Implementation of a national measles elimination program in Iran: Phylogenetic analysis of measles virus strains isolated during 2010-2012 outbreaks

Assessing seropositivity of MMR antibodies in individuals aged 2-22: evaluating routine vaccination effectiveness after the 2003 mass campaign-a study from Iran's National Measles Laboratory

BACKGROUND AND PURPOSE

The seroprevalence of antibodies against measles, mumps, and rubella (MMR) was evaluated 17 years following a mass vaccination campaign in individuals aged 2 to 22 years who had received routine immunization but were not eligible for an extended immunization program.

METHODS

Samples were acquired from Iran's National Measles Laboratory (NML), with individuals showing positive IgM results excluded. Out of the samples collected in 2020, a random selection of 290 serum samples was chosen, representing individuals between the ages of 2 and 22 years from diverse regions in the country. These samples were subjected to analysis using an enzyme-linked immunosorbent assay (ELISA) to quantify specific IgG antibodies against MMR.

RESULTS

The seroprevalence rates of antibodies for measles, mumps, and rubella were determined to be 76.2%, 89.3%, and 76.9%, respectively. Younger age groups exhibited higher seropositivity rates for measles and mumps, whereas the 7- to 11-year-old group demonstrated the highest seropositivity rate for rubella. A reduction in antibody status was observed from younger to older age groups, particularly those aged 17-22.

CONCLUSION

The study unveiled suboptimal antibody levels for measles and rubella, highlighting the necessity for further investigation and potential adjustments to future vaccination strategies. Moreover, the decline in antibody status post-vaccination can accumulate in seronegative individuals over time, elevating the risk of outbreaks.

Epidemiology of measles in southern Iran: trends, challenges, and vaccination insights

Background

Measles, a highly contagious and vaccine-preventable disease, continues to present global public health challenges. This retrospective study focused on measles outbreaks in Hormozgan province, southern Iran, spanning from 2014 to 2019.

Methods

Between 2014 and 2019, patients suspected of having measles, as reported by medical centers in Hormozgan, were subject to a comprehensive evaluation. The diagnosis of measles was conclusively established through the use of real-time polymerase chain reaction (RT-PCR) testing. A detailed collection of pertinent data was undertaken. SPSS software, version 21, was employed for statistical analysis.

Results

In the current study, out of 1291 clinically suspected measles cases, 151 were PCR-confirmed, with an average age of 16.77 years (±10.46), comprising 50.9% males and 49.1% females. The annual distribution showed varied incidence: 8.4% in 2014, peaking at 18.8% in 2015, then fluctuating to 11.4% in 2016, 0.8% in 2017, and 17.9% in 2018, with no cases in 2019. Among confirmed cases, 16.5% were vaccinated, while 68.2% were not, and 15.23% had unknown vaccination status.

Conclusion

This retrospective study highlights the ongoing challenge of measles in Hormozgan province, Iran, from 2014 to 2019. Despite measles being preventable by vaccination, a significant number of cases were confirmed among both vaccinated and unvaccinated individuals, indicating gaps in immunization coverage and effectiveness. The fluctuating annual incidence, with a peak in 2015 and no cases in 2019, suggests variable success in disease control efforts. This underscores the need for enhanced surveillance, improved vaccination strategies, and public health interventions to effectively combat measles outbreaks in this region.

Genetic Characterization of the H Gene of MeV Strains (H1, B3, and D4) Recently Circulated in Iran for Improving the Molecular Measles Surveillance in the National Measles Lab

Background

Despite decreasing the global burden of measles disease after the introduction of vaccination, measles remains one of the most devastating childhood diseases. Since genotype B3 is reported as a predominant Measles Virus (MeV) genotype recently, the current study aimed to better understand MeV genetic variation by analyzing the complete sequence of Hemagglutinin (H) gene associated with outbreaks of circulated genotypes in Iran.

