The recent measles outbreak in India and the US is a reminder that measles vaccination coverage is important. While most countries have measles vaccination programs, subnational coverage disparities are still prevalent in the US and India. In order to better understand these differences, we must analyze global and subnational estimates of measles vaccination coverage and develop statistical models to address these issues.
Abstract
Measles is an extremely contagious viral disease that can spread quickly from one community to another. It causes severe diarrhea, ear infections, and eye infections. In addition, it can be fatal for young children and infants.
The World Health Organization (WHO) and the CDC urge partners to work together to combat this highly contagious virus. Vaccination and surveillance are essential components of measles eradication efforts. These measures have reduced morbidity and deaths from measles. Yet, despite these successes, measles continues to remain a leading cause of illness and death in children.
To achieve high population immunity against measles, coverage of the first and second dose of MCV vaccine must be at least 95 percent. However, achieving this target is challenging for many nations.
The Global Vaccine Action Plan (GVAP), which aims to eliminate measles in five WHO regions by 2020, relies on estimates of global measles vaccination coverage to monitor progress toward the goals. Using this data to identify geographical areas with low immunity and vulnerable populations is key to advancing the GVAP.
A new study provides a detailed analysis of measles vaccination coverage in 72 countries with the highest MCV1 coverage. Despite large improvements over the past decade, the data show important subnational heterogeneities in vaccine coverage.
This is especially true in countries with low incomes. Countries with poor infrastructure and inadequate immunization services are particularly at risk of measles outbreaks. Boosting routine immunization in LMICs can mitigate the risk of measles outbreaks.
Low coverage of measles vaccines is also contributing to the continued prevalence of measles, which remains one of the leading causes of childhood morbidity and mortality worldwide. In fact, a third of all child deaths are preventable through vaccination.
Globally comparable estimates of measles vaccination coverage
Measles is a disease that is highly contagious and carries high morbidity. It is particularly dangerous for young children, particularly in resource-poor countries. In high-income regions, it causes death in about one in 5000 cases. The global measles epidemic appears to be on the decline in the 1990s and early 2000s but has seen a resurgence in recent years. Vaccination is almost entirely effective at preventing measles.
The World Health Organization (WHO) estimates that the rate of measles vaccination coverage in the world has remained at around 85% for nearly a decade. However, this is a far cry from the target of a measles-free society. A measles-containing vaccine (MCV) containing two doses is needed to achieve herd immunity, which enables a person to be protected from the disease. Currently, 71 percent of children are receiving their second MCV dose.
Despite the global measles vaccination coverage rate plateauing, progress toward the goal of measles eradication has been slow. In some countries, vaccination coverage has decreased due to disruptions in immunization services.
However, there have been improvements in surveillance systems that can prevent further transmission of the virus. Furthermore, better access to healthcare has been achieved. There is an increasing risk of measles outbreaks in certain areas, which could be prevented by improving surveillance and reducing vaccination hesitancy.
Despite these positive developments, progress toward global measles eradication appears to have stalled in the 2020s. Global measles vaccine coverage rates decreased by 2% in the year ahead. An estimated 22 million children did not receive their first dose of the measles-containing vaccine in 2020. This represents the largest increase in unvaccinated children in more than two decades.
Prepandemic and post-pandemic outbreaks of measles in the US
A report published last week by the World Health Organization (WHO) looks at the latest surveillance and immunization trends. During the past year, the largest measles outbreaks have occurred in Somalia, Yemen and Nigeria. These outbreaks could signal the beginning of larger measles outbreaks globally.
Researchers have found that the number of vaccines given to children worldwide has fallen below pre-pandemic levels. This decline is worrying. Depending on the vaccine, it can drop by 6-18%. Vaccines for Children is the federally funded VFC program that pays for vaccines for half of U.S. children.
Vaccine coverage was lowest among children on Medicaid. It was also significantly lower for Black children. Among other races/ethnic groups, the coverage was not as high.
