Higher risk of measles when the first dose of a 2-dose schedule of measles vaccine is given at 12-14 months versus 15 months of age

A neutralizing antibody prevents postfusion transition of measles virus fusion protein

Measles virus (MeV) presents a public health threat that is escalating as vaccine coverage in the general population declines and as populations of immunocompromised individuals, who cannot be vaccinated, increase. There are no approved therapeutics for MeV. Neutralizing antibodies targeting viral fusion are one potential therapeutic approach but have not yet been structurally characterized or advanced to clinical use. We present cryo-electron microscopy (cryo-EM) structures of prefusion F alone [2.1-angstrom (Å) resolution], F complexed with a fusion-inhibitory peptide (2.3-Å resolution), F complexed with the neutralizing and protective monoclonal antibody (mAb) 77 (2.6-Å resolution), and an additional structure of postfusion F (2.7-Å resolution). In vitro assays and examination of additional EM classes show that mAb 77 binds prefusion F, arrests F in an intermediate state, and prevents transition to the postfusion conformation. These structures shed light on antibody-mediated neutralization that involves arrest of fusion proteins in an intermediate state.

The decline of measles antibody titers in previously vaccinated adults: a cross-sectional analysis

The global reemergence of measles in 2018-2019 reinforces the relevance of high-coverage immunization to maintain the disease elimination. During an outbreak in the Sao Paulo State in 2019, several measles cases were reported in individuals who were adequately vaccinated according to the current immunization schedule recommends. This study aimed to assess measles IgG antibody seropositivity and titers in previously vaccinated adults. A cross-sectional study was conducted at CRIE-HC-FMUSP (Sao Paulo, Brazil) in 2019. It included healthy adults who had received two or more Measles-Mumps-Rubella vaccines (MMR) and excluded individuals with immunocompromising conditions. Measles IgG antibodies were measured and compared by ELISA (Euroimmun®) and chemiluminescence (LIASON®). The association of seropositivity and titers with variables of interest (age, sex, profession, previous measles, number of measles-containing vaccine doses, interval between MMR doses, and time elapsed since the last MMR dose) was analyzed. A total of 162 participants were evaluated, predominantly young (median age 30 years), women (69.8%) and healthcare professionals (61.7%). The median interval between MMR doses was 13.2 years, and the median time since the last dose was 10.4 years. The seropositivity rate was 32.7% by ELISA and 75.3% by CLIA, and a strong positive correlation was found between the tests. Multivariate analyses revealed that age and time since the last dose were independently associated with positivity. Despite being a single-center evaluation, our results suggest that measles seropositivity may be lower than expected in adequately immunized adults. Seropositivity was higher among older individuals and those with a shorter time since the last MMR vaccine dose.

Seroepidemiology of measles in immune generation in Taiwan: Prevalence of neutralizing antibody and immune response to reimmunization

BACKGROUND

Secondary vaccine failure was the principal mechanic of measles reemergence in countries with high measles vaccine coverage. The information on neutralizing antibody (nAb) prevalence, epidemiological factors of waned immunity and immune response after reimmunization was essential to measles control but largely lacking in Taiwan.

METHODS

The nAb and factors of wanned immunity to measles were evaluated in a cohort of 333 subjects aged 11-30 years in 2010. The longitudinal immune response to reimmunization (n = 30) and potential virus exposure (n = 24) were assessed in young healthcare workers (HCWs) during a hospital outbreak. The nAb titer was used to define susceptibility to measles disease (<120 mIU/mL) and infection (120-900 mIU/mL).

RESULTS

In the 2010 cohort, the susceptibility to measles diseases and infections was respectively identified in 35 (10.5%) and 226 (67.9%) subjects. A generalized linear model identified earlier ages of first immunization in childhood (P = 0.0214) and subjects aged ≥18 years (versus <18 years, P = 0.0425) as significant factors associated with lower nAb titers. Reimmunization of 30 seronegative HCWs resulted in seroconversion for all, with nAb titers significantly rising on day 5, peaking on day 15 and declining in month 4 post-immunization. Similar measles-specific IgG levels were observed in 24 seropositive HCWs before and 4 months after measles contact (P = 0.2352).

CONCLUSION

A lack of protective immunity to measles diseases might be identified in 10% of the Taiwanese population aged 11-30 years and associated with a trend toward earlier ages of the first measles vaccination. The wanned immunity can be boosted promptly by reimmunization but with uncertain durability.

Etiological analysis of discarded measles in the context of a measles outbreak among a highly immunized population

BACKGROUND

Measles can lead to serious complications and remains an important cause of morbidity and mortality worldwide. In this study we aimed to assess the etiological diagnosis of discarded measles cases in the context of an outbreak among a highly immunized population.

METHODS

We conducted a retrospective observational study of discarded measles cases from an outbreak that occurred from October 2006 to July 2007 in Catalonia. A confirmed case was defined as having a positive measles serum IgM result and/or a positive result by RT-PCR in urine and/or nasopharyngeal swab; or an epidemiological link to a confirmed case. Serum specimens were tested by a commercially available indirect-format and by an in-house capture-format measles IgM enzyme immunoassays.

RESULTS

Testing of 89 samples discarded for measles determined the etiologies for 10 (11.2%), including one rubella, three human herpes virus 6, and six measles infections. Of 381 confirmed cases in the outbreak, 10% had received at least one dose of the measles-mumps-rubella vaccine versus 54% of the discarded for measles (OR: 0.09; 95% CI: 0.06, 0.14; p < 0.001).

CONCLUSIONS

Highly sensitive surveillance systems are critical to identifying cases, responding to outbreaks and verifying progress towards measles elimination. Molecular tools for measles detection and differential diagnosis, and collection of appropriate specimens for molecular and serological testing are essential to correctly diagnose suspected measles infection.

Population immunity to measles in Canada using Canadian Health Measures survey data - A Canadian Immunization Research Network (CIRN) study

We aimed to determine population immunity to measles in Canada, and to assess the risk of future outbreaks. We tested 11,176 sera from Cycles 2 (2009-2011) and 3 (2011-2013) cohorts from the biobank of Statistics Canada's Canadian Health Measures Survey (CHMS) using the BioPlex 2220 MMRV IgG assay. We then tested all BioPlex negative and equivocal samples using a more sensitive Plaque Reduction Neutralization Test (PRNT). We determined the weighted proportion of positive, equivocal, and negative samples by age, sex, region and whether individuals were born in Canada. We found that 90.0% (95% confidence interval (CI): 88.2, 91.9) of samples were positive, 4.5% (95% CI: 3.4, 5.5) were equivocal and 5.5% (95% CI: 4.3, 6.7) were negative. Individuals in the 12-19 year age band had the lowest proportion positive at 78.7% (95% CI: 74.2, 83.2) and the highest proportion of positive samples was found in those 60-79 years (99.6%, 95% CI: 99.3, 99.9). Seropositivity was consistently <90% across a broad range of pediatric and adult age bands (6-39 years). We found that a slightly higher proportion of females were positive (91.9%, 95% CI: 90.1, 93.6) compared to males (88.3%, 95% CI: 85.8, 90.7). When taking into account interaction between age and born in Canada status, we found individuals born in Canada aged 19 and under were less susceptible (OR = 0.6 (95% CI: 0.4, 0.95)) compared to those born outside Canada whereas, those aged 20 and over were more susceptible (OR = 1.7 (95% CI: 1.1, 2.8)). Our findings indicate that measles immunity in Canada is below the 95% immunity threshold required to sustain measles elimination, underscoring the importance of maintaining high vaccine coverage to prevent future measles outbreaks and sustain Canada's elimination status.

Comparative study on molecular epidemiology of measles H1 outbreak and sporadic cases in Shandong Province, 2013–2019

Background

Measles caused by measles virus (MeV) is a highly contagious viral disease which has also been associated with complications including pneumonia, myocarditis, encephalitis, and subacute sclerosing panencephalitis. The current study isolated 33 strains belonging to 2 groups, outbreak and sporadic strains, in 13 cities of Shandong province, China from 2013 to 2019. Comparison of genetic characterization among 15 outbreak strains and 18 sporadic strains was performed by analyzing nucleotide sequences of the C-terminal region of N protein gene (N-450).