Methods

Nine positive measles specimens were selected from three circulated different genotypes H1, B3, and D4. Two different regions of MeV RNA were detected by RT-PCR assay. Sequence data and phylogenetic trees were analyzed and constructed by MEGA X software program. Moreover, missense and silent mutations in critical positions of the MeV-H protein were investigated.

Results

The result of phylogenetic analysis from the C-terminus of the Nucleoprotein gene (NP-450) and the complete H gene revealed that the mean sequence diversity was 0.06%-0.08% and 0.04%, respectively. Genotype H1 had the highest mutation in this study; however, the substitutions in genotype B3 fundamentally occurred in critical epitopes. Moreover, genotype D4 was more stable than genotypes B3 and H1.

Conclusion

Mutations were investigated in the whole sequence of H protein. Moreover, the mutations that occur in the critical sites of the protein have an important effect on the pathogenicity of the virus. In this way, we were able to illustrate why genotype B3 is more transmissible than other measles genotypes and is the most important circulating genotype around the world.

Measles elimination successful and its relevant challenges in Iran

Measles is an infectious childhood disease with some death annually. The expansion of the coverage of vaccination plan has significantly reduced the mortality rate of this disease. Given that the endemic measles virus is not transmitted in the country and based on Regional Verification Commission (RVC) for Measles and Rubella Elimination has declared that measles and rubella have been eliminated in three countries of Eastern Mediterranean Region including Islamic Republic of Iran, Bahrain, and Oman. Therefore, to continue and preventing from reemerging of measles in Iran, it is essential to maintaining the immunization programs, diagnose, and investigate all suspicious cases and outbreaks. This article investigates the challenges facing to measles after elimination declaration in Iran. However, the elimination of these diseases to be sustainable needs a vigorous case identification protocol and contact follow up.

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.

Monitoring progress towards the elimination of measles in Iran: supporting evidence from 2014 to 2016 by application of measles outbreaks data

BACKGROUND

To achieve the goal of measles eradication, all WHO member countries should continuously monitor the status of measles elimination. This work aims to characterize measles outbreaks in Iran from 2014 to 2016 and calculate the effective reproduction number, given that the country has recently eliminated measles.

METHODS

Effective Reproduction Number (R) was estimated to achieve the goal of measles elimination using measles related outbreaks data and epidemiological data from the cases linked to imported cases. Three methods were used to estimate R includes (i) proportion of cases imported, (ii) distribution of outbreak size and (iii) distribution of outbreak generations.

RESULTS

Of the 153 outbreaks occurring during the three years of the study, 29 outbreaks (19%) were unknown source, 86% of them were single cases. Estimates of R during the study period by proportion of cases imported were 0.79 (95% CI: 0.73-0.86). Corresponding values for distribution of outbreak size and distribution of outbreak generations methods were R = 0.83 (95% CI: 0.68-0.97) and R = 0.76 (95% CI: 0.54-0.90), respectively.

CONCLUSIONS

Estimated values of R represent the important achievement that the outbreaks of measles originating from the indigenous genotype in Iran have been eliminated. Moreover, Iran has also achieved the goal of measles elimination by end of 2015.

Estimation of measles risk using the World Health Organization Measles Programmatic Risk Assessment Tool, Iran

Introduction

Based on the World Health Organization (WHO) reports the EMRO countries did not reached to eradication of measles at 2010. This study aimed to estimate the risk of measles outbreak in different districts of Iran to identify high-risk areas based on WHO measles programmatic risk assessment tool.

Materials and methods

The WHO measles programmatic risk assessment tool was used to estimate the overall risk of measles in 31 providences and 322 districts of Iran at 2017. The measles risk was calculated by a function of four indicator scores including population immunity, surveillance quality, program performance, and threat assessment and the overall risk of measles for each districts calculated. Then, the tool assigned each district a risk category of low, medium, high, or very high according to the overall risk score.

Results

Of the 322 districts in Iran, all districts were categorized as low risk and there was no very high risk, high risk and medium risk district in Iran. Twenty-six districts (7.4%) received to risk point higher than 20. Based on population immunity and program delivery performance indicators, all districts in Iarn were categorized as low risk and 92.86% of districts were in low risk category by surveillance quality indicator.

