of antibiotic-resistant bacteria in pilgrims attending the Kumbh Mela and the Hajj raise concern of possible globalisation from mass-gathering religious events. Priorities for further investments and opportunities for research into prevention, surveillance, and management of these public health issues are discussed.

Modified Measles in an Anti-Measles Immunoglobulin G-negative Healthcare Worker who had Received Two Doses of Measles-Containing Vaccine

To date, documentation of two doses of measles-containing vaccine (MCV) has been accepted as confirmation of measles immunity among healthcare workers (HCWs). However, we encountered measles in an HCW who had received two doses of MCV. A patient with measles was admitted to our hospital. Among 62 exposed HCWs, one nurse who had previously received two doses of MCV was shown to be negative for anti-measles immunoglobulin G (IgG), and was confirmed to have measles 14 days after exposure. Based on this experience, we suggest that all HCWs should be tested for anti-measles IgG to confirm their immunity to measles.

Impact of Public Health Responses During a Measles Outbreak in an Amish Community in Ohio: Modeling the Dynamics of Transmission

We quantified measles transmissibility during a measles outbreak in Ohio in 2014 to evaluate the impact of public health responses. Case incidence and the serial interval (time between symptom onset in primary cases and secondary cases) were used to assess trends in the effective reproduction number R (the average number of secondary cases generated per case). A mathematical model was parameterized using early R values to determine the size and duration of the outbreak that would have occurred if containment measures had not been initiated, as well as the impact of vaccination. As containment started, we found a 4-fold decline in R (from approximately 4 to 1) over the course of 2 weeks and maintenance of R < 1 as control measures continued. Under a conservative scenario, the model estimated 8,472 cases (90% confidence interval (CI): 8,447, 8,489) over 195 days (90% CI: 179, 223) without control efforts and 715 cases (90% CI: 103, 1,338) over 128 days (90% CI: 117, 139) when vaccination was included; 7,757 fewer cases (90% CI: 7,130, 8,365) and 67 fewer outbreak days (90% CI: 48, 98) were attributed to vaccination. Vaccination may not account entirely for transmission reductions, suggesting that changes in community behavior (social distancing) and other control efforts (isolation, quarantining) are important. Our findings highlight the benefits of measles outbreak response and of understanding behavior change dynamics.

Public health responses during measles outbreaks in elimination settings: Strategies and challenges

In late September 2016, the Americas became the first region in the world to have eliminated endemic transmission of measles virus. Several other countries have also verified measles elimination, and countries in all six World Health Organization regions have adopted measles elimination goals. The public health strategies used to respond to measles outbreaks in elimination settings are thus becoming relevant to more countries. This review highlights the strategies used to limit measles spread in elimination settings: (1) assembly of an outbreak control committee; (2) isolation of measles cases while infectious; (3) exclusion and quarantining of individuals without evidence of immunity; (4) vaccination of susceptible individuals; (5) use of immunoglobulin to prevent measles in exposed susceptible high-risk persons; (6) and maintaining laboratory proficiency for confirmation of measles. Deciding on the extent of containment efforts should be based on the expected benefit of reactive interventions, balanced against the logistical challenges in implementing them.

Identifying risk factors associated with acquiring measles in an outbreak among age-appropriately vaccinated school children: a cohort analysis

BACKGROUND

A measles outbreak occurred in age-appropriately vaccinated children in a school in a town in the South East of Ireland in September-November 2013.

AIMS

The purpose of this study was to investigate the risk factors associated with catching measles during the outbreak.

METHODS

Ninety-five children (4-5 years) in three classes, in the first year of primary school, were included in the study. Immunisation records on the South East Child Health Information System for first Measles Mumps and Rubella (MMR) vaccine for the 95 children were reviewed. Data collected included age at MMR, date of administration of MMR, MMR brand and batch number, and the General Practice at which MMR was administered. The risk factors analysed included age at vaccination, time of vaccination, class and the GP practice where MMR was administered. Statistical analysis was performed using Epi info 7 and SPSS v24.

RESULTS

Thirteen children in the cohort developed measles during the outbreak. All children in the cohort were age-appropriately vaccinated, with one dose of MMR vaccine. Analysis demonstrated statistically significant differences in the relative risk of developing measles according to the class a child was in, and the General Practice at which they were vaccinated.

CONCLUSIONS

The reason for intense measles activity in one class was not established. Although a concurrent investigation into cold chain and vaccine stock management did not identify a cause for the high relative risk of measles in children vaccinated, recommendations were made for improving cold chain and vaccine stock management in General Practices.

Public health response to a measles outbreak on a university campus in Australia, 2015

This report describes the effective public health response to a measles outbreak involving a university campus in Brisbane, Australia. Eleven cases in total were notified, mostly university students. The public health response included targeted measles vaccination clinics which were established on campus and focused on student groups most likely to have been exposed. The size of the university population, social interaction between students on and off campus, as well as limited vaccination records for the university community presented challenges for the control of this extremely infectious illness. We recommend domestic students ensure vaccinations are current prior to matriculation. Immunisation information should be included in university student enrolment packs. Incoming international students should ensure routine vaccinations are up-to-date prior to arrival in Australia, thereby reducing the risk of importation of measles and other infectious diseases.

Cost of a measles outbreak in a remote island economy: 2014 Federated States of Micronesia measles outbreak

After 20years with no reported measles cases, on May 15, 2014 the Centers for Disease Control and Prevention (CDC) was notified of two cases testing positive for measles-specific immunoglobulin M (IgM) antibodies in the Federated States of Micronesia (FSM). Under the Compact of Free Association, FSM receives immunization funding and technical support from the United States (US) domestic vaccination program managed by the Centers for Disease Control and Prevention (CDC). In a collaborative effort, public health officials and volunteers from FSM and the US government worked to respond and contain the measles outbreak through an emergency mass vaccination campaign, contact tracing, and other outbreak investigation activities. Contributions were also made by United Nations Children's Emergency Fund (UNICEF) and World Health Organization (WHO). Total costs incurred as a result of the outbreak were nearly $4,000,000; approximately $10,000 per case. Direct medical costs (≈$141,000) were incurred in the treatment of those individuals infected, as well as lost productivity of the infected and informal caregivers (≈$250,000) and costs to contain the outbreak (≈$3.5 million). We assessed the economic burden of the 2014 measles outbreak to FSM, as well as the economic responsibilities of the US. Although the US paid the majority of total costs of the outbreak (≈67%), examining each country's costs relative to their respective economy illustrates a far greater burden to FSM. We demonstrate that while FSM was heavily assisted by the US in responding to the 2014 Measles Outbreak, the outbreak significantly impacted their economy. FSM's economic burden from the outbreak is approximately equivalent to their entire 2016 Fiscal Year budget dedicated to education.

Perspective on Global Measles Epidemiology and Control and the Role of Novel Vaccination Strategies

Measles is a highly contagious, vaccine preventable disease. Measles results in a systemic illness which causes profound immunosuppression often leading to severe complications. In 2010, the World Health Assembly declared that measles can and should be eradicated. Measles has been eliminated in the Region of the Americas, and the remaining five regions of the World Health Organization (WHO) have adopted measles elimination goals. Significant progress has been made through increased global coverage of first and second doses of measles-containing vaccine, leading to a decrease in global incidence of measles, and through improved case based surveillance supported by the WHO Global Measles and Rubella Laboratory Network. Improved vaccine delivery methods will likely play an important role in achieving measles elimination goals as these delivery methods circumvent many of the logistic issues associated with subcutaneous injection. This review highlights the status of global measles epidemiology, novel measles vaccination strategies, and describes the pathway toward measles elimination.