Results

All 33 stains belonged to genotype H1. The outbreak strains and sporadic strains distributed crossly in phylogenetic tree. Sequences alignment revealed some interesting G to A transversion which changed the amino acids on genomic sites 1317, 1422, and 1543. The nucleotide and amino acid similarities among outbreak isolates were 98–100% (0–10 nucleotide variations) and 97.7–100%, respectively; They were 97.3–100% and 96.6–100%, respectively for sporadic isolates. Evolutionary genetics analysis revealed that the mean evolution rates of outbreak and sporadic isolates were 1.26 N 10− 3 and 1.48 N 10− 3 substitutions per site per year separately, which were similar with corresponding data before 2012. Local transmission analysis suggested that there were three transmission chains in this study, two of them originated from Japan. Outbreak cases and sporadic cases emerged alternatively and were reciprocal causation on the transmission chains.

Conclusions

Our study investigated the phylogeny and evolutional genetics of MeV during a 7-year surveillance, and compared epidemic and genetic characteristics of outbreak strains and sporadic strains. These results underscore the importance of evolutionary study alongside with sporadic cases in discovering and tracing possible outbreaks, especially in the stage of measles elimination.

Prevention of measles, mumps and rubella: 40 years of global experience with M-M-RII

Measles, mumps, and rubella are highly contagious diseases that caused significant global mortality and morbidity in the pre-vaccine era. Since its first approval in the United States over 40 years ago, M-M-RII has been used in >75 countries for prevention of these diseases. The vaccine has been part of immunization programs that have achieved dramatic global reductions in case numbers and mortality rates, as well as the elimination of measles and rubella in several countries and regions. This report summarizes over four decades of global safety, immunogenicity, efficacy, and effectiveness data for the vaccine. We include studies on the use of M-M-RII in different age groups, concomitant use with other routine childhood vaccines, administration via different routes, persistence of immunity, and vaccine effectiveness during outbreaks of measles and mumps. We conclude that M-M-RII is well tolerated and has shown consistently high performance during routine use in multiple countries, in randomized controlled trials with diverse designs, and in outbreak settings, including use as measles postexposure prophylaxis. Physicians, parents, and the public can continue to have a high degree of confidence in the use of M-M-RII as a vital part of global public health programs.

Report of the Korean Society of Infectious Diseases Roundtable Discussion on Responses to the Measles Outbreaks in Korea in 2019

During the 2019 domestic measles outbreak in Korea, measles occurred in healthcare workers with two doses of the measles, mumps and rubella vaccine, and the strict application of the Occupational Safety and Health Act required medical institutions to identify healthcare workers' immunity to measles and vaccinate the susceptible pockets. In response to the frontline medical institutions' request to review the measles recommendations and guidelines, the Korean Society of Infectious Diseases held a roundtable discussion on the causes of measles outbreak, timing of vaccinations, antibody tests, and booster vaccinations for healthcare workers, and financial support from the government and municipality as well as response strategies against the outbreak in healthcare settings. In Korea, the seroprevalence of measles is decreasing in the vaccine-induced immunity group during the maintenance of measles elimination over several years. The susceptible group against measles is in their 20s and 30s, and this may be because of waning immunity rather than non-response considering Korea's vaccine policy. The risk of measles nosocomial infection from community increases as these susceptible pockets actively engage in medical institutions. Thus, data on the immunity of low seroprevalence group in Korea are needed, further discussion is needed on the booster vaccination based on the data. Especially, antibody testing and vaccination in healthcare workers may be necessary to prevent the spread of measles in medical insutitutions, and further discussion is needed regarding specific testing methods, and the timing and frequency of test and vaccination.

Waning immunity and potential asymptomatic infection in 3-7 years old children who received one dose of measles-mumps-rubella vaccine: A 4-year prospective study

BACKGROUND

Mumps outbreaks in adolescents who received two doses of measles-mumps-rubella vaccine (MMR) during childhood have been reported worldwide. In China, one dose of MMR administered in children aged among 18-24 months has a limited effect on the mumps epidemic. There are limited prospective studies evaluating the mumps immunity profile of children aged 3-7 years who received one dose of MMR. This study aimed to describe mumps immunity profile over a span of 4-years in kindergarten and primary school children.

METHODS

An observational, prospective study on one-dose MMR in children aged 3-7 years who underwent blood sample collection in 2015, 2016, and 2018 was conducted from 2015 to 2018. The seropositivity and geometric mean concentration of mumps IgG antibodies over time were analyzed.

RESULTS

A total of 3346 eligible children aged 3-7 years who underwent three rounds of blood sample collection were included. The overall seropositivity (79.6%) in 2015 was significantly higher than those recorded in 2016 (73.1%) and 2018 (71.4%). Approximately 11.6-15.9% of the participants were seropositive for mumps in 2015, and converted to negative in 2016. Meanwhile, 11.1-14.6% of the participants were seropositive for mumps in 2016, and the results converted to negative in 2018. Over 6.1-7.4% of the participants had asymptomatic infection from 2015 to 2016, while 9.0-9.9% of the participants were infected without clinical symptoms from 2016 to 2018.

CONCLUSIONS

Kindergarten and primary school children who only received one dose of MMR were at higher risk of developing mumps. Waning immunity, seronegative conversion, and asymptomatic infection coexist in children who received one dose MMR. Determining the optimal age for administering the second dose of MMR in children should be prioritized to improve the control and prevention of mumps in China.

Measles and rubella serosusceptibity among population vaccinated with different schedules: the potential impact on measles-rubella elimination in Iran

BACKGROUND

Iranian children were vaccinated with the scheduled two doses of monovalent measles vaccine (mMV) from 1984. In December 2003, a nationwide campaign of measles-rubella (MR) immunization was established to vaccinate 5-25 year- old individuals. In 2004, the mMV was replaced with measles- mumps- rubella (MMR) vaccine. Despite the high vaccination coverage, the outbreaks of measles still occur in the country. In this Study, the MR immunity status of various age groups, vaccinated with different schedules was investigated, and the immunologic response of seronegative subjects to revaccination was examined.

METHODS

This cross-sectional study was conducted among 7-33-year-old healthy individuals with a documented history of measles vaccination from November 2017 to June 2018. The subjects were categorized as follows: group A, including 20-33 year-old individuals; vaccinated with 1-2 doses of mMV at ages 9 and 15 months, and revaccinated with MR, group B, including 15-19-year-old individuals, vaccinated with two doses of mMV at 9 and 15 months of age, and received additional dose of MMR upon school entrance, group C, including 11-14 year-old individuals, vaccinated with two-doses of MMR at the ages of 15 months and 6 years, and group D, including 7-10 year-old individuals vaccinated with two-doses of MMR vaccine at the ages 12 and 18 months, respectively. Levels of antimeasles- antirubella IgG antibodies in the collected sera were measured. Also antimeasles- antirubella IgM and IgG of seronegative individuals were reexamined at 4-6 weeks after MMR revaccination. The collected data were analyzed using descriptive statistical methods.

RESULTS

A total of 635 individuals were investigated in this study. Group A, 98; group B, 295; group C, 139; and group D, 103 persons. Overall, 12.3 and 18.4% of the population were seronegative for measles and rubella antibodies. This rate varied greatly between the 4 groups: group A, 0/0-2%; group B,15.2-25.0%; group C,11.5-17.2%; and groupD,14.6-18.4%. After revaccination, 92 and 94.9% of seronegative individuals showed IgG response to measles and rubella vaccines, respectively.

CONCLUSION

Despite the high coverage rate of M-R containing vaccines, a significant number of vaccinated subjects were seronegative for measles and rubella, possibly because of secondary vaccine failure; this may negatively affect measles-rubella elimination targets in the country. If these findings are confirmed in similar future studies, a more robust regional/national supplementary immunization activity will be considered.