Conclusion

The overall risk of measles profile was categorized as low risk and Iranian practices for measles elimination is very good in comparing other studies in this area. However, more attempts should be conducted to sustaining the surveillance quality indicators in all districts.

Monitoring of Surveillance Quality Indicators of Measles in Iranian Districts: Analysis of Measles Surveillance System 2014-2016

BACKGROUND

The elimination target for measles as an acute and contagious disease in Eastern Mediterranean Region (EMR) and Iran is planned by high-quality surveillance. We aimed to monitor the surveillance quality indicators of measles by in all districts of Iran during 2014-16.

STUDY DESIGN

A cross-sectional study.

METHODS

Four quality surveillance indicators of measles including non measles discarded rate, percent of suspected cases with adequate investigation, percent of adequate blood specimen collection and percent with timely availability of laboratory results were assessed in Iran. Surveillance data of measles were extracted from the measles surveillance system and the risk point score for each district was calculated based on WHO Risk Assessment Tool by a function of four indicators.

RESULTS

Overall, 14312 suspected cases and 322 districts were assessed and the risk points of measles' quality surveillance showed that 92.8% of Iranian districts were categorized as low risk, 2.8% medium risk, 0.62% high risk and 3.73% very high-risk category. The appropriate non measles discarded rate indicator was 87.3%. The percent of suspected cases with adequate investigation (more than 2 per 100000 people) was 87.9%. Moreover, the average of percent adequate blood specimen collection and percent with timely availability of laboratory results was 85.16% and 85.71%, respectively in all Iranian districts.

CONCLUSIONS

The surveillance quality indicators in Iran were good and higher than the WHO plans. Increasing the percentage of non-measles discarded rate could improve the poor quality in high risk and very high-risk districts.

Poor quality data challenges conclusion and decision making: timely analysis of measles confirmed and suspected cases line list in Southern Nations Nationalities and People's Region, Ethiopia

BACKGROUND

Measles is one of the leading causes of death among young children even though a safe and cost-effective vaccine is available. Timely analysis of measles surveillance data is crucial for epidemic control and can show disease control program status. Therefore, this study aimed to show vaccination status and delay in seeking health care using surveillance data.

METHODS

A retrospective study was carried out in Southern Nations Nationalities and People's Region (SNNPR), Ethiopia. We reviewed 2132 records from measles surveillance line list data from July 2013 to January 2014. Descriptive statistics were performed using SPSS 20 for Windows.

RESULTS

From a total of 2132 confirmed and suspected measles cases, 1319 (61.9%), had at least one dose of measles containing vaccine; the rest 398 (18.7%) and 415 (19.5%) were unvaccinated and had unknown status respectively. About two fifth, 846 (39.7%), cases visited health facilities within 48 h of onset of clinical signs/symptoms with a median of 2.0 days, IQR (1.0, 3.0).

CONCLUSION

Majority of the measles cases were vaccinated with at least one dose of measles containing vaccine and vaccination data or vaccine potency at lower level was unclear. Delay in seeking healthcare was noted as only about two fifth of cases visited health facilities within 48 h of clinical manifestation. Vaccination and surveillance data quality and factors associated with delay in seeking health care should be investigated.

Documentation of Measles Elimination in Iran: Evidences from 2012 to 2014

Background: Documentation of achieving the goal of measles elimination to justify to international organizations including the WHO is a priority for public health authorities. This study aimed to address the status of Iran in the achievement of the measles elimination goal from 2012-2014.

Study Design: A descriptive study.

Methods: Data on the measles outbreaks were extracted from the national notifiable measles surveillance system in Iran from 2012 to 2014. The required documents regarding the achievement of measles elimination, including Effective Reproduction Number (R) and the distribution of outbreak size, was addressed. The R was calculated using the proportion of imported cases as 1 − P, where P is equal to the proportion of cases that were imported. The distribution of the measles outbreaks size was described using descriptive statistics to show their magnitudes. The proportion of large outbreaks with more than 10 cases was considered as a proxy of the R value.