Across the country, vaccination rates have dropped. As a result, many communities have failed to meet the herd immunity threshold. Measles is a highly contagious disease. Despite this, people are inured to the toll that it takes on people. Having low vaccination rates makes it easy for measles and other diseases to spread.
The perfect storm of factors contributes to an increased risk of large outbreaks. This includes inequities in access to vaccines, disruptions in surveillance, and increased diversion of testing and surveillance resources. In addition, it is easy for viruses to spread when vaccination rates dip below the herd immunity threshold.
The CDC is urging parents to get their kids caught up on vaccinations. They have created a social media toolkit that provides graphics and sample posts to help people explain the importance of routine childhood vaccinations.
If you are worried about a child’s immunizations, you may want to contact your health care provider. Your pediatrician is your best ally.
Prepandemic and post-pandemic measles vaccinations in India
Routine childhood immunization is a cost effective health intervention that protects children from vaccine-preventable diseases. Yet many countries are still struggling with low vaccination rates. In particular, middle-income countries account for a growing share of unprotected children. However, there is more to the problem than ideological rejection of vaccines.
Delays in child vaccinations have negative effects on health and economic outcomes in the short term and over the long term. Studies conducted in India and other parts of the world suggest that delayed vaccination has a disproportionate effect on vulnerable populations.
Researchers found that delayed vaccination had a greater impact on the health of vulnerable children in rural areas. Children living in the least deprived regions were more likely to receive a timely MMR vaccination. However, this was not the case for children from mixed ethnic backgrounds or those missing an ethnic background.
In addition to the immediate negative impacts of missed vaccinations on preventable morbidity and mortality, the delay in vaccination increases the burden of other vaccine-preventable diseases. This increased vaccine morbidity and mortality is a societal health concern that requires attention.
A national family health survey-4 (NFHS-4) investigated delayed vaccination in India. It included a cohort of 33 226 pre-pandemic and 32 446 pandemic children from diverse demographic and geographic regions. The results showed that children born in India after the COVID-19 outbreak had lower rates of timely vaccination than those born in India before the pandemic. Compared with children from non-ethnic groups, children from white and mixed ethnic backgrounds had the lowest rate of timely MMR vaccination.
These findings demonstrate the need for future policy and public health interventions to address issues such as deprivation, ethnicity, and the availability of routine health services during an infectious disease outbreak. They also support prioritizing quality improvement and catch-up campaigns, particularly in lower-income countries.
Subnational coverage disparities in measles vaccination coverage
Measles is a highly contagious disease, which can lead to high fever and rash. Vaccine coverage is essential for preventing outbreaks and reducing the morbidity and mortality associated with the disease. Despite strong global vaccination initiatives, the coverage disparities between high-income countries and low-income countries remain high. Identifying geographic areas where these disparities are most acute is critical for tracking progress towards Global Vaccine Action Plan (GVAP) targets.
There have been studies of subnational coverage disparities in measles vaccination, but these have only been performed in select years. The aim of this study is to provide an understanding of the magnitude of subnational geographical disparities in measles vaccination, and their contribution to measles transmission. It also provides a basis for advocates to make specific, evidence-based coverage decisions.
In addition to identifying geographic locations where subnational disparities are most prevalent, estimates of geographical inequality are also useful for assessing the progress countries have made toward achieving global targets. Countries have improved their MCV1 coverage in recent years, but large disparities remain. However, these differences are not evenly distributed across the population, which may be a contributor to ongoing disease transmission.
A second step Bayesian geostatistical modeling framework was used to model vaccine coverage as counts in binomial space. It leveraged covariate relationships and generalized linear regression with spatial and temporal terms.
The results of this study highlight important differences in the level of coverage between urban and rural locations. Although coverage levels are relatively high in urban areas, the rate of coverage among unvaccinated children is much lower in remote rural locations.
Although the estimates of geographical inequality used in this study are not the only sources for evaluating trends in this area, they may be the best resource for identifying differential vaccination status by geographical location. They provide a means for assessing the impact of policy initiatives and for determining the most effective means to address vaccination disparities.