Cyclic Di-Adenosine Monophosphate: A Promising Adjuvant Candidate for the Development of Neonatal Vaccines

Underdeveloped immunity during the neonatal age makes this period one of the most dangerous during the human lifespan, with infection-related mortality being one of the highest of all age groups. It is also discussed that vaccination during this time window may result in tolerance rather than in productive immunity, thus raising concerns about the overall vaccine-mediated protective efficacy. Cyclic di-nucleotides (CDN) are bacterial second messengers that are rapidly sensed by the immune system as a danger signal, allowing the utilization of these molecules as potent activators of the immune response. We have previously shown that cyclic di-adenosine monophosphate (CDA) is a potent and versatile adjuvant capable of promoting humoral and cellular immunity. We characterize here the cytokine profiles elicited by CDA in neonatal cord blood in comparison with other promising neonatal adjuvants, such as the imidazoquinoline resiquimod (R848), which is a synthetic dual TLR7 and TLR8 agonist. We observed superior activity of CDA in eliciting T helper 1 (Th1) and T follicular helper (TfH) cytokines in cells from human cord blood when compared to R848. Additional in vivo studies in mice showed that neonatal priming in a three-dose vaccination schedule is beneficial when CDA is used as a vaccine adjuvant. Humoral antibody titers were significantly higher in mice that received a neonatal prime as compared to those that did not. This effect was absent when using other adjuvants that were reported as suitable for neonatal vaccination. The biological significance of this immune response was assessed by a challenge with a genetically modified influenza H1N1 PR8 virus. The obtained results confirmed that CDA performed better than any other adjuvant tested. Altogether, our results suggest that CDA is a potent adjuvant in vitro on human cord blood, and in vivo in newborn mice, and thus a suitable candidate for the development of neonatal vaccines.

Measles Outbreak at a Privately Operated Detention Facility: Arizona, 2016

BACKGROUND

We describe a measles outbreak and control measures implemented at a privately operated detention facility housing US Immigration and Customs Enforcement detainees in 2016.

METHODS

Case-patients reported fever and rash and were either laboratory-confirmed or had an epidemiological link to a laboratory-confirmed case-patient. Immunoglobulin G (IgG) avidity and plaque reduction neutralization tests distinguished between primary acute and reinfection case-patients. Measles-specific IgG was measured to assess detainee immunity levels. We compared attack rates (ARs) among detainees and staff, between IgG-negative and IgG-positive detainees, and by detainee housing units and sexes.

RESULTS

We identified 32 measles case-patients (23 detainees, 9 staff); rash onsets were during 6 May-26 June 2016. High IgG avidity and neutralizing-antibody titers >40000 to measles (indicating reinfection) were identified in 18 (95%) and 15 (84%) of 19 tested case-patients, respectively. Among 205 unit A detainees tested for presumptive immunity, 186 (91%) had detectable IgG. Overall, the AR was 1.65%. ARs were significantly higher among detainees in unit A (7.05%) compared with units B-F (0.59%), and among male (2.33%) compared with female detainees (0.38%); however, ARs were not significantly different between detainees and staff or between IgG-negative and IgG-positive detainees. Control measures included the vaccination of 1424 of 1425 detainees and 190 of 510 staff, immunity verification for 445 staff, case-patient isolation, and quarantine of affected units.

CONCLUSIONS

Although ARs were low, measles outbreaks can occur in intense-exposure settings, despite a high population immunity, underscoring the importance of high vaccination coverage and containment in limiting measles transmission.

Estimating the nationwide transmission risk of measles in US schools and impacts of vaccination and supplemental infection control strategies

BACKGROUND

The spread of airborne infectious diseases such as measles is a critical public health concern. The U.S. was certified measles-free in 2000, but the number of measles cases has increased in recent years breaking the record of the nationwide annual number of cases since 1992. Although the characteristics of schools have made them one of the most vulnerable environments during infection outbreaks, the transmission risk of measles among students is not completely understood. We aimed to evaluate how three factors influence measles transmission in schools: personal (vaccination), social (compartmentalizing), and building systems (ventilation, purification, and filtration).

METHODS

We used a combination of a newly developed multi-zone transient Wells-Riley approach, a nationwide representative School Building Archetype (SBA) model, and a Monte-Carlo simulation to estimate measles risk among U.S. students. We compared our risk results with the range of reported transmission rates of measles in school outbreaks to validate the risk model. We also investigated the effectiveness of vaccination and ten supplemental infection control scenarios for reducing the risk of measles transmission among students.

RESULTS

Our best nationwide estimate of measles transmission risk in U.S. schools were 3.5 and 32% among all (both unvaccinated and immunized) and unvaccinated students, respectively. The results showed the transmission risk of measles among unvaccinated students is > 70 times higher than properly immunized ones. We also demonstrated that the transmission risk of measles in primary schools (assuming teacher self-contained classrooms) is less than secondary schools (assuming departmentalized systems). For building-level interventions, schools with ductless-with-air-filter and ductless-without-air-filter systems have the lowest and highest transmission risks of measles, respectively. Finally, our simulation showed that infection control strategies could cut the average number of infected cases among all students in half when a combination of advanced air filtration, ventilation, and purification was adopted in the modeled schools.

CONCLUSIONS

Our results highlight the primary importance of vaccination for reducing the risk of measles transmission among students. Yet, additional and significant risk reduction can be achieved through compartmentalizing students and enhancing building ventilation and filtration systems.

The Resurgence of Measles Infection and its Associated Complications in Early Childhood at a Tertiary Care Hospital in Peshawar, Pakistan

Measles infection is of substantial interest to immunologists due to its paradoxical interaction with the immune system. After the acquisition of the measles infection, secondary infection plays a pivotal role in measles-related deaths. A cross-sectional study conducted between December 2018 and July 2019 is presented here. A total of one hundred children of both genders presented with measles complications were included following WHO criteria. Measles confirmation was done by quantitative determination of anti-measles antibodies (IgM) in patients’ sera while patient-related demographic data, vaccination status, and other clinical information were obtained on a separate form. The number of female patients (52%) slightly exceeded the number of males (48%). 43% of patients’ parents were illiterate, and half of the patients (50%) were from a poor background. The majority of children (76%) who presented with the complications did not receive a measles vaccine. 56% of children were breastfed while 58% received vitamin A supplements but developed complications. The elevated levels of anti-measles IgM were observed in 77% of cases. In both genders, the major complications were pneumonia, lower respiratory tract infection (LRTI), acute diarrhea, diarrhea and LRTI, pneumonia and diarrhea, otitis media and pneumonia, myocarditis and LRTI, and pneumothorax. The majority of the infected children (n = 48) under 12 months of age had associated complications. It has been observed that the measles virus strikes early age children in the northwestern region of Pakistan, which is an alarming situation and is associated with the aforementioned complications, especially in unvaccinated children. Anti-measles IgM is an important serological parameter for early diagnosis of measles infection.

Effect of age at vaccination on the measles vaccine effectiveness and immunogenicity: systematic review and meta-analysis

Background

The objectives of this review were to evaluate the effect of age at administration of the first dose of a measles-containing vaccine (MCV1) on protection against measles and on antibody response after one- and two-dose measles vaccinations.

Methods

We conducted a systematic review of the PubMed/MEDLINE, Embase, Web of Science and Cochrane databases (1964–2017) to identify observational studies estimating vaccine effectiveness and/or measles attack rates by age at first vaccination as well as experimental studies comparing seroconversion by age at first vaccination. Random effect models were used to pool measles risk ratios (RR), measles odds ratios (OR) and seroconversion RR of MCV1 administered at < 9, 9–11 or ≥ 15 months compared with 12 or 12–14 months of age.

Results

We included 41 and 67 studies in the measles protection and immunogenicity analyses. Older age at MCV1, from 6 to ≥15 months, improved antibody response and measles protection among one-dose recipients. Pooled measles RR ranged from 3.56 (95%CI: 1.28, 9.88) for MCV1 at < 9 months to 0.48 (95%CI: 0.36, 0.63) for MCV1 at ≥15 months, both compared to 12–14 months. Pooled seroconversion RR ranged from 0.93 (95%CI: 0.90, 0.96) for MCV1 at 9–11 months to 1.03 (95%CI: 1.00, 1.06) for MCV1 at ≥15 months, both compared to 12 months. After a second dose, serological studies reported high seropositivity regardless of age at administration of MCV1 while epidemiological data based on few studies suggested lower protection with earlier age at MCV1.

Conclusions

Earlier age at MCV1 decreases measles protection and immunogenicity after one dose and might still have an impact on vaccine failures after two doses of measles vaccine. While two-dose vaccination coverage is most critical to interrupt measles transmission, older age at first vaccination may be necessary to keep the high level of population immunity needed to maintain it.