Results: The total number of measles cases was 232 cases (including 186 outbreak related cases) in 2012 and 142 cases in 2014, including108 outbreak related cases. The distribution of the measles outbreak size of occurred outbreaks from that period indicated that there were 37 outbreaks with three or more than three cases. The R value in 2012 was 0.87 and the corresponding value for 2014 was 0.76.

Conclusions: According to the magnitude of effective reproduction number and distribution of outbreaks' size, measles has been eliminated in Iran. However, it is necessary to consider the potential endemic activity of measles because of no authorized immigration.

Comparison of neutralizing antibody titers against outbreak-associated measles genotypes (D4, H1 and B3) in Iran

Despite the accessibility of a promising vaccine, outbreaks of the measles virus (MV) take place even in well-vaccinated populations. D4, H1 and B3 genotypes have been detected regularly in different regions of Iran. These observations highlight the necessity of evaluating the protective efficacy of the vaccine against currently circulating MV genotypes during the elimination phase. A focus reduction neutralization test has been developed to measure the neutralizing antibodies against different genotypes of MV, such as H1, D4, B3 and vaccine strain (A), in children after second doses of measles vaccine. The geometric mean titer (GMT) rates of the sera against D4, H1, B3 and A genotypes were 95.9, 90.5, 32.0 and 76.1, respectively. Low GMTs of antibody against the B3 genotype compared with the other genotypes were indicated. Based on the current study results, the MV antibody titers in the sera of vaccinated cases are sufficient to neutralize all circulating genotypes in Iran; however, neutralizing antibody titers were lower for the B3 genotype than for the H1, D4 and A genotypes. The heterogeneous nature of MV, for instance the nucleotide sequence diversity between different strains, necessitates the evaluation of the protective efficacy of the vaccine against measles B3 genotype in countries where this virus has been the most commonly identified circulating genotype.

Towards measles elimination: Phylogenetic analysis of measles viruses in Turkey (2012-2013) and identification of genotype D8

Molecular characterization of different measles virus (MV) strains is essential to combat the disease. Sixty measles MV strains were obtained from throat swabs or urine of patients in Turkey between 2012 and 2013 and characterized. MV RNA sequences (n = 60) were analysed for 456 nucleotides representing hypervariable domain of the nucleoprotein (N) gene. Of the 60 strains analysed 53 were the D8 genotype, 6 were B3, 1 was D4, and 1 was A. This report describes MV genotype D8 that was involved in a measles outbreak in Turkey. Sequences of most genotype D8 strains (n = 51) were identical to the sequence of variant D8-Frankfurt-Main, which has been associated with outbreaks throughout Europe. Despite the lack of epidemiologic information, a phylogenetic analysis suggested that the genotype D8 MV may have been brought to Turkey from elsewhere. Phylogenetic and epidemiological findings suggested that strains identified in tourists and associated with importation included one strain of genotype D8, one strain of genotype B3, and one strain of genotype D4. These findings from the 2012 to 2013 outbreak in Turkey confirm that pockets of unimmunised individuals are making the country susceptible to measles outbreaks. To prevent further outbreaks, deliberate and sustained effort must be made to reach, and immunise susceptible age groups. Towards measles elimination process, continued molecular surveillance of measles strains in Turkey will help identify transmission patterns of virus and evaluate vaccination efforts. J. Med. Virol. 88:1867-1873, 2016. © 2016 Wiley Periodicals, Inc.

Endemic and imported measles virus-associated outbreaks among adults, Beijing, China, 2013

In 2013, a resurgence of measles occurred in Beijing, China. The outbreaks occurred among adults and were associated with endemic genotype H1 and imported genotype D8 viruses. Migrant workers were disproportionately represented in the outbreaks; thus, vaccinating such workers against measles may be an effective strategy toward the elimination of this disease.