Measles: An Overview of a Re-Emerging Disease in Children and Immunocompromised Patients

Despite the availability of a safe and effective vaccine, in 2018, around 350,000 measles cases were reported worldwide, which resulted in an estimate of 142,300 deaths from measles. Additionally, in 2017, global measles cases spiked, causing the death of 110,000 people, mostly children under the age of 5 years and immunocompromised adults. The increase in measles incidence is caused by the ongoing reduction of vaccination coverage. This event has triggered public and scientific interest. For this reason, we reviewed the pathophysiology of measles infection, focusing on mechanisms by which the virus spreads systemically through the host organism. By reaching the lymphocytes from the airways through a "trojan horse" strategy, measles induces an immunosuppression status. H and F glycoproteins, both expressed in the envelope, ensure attachment of the virus to host cells and spreading from one cell to another by binding to several receptors, as described in detail. The severity of the disease depends both on the age and underlying conditions of patients as well as the social and health context in which epidemics spread, and is often burdened by sequelae and complications that may occur several years after infection. Particular attention was paid to special groups that are more susceptible to severe or atypical measles. An overview of microbiology, symptoms, diagnosis, prevention, and treatment completes and enriches the review.

The effect of time since measles vaccination and age at first dose on measles vaccine effectiveness - A systematic review

BACKGROUND

In settings where measles has been eliminated, vaccine-derived immunity may in theory wane more rapidly due to a lack of immune boosting by circulating measles virus. We aimed to assess whether measles vaccine effectiveness (VE) waned over time, and if so, whether differentially in measles-eliminated and measles-endemic settings.

METHODS

We performed a systematic literature review of studies that reported VE and time since vaccination with measles-containing vaccine (MCV). We extracted information on case definition (clinical symptoms and/or laboratory diagnosis), method of vaccination status ascertainment (medical record or vaccine registry), as well as any biases which may have arisen from cold chain issues and a lack of an age at first dose of MCV. We then used linear regression to evaluate VE as a function of age at first dose of MCV and time since MCV.

RESULTS

After screening 14,782 citations, we identified three full-text articles from measles-eliminated settings and 33 articles from measles-endemic settings. In elimination settings, two-dose VE estimates increased as age at first dose of MCV increased and decreased as time since MCV increased; however, the small number of studies available limited interpretation. In measles-endemic settings, one-dose VE increased by 1.5% (95% CI 0.5, 2.5) for every month increase in age at first dose of MCV. We found no evidence of waning VE in endemic settings.

CONCLUSIONS

The paucity of data from measles-eliminated settings indicates that additional studies and approaches (such as studies using proxies including laboratory correlates of protection) are needed to answer the question of whether VE in measles-eliminated settings wanes. Age at first dose of MCV was the most important factor in determining VE. More VE studies need to be conducted in elimination settings, and standards should be developed for information collected and reported in such studies.

Factors Associated With Measles Transmission in the United States During the Postelimination Era

IMPORTANCE

Measles cases and outbreaks continue to occur in the United States after the introduction of measles from endemic settings.

OBJECTIVE

To discern the factors associated with measles transmission in the United States after measles had been eliminated.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study was conducted from January 1, 2001, to December 31, 2017, in the United States among US residents and international visitors with confirmed measles. A maximum likelihood algorithm that uses the observed dates of rash onset and the known distribution of the serial interval (time between symptom onset in related consecutive cases) was applied to outbreak notification data to estimate the effective reproduction number (R), or the mean number of new infections generated per case. Transmissibility was assessed by comparing R based on the characteristics of primary and secondary cases of measles.

EXPOSURES

Measles virus.

MAIN OUTCOMES AND MEASURES

Effective reproduction number (R), or the mean number of successful transmission events per case of measles (ie, the mean number of persons to whom each patient with measles spreads measles).

RESULTS

A total of 2218 individuals with confirmed measles cases (1025 female, 1176 male, and 17 sex not reported; median age, 15 years [range, 0-89 years]) reported from 2001 to 2017 were evaluated. Among patients who received no doses of measles vaccine, R was 0.76 (95% CI, 0.71-0.81); among patients who received 1 dose of measles vaccine, R was 0.17 (95% CI, 0.11-0.26); among patients who received 2 doses or more of measles vaccine, R was 0.27 (95% CI, 0.17-0.39); and among patients with unknown vaccination status, R was 0.52 (95% CI, 0.44-0.60). Among patients born before 1957, R was 0.35 (95% CI, 0.20-0.58), and among those born on or after 1957, R was 0.64 (95% CI, 0.61-0.68). R was higher when primary and secondary cases of measles were patients aged 5 to 17 years (0.36 [95% CI, 0.31-0.42]) compared with assortative transmission in other age groups (<1 year, 0.14 [95% CI, 0.10-0.20]; 1-4 years, 0.25 [95% CI, 0.20-0.30]; 18-29 years, 0.19 [95% CI, 0.15-0.24]; 30-49 years, 0.15 [95% CI, 0.11-0.20]; ≥50 years, 0.04 [95% CI, 0.01-0.10]).

CONCLUSIONS AND RELEVANCE

The findings of this study support having high targets for 2-dose measles vaccine coverage, particularly among school-aged children in the United States.

Immunogenicity, effectiveness, and safety of measles vaccination in infants younger than 9 months: a systematic review and meta-analysis

BACKGROUND

Measles is an important cause of death in children, despite the availability of safe and cost-saving measles-containing vaccines (MCVs). The first MCV dose (MCV1) is recommended at 9 months of age in countries with ongoing measles transmission, and at 12 months in countries with low risk of measles. To assess whether bringing forward the age of MCV1 is beneficial, we did a systematic review and meta-analysis of the benefits and risks of MCV1 in infants younger than 9 months.

METHODS

For this systematic review and meta-analysis, we searched MEDLINE, EMBASE, Scopus, Proquest, Global Health, the WHO library database, and the WHO Institutional Repository for Information Sharing database, and consulted experts. We included randomised and quasi-randomised controlled trials, outbreak investigations, and cohort and case-control studies without restriction on publication dates, in which MCV1 was administered to infants younger than 9 months. We did the literature search on June 2, 2015, and updated it on Jan 14, 2019. We assessed: proportion of infants seroconverted, geometric mean antibody titre, avidity, cellular immunity, duration of immunity, vaccine efficacy, vaccine effectiveness, and safety. We used random-effects models to derive pooled estimates of the endpoints, where appropriate. We assessed methodological quality using the Grading of Recommendations, Assessment, Development, and Evaluation guidelines.

FINDINGS

Our search identified 1156 studies, of which 1071 were screened for eligibility. 351 were eligible for full-text screening, and data from 56 studies that met all inclusion criteria were used for analysis. The proportion of infants who seroconverted increased from 50% (95% CI 29-71) for those vaccinated with MCV1 at 4 months of age to 85% (69-97) for those were vaccinated at 8 months. The pooled geometric mean titre ratio for infants aged 4-8 months vaccinated with MCV1 compared with infants vaccinated with MCV1 at age 9 months or older was 0·46 (95% CI 0·33-0·66; I2=99·9%, p<0·0001). Only one study reported on avidity and suggested that there was lower avidity and a shorter duration of immunity following MCV1 administration at 6 months of age than at 9 months of age (p=0·0016) or 12 months of age (p<0·001). No effect of age at MCV1 administration on cellular immunity was found. One study reported that vaccine efficacy against laboratory-confirmed measles virus infection was 94% (95% CI 74-98) in infants vaccinated with MCV1 at 4·5 months of age. The pooled vaccine effectiveness of MCV1 in infants younger than 9 months against measles was 58% (95% CI 9-80; I2=84·9%, p<0·0001). The pooled vaccine effectiveness estimate from within-study comparisons of infants younger than 9 months vaccinated with MCV1 were 51% (95% CI -44 to 83; I2=92·3%, p<0·0001), and for those aged 9 months and older at vaccination it was 83% (76-88; I2=93·8%, p<0·0001). No differences in the risk of adverse events after MCV1 administration were found between infants younger than 9 months and those aged 9 months of older. Overall, the quality of evidence ranged from moderate to very low.

INTERPRETATION

MCV1 administered to infants younger than 9 months induces a good immune response, whereby the proportion of infants seroconverted increases with increased age at vaccination. A large proportion of infants receiving MCV1 before 9 months of age are protected and the vaccine is safe, although higher antibody titres and vaccine effectiveness are found when MCV1 is administered at older ages. Recommending MCV1 administration to infants younger than 9 months for those at high risk of measles is an important step towards reducing measles-related mortality and morbidity.

FUNDING

WHO.

Effect of measles vaccination in infants younger than 9 months on the immune response to subsequent measles vaccine doses: a systematic review and meta-analysis

BACKGROUND

Vaccinating infants with a first dose of measles-containing vaccine (MCV1) before 9 months of age in high-risk settings has the potential to reduce measles-related morbidity and mortality. However, there is concern that early vaccination might blunt the immune response to subsequent measles vaccine doses. We systematically reviewed the available evidence on the effect of MCV1 administration to infants younger than 9 months on their immune responses to subsequent MCV doses.

METHODS

For this systematic review and meta-analysis, we searched for randomised and quasi-randomised controlled trials, outbreak investigations, and cohort and case-control studies without restriction on publication dates, in which MCV1 was administered to infants younger than 9 months. We did the literature search on June 2, 2015, and updated it on Jan 14, 2019. We included studies reporting data on strength or duration of humoral and cellular immune responses, and on vaccine efficacy or vaccine effectiveness after two-dose or three-dose MCV schedules. Our outcome measures were proportion of seropositive infants, geometric mean titre, vaccine efficacy, vaccine effectiveness, antibody avidity index, and T-cell stimulation index. We used random-effects meta-analysis to derive pooled estimates of the outcomes, where appropriate. We assessed the methodological quality of included studies using Grading of Recommendation Assessment, Development and Evaluation (GRADE) guidelines.

FINDINGS

Our search retrieved 1156 records and 85 were excluded due to duplication. 1071 records were screened for eligibility, of which 351 were eligible for full-text screening and 21 were eligible for inclusion in the review. From 13 studies, the pooled proportion of infants seropositive after two MCV doses, with MCV1 administered before 9 months of age, was 98% (95% CI 96-99; I²=79·8%, p<0·0001), which was not significantly different from seropositivity after a two-dose MCV schedule starting later (p=0·087). Only one of four studies found geometric mean titres after MCV2 administration to be significantly lower when MCV1 was administered before 9 months of age than at 9 months of age or later. There was insufficient evidence to determine an effect of age at MCV1 administration on antibody avidity. The pooled vaccine effectiveness estimate derived from two studies of a two-dose MCV schedule with MCV1 vaccination before 9 months of age was 95% (95% CI 89-100; I²=12·6%, p=0·29). Seven studies reporting on measles virus-specific cellular immune responses found that T-cell responses and T-cell memory were sustained, irrespective of the age of MCV1 administration. Overall, the quality of evidence was moderate to very low.

INTERPRETATION

Our findings suggest that administering MCV1 to infants younger than 9 months followed by additional MCV doses results in high seropositivity, vaccine effectiveness, and T-cell responses, which are independent of the age at MCV1, supporting the vaccination of very young infants in high-risk settings. However, we also found some evidence that MCV1 administered to infants younger than 9 months resulted in lower antibody titres after one or two subsequent doses of MCV than when measles vaccination is started at age 9 months or older. The clinical and public-health relevance of this immunity blunting effect are uncertain.

FUNDING

WHO.

Promoting vaccination in the province of Québec: the PromoVaQ randomized controlled trial protocol

Background

Vaccination has a huge public health impact. Maintaining vaccine coverage is key to avoid the devastating consequences of resurgence. In the Province of Québec, vaccine coverage in young children are sub-optimal, mostly due to ambivalence toward vaccine safety and efficacy. We previously conducted a regional study in the Québec’s Eastern Townships region, the PromoVac Study, to test a new educational intervention, based on motivational interviewing techniques, aimed at promoting infant vaccination. This first study evidenced that the intervention led to a marked increase in mothers’ intention to vaccinate, and vaccine coverage in their infants. The current study protocol aims at scaling up these results at a provincial level using a randomized controlled trial design.

Methods

This pragmatic, randomized, controlled, parallel-group clinical trial will compare the effectiveness of the motivational interviewing to an educational intervention, including the distribution of an information flyer as standard of care on vaccination coverage in four maternity wards across the Province of Québec (PromovaQ). Adult mothers of children born in participating maternity wards were recruited between March 2014 and February 2015. Vaccination coverage will be assessed at 3-years of age, thus the trial is expected to be completed in March 2019. Statistical analyses will be conducted under the intention-to-treat principle. Vaccine coverage will be analyzed using Chi-squared distribution testing and logistic regression to identify determinant factors. Secondary outcomes will include vaccine hesitation and intention scores, mother’s knowledge, attitudes and beliefs about immunization, and psychosocial determinants of intention to vaccinate.

Discussion

In the case results of this Provincial RCT be confirmed, serious consideration should then be given by Ministry of Health authorities to the possible implementation of MI-based strategies across provincial maternity wards. To ensure adequate input and secure implementation, study design and results will be reviewed with relevant stakeholders, including the children’s families, and provincial and regional decision-makers. Results will be adapted and shared with all stakeholders.

Trial registration

ClinicalTrials.gov NCT02666872 (Retrospectively registered as January 28, 2016).

Current perspectives in assessing humoral immunity after measles vaccination

INTRODUCTION

Repeated measles outbreaks in countries with relatively high vaccine coverage are mainly due to failure to vaccinate and importation; however, cases in immunized individuals exist raising questions about suboptimal measles vaccine-induced humoral immunity and/or waning immunity in a low measles-exposure environment.

AREAS COVERED

The plaque reduction neutralization measurement of functional measles-specific antibodies correlates with protection is the gold standard in measles serology, but it does not assess cellular-immune or other parameters that may be associated with durable and/or protective immunity after vaccination. Additional correlates of protection and long-term immunity and new determinants/signatures of vaccine responsiveness such as specific CD46 and IFI44L genetic variants associated with neutralizing antibody titers after measles vaccination are under investigation. Current and future systems biology studies, coupled with new technology/assays and analytical approaches, will lead to an increasingly sophisticated understanding of measles vaccine-induced humoral immunity and will identify 'signatures' of protective and durable immune responses.

EXPERT OPINION

This will translate into the development of highly predictive assays of measles vaccine efficacy, effectiveness, and durability for prospective identification of potential low/non-responders and susceptible individuals who require additional vaccine doses. Such new advances may drive insights into the development of new/improved vaccine formulations and delivery systems.

Assessment of vaccine effectiveness during measles outbreak in the Federation of Bosnia and Herzegovina, 2014-2015

OBJECTIVE

Between February 2014 and September 2015 a large measles outbreak (5,084 cases) occurred in the Federation of Bosnia and Herzegovina (FB&H). The aim of this study is to assess the effectiveness of routine measles vaccination in the FB&H.

METHODS

We conducted an analysis of the resurgence period surveillance data and a retrospective cohort study involving primary school aged children in randomly selected schools.

RESULTS

Measles cases occurred among all age groups, mostly among the unvaccinated. Among fully immunized, 2.1% contracted measles. Measles vaccine effectiveness was high. The study indicates that one dose reduced the risk for measles by 91.9% (95% CI: 81.4-96.4%), two doses reduced the risk by 97.3% (95% CI: 95.5-98.4%). No evidence of waning immunity was found. Our survey reveals that a significant number of children had no immunization status registered.

CONCLUSIONS

The results of this study suggest that the resurgence was likely caused by an accumulation of measles-susceptible children not being vaccinated. This vaccine effectiveness study does not support possible vaccination failure as a contributing factor.

Stochastic two-group models with transmission dependent on host infectivity or susceptibility

Stochastic epidemic models with two groups are formulated and applied to emerging and re-emerging infectious diseases. In recent emerging diseases, disease spread has been attributed to superspreaders, highly infectious individuals that infect a large number of susceptible individuals. In some re-emerging infectious diseases, disease spread is attributed to waning immunity in susceptible hosts. We apply a continuous-time Markov chain (CTMC) model to study disease emergence or re-emergence from different groups, where the transmission rates depend on either the infectious host or the susceptible host. Multitype branching processes approximate the dynamics of the CTMC model near the disease-free equilibrium and are used to estimate the probability of a minor or a major epidemic. It is shown that the probability of a major epidemic is greater if initiated by an individual from the superspreader group or by an individual from the highly susceptible group. The models are applied to Severe Acute Respiratory Syndrome and measles.

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.

Factors contributing to measles transmission during an outbreak in Kamwenge District, Western Uganda, April to August 2015

Background

In April 2015, Kamwenge District, western Uganda reported a measles outbreak. We investigated the outbreak to identify potential exposures that facilitated measles transmission, assess vaccine effectiveness (VE) and vaccination coverage (VC), and recommend prevention and control measures.

Methods

For this investigation, a probable case was defined as onset of fever and generalized maculopapular rash, plus ≥1 of the following symptoms: Coryza, conjunctivitis, or cough. A confirmed case was defined as a probable case plus identification of measles-specific IgM in serum. For case-finding, we reviewed patients’ medical records and conducted in-home patient examination. In a case-control study, we compared exposures of case-patients and controls matched by age and village of residence. For children aged 9 m-5y, we estimated VC using the percent of children among the controls who had been vaccinated against measles, and calculated VE using the formula, VE = 1 - OR_M-H, where OR_M-H was the Mantel-Haenszel odds ratio associated with having a measles vaccination history.

Results

We identified 213 probable cases with onset between April and August, 2015. Of 23 blood specimens collected, 78% were positive for measles-specific IgM. Measles attack rate was highest in the youngest age-group, 0-5y (13/10,000), and decreased as age increased. The epidemic curve indicated sustained propagation in the community. Of the 50 case-patients and 200 controls, 42% of case-patients and 12% of controls visited health centers during their likely exposure period (OR_M-H = 6.1; 95% CI = 2.7–14). Among children aged 9 m-5y, VE was estimated at 70% (95% CI: 24–88%), and VC at 75% (95% CI: 67–83%). Excessive crowding was observed at all health centers; no patient triage-system existed.

Conclusions

The spread of measles during this outbreak was facilitated by patient mixing at crowded health centers, suboptimal VE and inadequate VC. We recommended emergency immunization campaign targeting children <5y in the affected sub-counties, as well as triaging and isolation of febrile or rash patients visiting health centers.

Measles

Measles is a highly contagious disease that results from infection with measles virus and is still responsible for more than 100 000 deaths every year, down from more than 2 million deaths annually before the introduction and widespread use of measles vaccine. Measles virus is transmitted by the respiratory route and illness begins with fever, cough, coryza, and conjunctivitis followed by a characteristic rash. Complications of measles affect most organ systems, with pneumonia accounting for most measles-associated morbidity and mortality. The management of patients with measles includes provision of vitamin A. Measles is best prevented through vaccination, and the major reductions in measles incidence and mortality have renewed interest in regional elimination and global eradication. However, urgent efforts are needed to increase stagnating global coverage with two doses of measles vaccine through advocacy, education, and the strengthening of routine immunisation systems. Use of combined measles-rubella vaccines provides an opportunity to eliminate rubella and congenital rubella syndrome. Ongoing research efforts, including the development of point-of-care diagnostics and microneedle patches, will facilitate progress towards measles elimination and eradication.

Identify the susceptibility profile to measles in the general population: Serological survey of measles antibodies in Shaanxi province, China, in 2016

The reported coverage with two doses of the measles vaccine (MCV) in Shaanxi Province, China, is greater than 95%, but the measles incidence over the whole province remains high. Cross-sectional serological surveys of measles antibodies in Shaanxi Province were conducted in 2016 to assess the population's immunity. The measles IgG levels were measured in serum samples using ELISA. The geometric means concentration (GMC) levels and seroprevalence rates with 95% CIs were calculated by region, gender, and age. A total of 3574 serum samples were collected from participants aged from 2 months to 49 years. The GMC of measles antibodies was 471.3 mIU/ml (95% CI: 445.9-498.2 mIU/ml), and the seroprevalence was only 85.9% (95% CI: 84.8-87.1%). A significant difference in the GMC (P < .05) but not the seroprevalence (P > .05) was observed among the 3 regions. The report measles incidences were high in individuals aged 0-7 months (33.2/100 000) and 8-17 months (26.8/100 000). Although both measles immunity (90.7%) and MCV coverage (89.7%) were low in children aged 8-17 months, the measles seroprevalence in adults was high at greater than 90%. These results revealed that further actions may be taken to increase vaccination coverage in children aged 8 months to 5 years over the whole province and teenagers in the south region. In particular, timely administration of the first MCV dose should be emphasized to prevent measles epidemics in children aged 8-17 months. Vaccination strategies may be varied by age and region.

Biophysical Properties and Antiviral Activities of Measles Fusion Protein Derived Peptide Conjugated with 25-Hydroxycholesterol

Measles virus (MV) infection is re-emerging, despite the availability of an effective vaccine. The mechanism of MV entry into a target cell relies on coordinated action between the MV hemagglutinin (H) receptor binding protein and the fusion envelope glycoprotein (F) which mediates fusion between the viral and cell membranes. Peptides derived from the C-terminal heptad repeat (HRC) of F can interfere with this process, blocking MV infection. As previously described, biophysical properties of HRC-derived peptides modulate their antiviral potency. In this work, we characterized a MV peptide fusion inhibitor conjugated to 25-hydroxycholesterol (25HC), a cholesterol derivative with intrinsic antiviral activity, and evaluated its interaction with membrane model systems and human blood cells. The peptide (MV.

Prevalence of risk factors for acquiring measles during the 2011 outbreak in Quebec and impact of the province-wide school-based vaccination campaign on population immunity

BACKGROUND

A large measles outbreak occurred in Quebec, Canada, in 2011. Although nearly two-thirds of the cases occurred in only two health districts, a mass vaccination campaign targeting all Quebec elementary and high school students without valid two-dose history was undertaken to prevent future outbreaks. We compared rates of non-vaccination and age at first measles vaccine dose among students in the two most-affected districts and the rest of the province and estimated the improvement in overall student measles immunity due to the mass school-based vaccination campaign.

METHODS

Data were extracted from the provincial vaccination registry for students in kindergarten to grade 11 during the 2011/2012 school year. A telephone survey was conducted in three sub-groups: students whose first measles vaccine dose recorded in the vaccination registry was received during the 2011 school vaccination campaign; students with no dose recorded in the registry whose parents refused receipt during the school campaign; and students with no dose recorded in the registry and no information about parental consent/refusal during the school campaign.

RESULTS

Neither the prevalence of being non-vaccinated nor a younger age at first pediatric dose were higher in the two most-affected districts versus the rest of the province. The school campaign vaccinated nearly 8% of all students including 7% who previously received at least one dose. Before the outbreak, 3% of students were not vaccinated and one-third of these (1%/3%) were vaccinated during the campaign. The campaign likely increased the absolute school population immunity by just 1.7%.

CONCLUSION

The concentration of measles cases in the two most-affected health districts during the large Quebec outbreak is not explained by more students who were unvaccinated or who had received their first vaccine dose at a younger age. The vaccination campaign reached one-third of unvaccinated students and only marginally improved population immunity.

Reduced Antibody Response to Infant Measles Vaccination: Effects Based on Type and Timing of the First Vaccine Dose Persist After the Second Dose

Background

The effect of age at first dose on the immunogenicity of a 2-dose pediatric schedule of measles-mumps-rubella (MMR) or measles-mumps-rubella-varicella (MMRV) vaccine was assessed in children born to mostly vaccinated mothers.

Methods

Immunogenicity data among children given their first measles vaccine dose between 11 and 22 months of age were pooled from 5 randomized controlled trials conducted in Europe and the United States between 2004 and 2010. Measles antibody titers were measured by enzyme-linked immunosorbent assay before and after each dose; geometric mean concentrations (GMCs) and the proportion seronegative (GMC <150 mIU/mL) were derived by age at first dose.

Results

Among 5542 children given a first measles vaccine dose at 11, 12, 13-14, and 15-22 months of age, the proportion seronegative decreased from 8.5% to 3.2%, 2.4%, and 1.5%, respectively (P < .001), whereas GMCs increased with older age measles vaccine initiation (P < .001). MMRV induced higher GMCs than MMR (P < .001). First and second dose GMCs were highly correlated (Spearman coefficient = 0.8).

Conclusions

As previously noted among infants born to mothers with history of wild-type measles, antibody responses among children born to vaccinated mothers were reduced based on earlier administration of their first measles vaccine dose at ≤12 vs ≥15 months of age. Negative effects of earlier age at first measles vaccine dose persisted after the second dose. The measles elimination goal may require a careful balance between earlier infant protection and the risk of reduced antibody responses and secondary vaccine failure among successive birth cohorts systematically initiated to measles vaccination <15 months of age.

Effectiveness of Early Measles, Mumps, and Rubella Vaccination Among 6-14-Month-Old Infants During an Epidemic in the Netherlands: An Observational Cohort Study

Background

Routinely, the first measles, mumps, and rubella (MMR) vaccine dose is given at 14 months of age in the Netherlands. However, during a measles epidemic in 2013-2014, MMR vaccination was also offered to 6-14-month-olds in municipalities with <90% MMR vaccination coverage. We studied the effectiveness of the early MMR vaccination schedule.

Methods

Parents of all infants targeted for early MMR vaccination were asked to participate. When parent(s) suspected measles, their infant's saliva was tested for measles-specific antibodies. The vaccine effectiveness (VE) against laboratory-confirmed and self-reported measles was estimated using Cox regression, with VE calculated as 1 minus the hazard ratio.

Results

Three vaccinated and 10 unvaccinated laboratory-confirmed cases occurred over observation times of 106631 and 23769 days, respectively. The unadjusted VE against laboratory-confirmed measles was 94% (95% confidence interval [CI], 79%-98%). After adjustment for religion and sibling's vaccination status, the VE decreased to 71% (-72%-95%). For self-reported measles, the unadjusted and adjusted VE was 67% (40%-82%) and 43% (-12%-71%), respectively.

Conclusions

Infants vaccinated between 6 and 14 months of age had a lower risk of measles than unvaccinated infants. However, part of the effect was caused by herd immunity, since vaccinated infants were more likely to be surrounded by other vaccinated individuals.

In Vivo Efficacy of Measles Virus Fusion Protein-Derived Peptides Is Modulated by the Properties of Self-Assembly and Membrane Residence

Measles virus (MV) infection is undergoing resurgence and remains one of the leading causes of death among young children worldwide despite the availability of an effective measles vaccine. MV infects its target cells by coordinated action of the MV hemagglutinin (H) and fusion (F) envelope glycoproteins; upon receptor engagement by H, the prefusion F undergoes a structural transition, extending and inserting into the target cell membrane and then refolding into a postfusion structure that fuses the viral and cell membranes. By interfering with this structural transition of F, peptides derived from the heptad repeat (HR) regions of F can inhibit MV infection at the entry stage. In previous work, we have generated potent MV fusion inhibitors by dimerizing the F-derived peptides and conjugating them to cholesterol. We have shown that prophylactic intranasal administration of our lead fusion inhibitor efficiently protects from MV infection in vivo We show here that peptides tagged with lipophilic moieties self-assemble into nanoparticles until they reach the target cells, where they are integrated into cell membranes. The self-assembly feature enhances biodistribution and the half-life of the peptides, while integration into the target cell membrane increases fusion inhibitor potency. These factors together modulate in vivo efficacy. The results suggest a new framework for developing effective fusion inhibitory peptides.

IMPORTANCE

Measles virus (MV) infection causes an acute illness that may be associated with infection of the central nervous system (CNS) and severe neurological disease. No specific treatment is available. We have shown that fusion-inhibitory peptides delivered intranasally provide effective prophylaxis against MV infection. We show here that specific biophysical properties regulate the in vivo efficacy of MV F-derived peptides.

Waning immunity against mumps in vaccinated young adults, France 2013

In 2013, 15 clusters of mumps were notified in France; 72% (82/114) of the cases had been vaccinated twice with measles-mumps-rubella vaccine. To determine whether the risk of mumps increased with time since the last vaccination, we conducted a case-control study among clusters in universities and military barracks. A confirmed case had an inflammation of a salivary gland plus laboratory confirmation in 2013. A probable case presented with inflammation of a salivary gland in 2013 either lasting for > 2 days or with epidemiological link to a confirmed case. Controls had no mumps symptoms and attended the same university course, student party or military barracks. We collected clinical and vaccination data via web questionnaire and medical records. We calculated adjusted odds ratios (aOR) using logistic regression. 59% (50/85) of cases and 62% (199/321) of controls had been vaccinated twice. The odds of mumps increased for twice-vaccinated individuals by 10% for every year that had passed since the second dose (aOR 1.10; 95% confidence interval (CI): 1.02-1.19; p = 0.02). Mumps immunity waned with increasing time since vaccination. Our findings contributed to the French High Council of Public Health's decision to recommend a third MMR dose during outbreaks for individuals whose second dose dates > 10 years.

Exploring gaps in surveillance of a small measles outbreak in Toronto, Canada

In early 2015, an outbreak of 10 confirmed measles cases occurred in Toronto, Ontario. As part of the outbreak response, the Toronto Public Health staff conducted both traditional and supplementary case investigation activities. Despite this extensive effort, and unlike many previous measles outbreaks in Canada, neither the source case nor any confirmed epidemiologic links between cases were identified. The outbreak investigation brought to light potential gaps in the current measles surveillance and suggested approaches to future investigations: routine use of social media and other time-stamped resources to enhance case investigation; early and repeated targeted communication with primary care partners to improve case detection; and continued efforts to increase and maintain sufficient immunization coverage to interrupt transmission.

Eradication of measles: remaining challenges

Measles virus (MeV) is an aerosol-borne and one of the most contagious pathogenic viruses known. Almost every MeV infection becomes clinically manifest and can lead to serious and even fatal complications, especially under conditions of malnutrition in developing countries, where still 115,000 to 160,000 patients die from measles every year. There is no specific antiviral treatment. In addition, MeV infections cause long-lasting memory B and T cell impairment, predisposing people susceptible to opportunistic infections for years. A rare, but fatal long-term consequence of measles is subacute sclerosing panencephalitis. Fifteen years ago (2001), WHO has launched a programme to eliminate measles by a worldwide vaccination strategy. This is promising, because MeV is a human-specific morbillivirus (i.e. without relevant animal reservoir), safe and potent vaccine viruses are sufficiently produced since decades for common application, and millions of vaccine doses have been used globally without any indications of safety and efficacy issues. Though the prevalence of wild-type MeV infection has decreased by >90 % in Europe, measles is still not eliminated and has even re-emerged with recurrent outbreaks in developed countries, in which effective vaccination programmes had been installed for decades. Here, we discuss the crucial factors for a worldwide elimination of MeV: (1) efficacy of current vaccines, (2) the extremely high contagiosity of MeV demanding a >95 % vaccination rate based on two doses to avoid primary vaccine failure as well as the installation of catch-up vaccination programmes to fill immunity gaps and to achieve herd immunity, (3) the implications of sporadic cases of secondary vaccine failure, (4) organisation, acceptance and drawbacks of modern vaccination campaigns, (5) waning public attention to measles, but increasing concerns from vaccine-associated adverse reactions in societies with high socio-economic standards and (6) clinical, epidemiological and virological surveillance by the use of modern laboratory diagnostics and reporting systems. By consequent implementation of carefully designed epidemiologic and prophylactic measures, it should be possible to eradicate MeV globally out of mankind, as the closely related morbillivirus of rinderpest could be successfully eliminated out of the cattle on a global scale.

Measles antibodies in cord blood in Portugal: Possible consequences for the recommended age of vaccination

The optimum age to give the first dose of measles vaccine must balance the risks of disease and vaccine failure. Both are influenced by the levels of transplacentally acquired maternal antibodies. This study was conducted in the Obstetric service of Portuguese hospital, in 2012-2013. Mothers were recruited after informed consent. Measles IgG was measured in 206 cord sera, using a commercial immunoassay. Geometric mean concentrations (and 95% CI) were 1849mIU/ml (1196-2857) and 790mIU/ml (618-1008) in cord sera of newborns from unvaccinated and vaccinated mothers respectively. Maternal age and vaccination status were both associated with the concentration in cord sera, but maternal age was the major predictor. The likely explanation is the same already mentioned in other studies: as a vaccination program progresses, vaccination coverage increases as measles incidence decreases. That results newborns from younger vaccinated mothers having less measles antibodies while the older mothers are more likely to have been infected with the wild virus. As the proportion of vaccinated mothers increase, developed countries tend to anticipate the recommended age of the first dose to 12 months of age. Models using hypothetical measles antibody decay rates in infancy were explored. Anticipating the first dose of MMR1 in Portugal to the age of 12 months might have not been the best decision but results were not conclusive, and arguments supporting or not the anticipation were discussed.

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

Background. A measles outbreak in Pohnpei State, Federated States of Micronesia in 2014 affected many persons who had received ≥1 dose of measles-containing vaccine (MCV). A mass vaccination campaign targeted persons aged 6 months to 49 years, regardless of prior vaccination.

Methods. We evaluated vaccine effectiveness (VE) of MCV by comparing secondary attack rates among vaccinated and unvaccinated contacts after household exposure to measles.

Results. Among 318 contacts, VE for precampaign MCV was 23.1% (95% confidence interval [CI], −425 to 87.3) for 1 dose, 63.4% (95% CI, −103 to 90.6) for 2 doses, and 95.9% (95% CI, 45.0 to 100) for 3 doses. Vaccine effectiveness was 78.7% (95% CI, 10.1 to 97.7) for campaign doses received ≥5 days before rash onset in the primary case and 50.4% (95% CI, −52.1 to 87.9) for doses received 4 days before to 3 days after rash onset in the primary case. Vaccine effectiveness for most recent doses received before 2010 ranged from 51% to 57%, but it increased to 84% for second doses received in 2010 or later.

Conclusions. Low VE was a major source of measles susceptibility in this outbreak; potential reasons include historical cold chain inadequacies or waning of immunity. Vaccine effectiveness of campaign doses supports rapid implementation of vaccination campaigns in outbreak settings.

Similar Antibody Levels in 3-Year-Old Children Vaccinated Against Measles, Mumps, and Rubella at the Age of 12 Months or 18 Months

BACKGROUND

Measles-mumps-rubella (MMR) vaccinations have been offered to Finnish children at 14-18 months and 6 years of age. In May 2011, the recommended age for the first vaccine dose was lowered to 12 months because of the European measles epidemic.

METHODS

Fingertip capillary blood samples were collected from 3-year-old Finnish children vaccinated once with MMR vaccine at 11-19 months of age. The immunoglobulin G (IgG) antibodies to all 3 MMR antigens were measured with enzyme-linked immunosorbent assay. Neutralizing antibodies and the avidity of antibodies were measured for measles virus.

RESULTS

From April through October 2013, 187 children were enrolled. Equally high proportions of the samples were seropositive for measles virus, mumps virus, or rubella virus antibodies, and there were no significant differences in the IgG antibody concentrations in children vaccinated at 11-13 months of age, compared with those vaccinated at 17-19 months of age. However, among children vaccinated at 11-13 months of age, boys had lower antibody concentrations than girls. Neutralizing measles virus antibody titers were above the threshold for protective immunity in all 78 samples analyzed. The measles virus antibody avidity indexes were high for all children.

CONCLUSIONS

MMR induces similar antibody responses in 12-month-old children as compared to 18-month-old children, but in boys increasing age appears to improve the antibody responses.

Measles Virus Neutralizing Antibody Response, Cell-Mediated Immunity, and Immunoglobulin G Antibody Avidity Before and After Receipt of a Third Dose of Measles, Mumps, and Rubella Vaccine in Young Adults

BACKGROUND

Two doses of measles, mumps, and rubella (MMR) vaccine are 97% effective against measles, but waning antibody immunity to measles and failure of the 2-dose vaccine occur. We administered a third MMR dose (MMR3) to young adults and assessed immunogenicity over 1 year.

METHODS

Measles virus (MeV) neutralizing antibody concentrations, cell-mediated immunity (CMI), and immunoglobulin G (IgG) antibody avidity were assessed at baseline and 1 month and 1 year after MMR3 receipt.

RESULTS

Of 662 subjects at baseline, 1 (0.2%) was seronegative for MeV-neutralizing antibodies (level, <8 mIU/mL), and 23 (3.5%) had low antibody levels (8-120 mIU/mL). One month after MMR3 receipt, 1 subject (0.2%) was seronegative, and 6 (0.9%) had low neutralizing antibodies, with only 21 of 662 (3.2%) showing a ≥ 4-fold rise in neutralizing antibodies. One year after MMR3 receipt, no subject was seronegative, and 10 of 617 (1.6%) had low neutralizing antibody levels. CMI analyses showed low levels of spot-forming cells after stimulation, suggesting the presence of T-cell memory, but the response was minimal after MMR3 receipt. MeV IgG avidity did not correlate with findings of neutralization analyses.

CONCLUSIONS

Most subjects were seropositive before MMR3 receipt, and very few had a secondary immune response after MMR3 receipt. Similarly, CMI and avidity analyses showed minimal qualitative improvements in immune response after MMR3 receipt. We did not find compelling data to support a routine third dose of MMR vaccine.

Variability in Humoral Immunity to Measles Vaccine: New Developments

Despite the existence of an effective measles vaccine, resurgence in measles cases in the USA and across Europe has occurred, including in individuals vaccinated with two doses of the vaccine. Host genetic factors result in inter-individual variation in measles vaccine-induced antibodies, and play a role in vaccine failure. Studies have identified HLA (human leukocyte antigen) and non-HLA genetic influences that individually or jointly contribute to the observed variability in the humoral response to vaccination among healthy individuals. In this exciting era, new high-dimensional approaches and techniques including vaccinomics, systems biology, GWAS, epitope prediction and sophisticated bioinformatics/statistical algorithms provide powerful tools to investigate immune response mechanisms to the measles vaccine. These might predict, on an individual basis, outcomes of acquired immunity post measles vaccination.

Text message reminders for timely routine MMR vaccination: A randomized controlled trial

OBJECTIVE

Measles-mumps-rubella (MMR) vaccination is important for preventing disease outbreaks, yet pockets of under-vaccination persist. Text message reminders have been employed successfully for other pediatric vaccines, but studies examining their use for MMR vaccination are limited. This study assessed the impact of text message reminders on timely MMR vaccination.

STUDY DESIGN

Parents (n=2054) of 9.5-10.5-month-old children from four urban academically-affiliated pediatric clinics were randomized to scheduling plus appointment text message reminders, appointment text message reminder-only, or usual care. The former included up to three text reminders to schedule the one-year preventive care visit. Both text messaging arms included a text reminder sent 2 days before that visit. Outcomes included appointment scheduling, appointment attendance, and MMR vaccination by age 13 months, the standard of care at study sites.

RESULTS

Children of parents in the scheduling plus appointment text message reminders arm were more likely to have a scheduled one-year visit than those in the other arms (71.9% vs. 67.4%, relative risk ratio (RRR) 1.07 [95% CI 1.005-1.13]), particularly if no appointment was scheduled before randomization (i.e., no baseline appointment) (62.1% vs. 54.7%, RRR 1.14 [95% CI 1.04-1.24]). One-year visit attendance and timely MMR vaccination were similar between arms. However, among children without a baseline appointment, those with parents in the scheduling plus appointment text message reminders arm were more likely to undergo timely MMR vaccination (61.1% vs. 55.1%, RRR 1.11 [95% CI 1.01-1.21]).

CONCLUSION

Text message reminders improved timely MMR vaccination of high-risk children without a baseline one-year visit.

The Reemergence of Measles

Measles, or rubeola, is a highly infectious, acute viral illness of childhood that is considered eliminated in the USA but has reemerged in the past few years. Globally, an estimated 20 million cases of measles continue to occur, and it remains a leading cause of death among young children. It is rare in the USA and other first world countries, but numerous outbreaks have occurred in the USA recently, due to a combination of factors including poor vaccine coverage and importation of cases among travelers returning from endemic areas. The diagnosis of measles is usually made clinically, when an individual presents with a constellation of symptoms including cough, coryza, conjunctivitis, high fever, and an erythematous maculopapular rash in a cephalocaudal distribution. Complications are common and include otitis media, pneumonia, encephalitis, and rarely death. A measles vaccine is available in two doses and provides excellent protection against the disease. Despite this, vaccination coverage, especially among young adults, remains poor. Given its resurgence in the USA and other countries, interventions are urgently needed to address low vaccination rates and vaccine hesitancy. Measles awareness should also be a priority among young clinicians, who may have never seen a case or are not familiar with the disease.