Measles is on the rise around the world: why…and why it’s a problem

We often tend to think of measles as an embarrassing childhood disease with those red spots that gradually cover the whole body but are harmless and overcome. Wrongly so: it is a serious viral disease that is very contagious (an infected person can infect 15 to 20 others; it is contagious on average before the rash and five days after) and easily transmissible. It can occur at any age and lead to serious complications – sometimes fatal.

That’s why we should be concerned that the number of measles cases reported worldwide rose by 556% between 2016 and 2019 to 869,770, the highest number since 1996. Over 140,000 people died from it in 2018, mostly children under the age of 5. A tragedy all the more disheartening because it could have largely been avoided.

Additionally, a measles outbreak in the Democratic Republic of the Congo between 2018 and 2020 infected more than 460,000 children and caused nearly 8,000 deaths.

The increase continues and the UN has already warned that measles cases will increase by 79% worldwide in the first two months of 2022. Between September 2021 and February 2022, Somalia reported 5,760 measles cases, Nigeria 5,613 cases, India 4,178 cases, Ethiopia 1,979 cases, Pakistan 1,861 cases, and so on. So you could go on enumerating the countries affected by thousands of infections. This is very bad news.

We thought it was eradicated…but it’s coming back

Some Western countries are also following this trend. In 2000, the United States of America declared measles eliminated from its territory. In 2019, however, nearly 1,300 measles cases were reported in 31 states across the country, the highest number since 1992. What’s going on?

Analysis of the 2018-2019 measles epidemic in New York, the country’s largest in nearly three decades, has identified the factors behind this unexpected magnitude: In this case, it was late vaccination of young children combined with increased contact between them…probably at “Measles parties” organized to deliberately infect children.

Infections have occurred mainly in young children aged 1 to 4 years and infants less than one year old. To contain the outbreak, the New York City Department of Health and Mental Health launched extensive vaccination campaigns and mandated mandatory vaccination for everyone living, working or attending school within the relevant codes.

As a result of this voluntary policy, more than 32,000 people under the age of 19 were vaccinated against measles, mumps and rubella (MMR) between October 2018 and July 2019. And the epidemic has receded.

Further analysis suggests that without the vaccination campaigns, the outbreak could have infected between 6,500 and 8,100 people, compared to the actual 649 cases.

Let’s be clear: these “measles parties” are a senseless and dangerous practice that needs to be eradicated.

The French don’t trust vaccines

Before the introduction of the measles vaccine in 1963 and the generalization of vaccination, major global epidemics occurred about every 2 to 3 years, causing about 2.6 million deaths annually. Between 2000 and 2018, vaccination prevented around 23.2 million deaths.

Despite the evidence, a global survey of 67 countries released in 2016 found that confidence in vaccine safety in France is the lowest in the world. And this increases the risk of infectious epidemics, including measles. Perhaps because of this problem, measles cases in France totaled 2,637 in 2019. (Between 2008 and 2020, of the more than 30,000 cases reported in France, 1,700 people developed severe pneumonia, 42 developed a neurological complication (39 encephalitis, 1 myelitis, 2 Guillain-Barré) and 26 died, d’s note. editor.)

Fortunately, according to 2020 data, confidence in the value and safety of the measles vaccine has increased significantly in many countries. In general, it is considered high in the European Union.

In Spain, confidence in vaccines is good. The MMR (measles, rubella and mumps) vaccination program was introduced in 1981. The MMR vaccine contains live attenuated measles and mumps viruses prepared in chick embryo cell culture. It also contains live attenuated rubella virus produced in human lung cells (specifically fibroblasts).

Due to its consistently high vaccination coverage, Spain was declared endemic measles transmission free in 2014. In 2017, the World Health Organization for Europe declared measles eliminated from the country after no endemic transmission had occurred for a period of at least 36 months. Since then, reported measles cases and outbreaks have always been imported or associated with imports.

The risk of complications is never negligible, even for infants who are particularly vulnerable. Phichet Chaiyabin/Shutterstock

Diversity of the measles virus

WHO recognizes 24 measles virus genotypes (A, B1, B2, B3, C1, C2, D1, D2, D3, D4, D5, D6, D7, D8, D9, D10, D11, E, F, G1, G2 , G3 , H1 and H2), divided into eight clades (AH). Despite this heterogeneity, all are considered to belong to a single main type. Most strains used in vaccine development are derived from the Edmonston strain (genotype A) isolated in 1954 and are effective against all others.

Currently, only three of these 24 known genotypes are responsible for epidemics worldwide: the H1 genotype endemic to China; B3, mainly present in African countries (where it originated); and the D8 genotype, which emerged in Asia in the 1980s but is now common worldwide.

The D8 and B3 genotypes are responsible for the epidemics that have occurred in Europe, Asia and North America in recent years.

The effects of the Covid-19 pandemic

Unfortunately, the actions taken to combat one epidemic can have detrimental consequences for another. Therefore, the Covid-19 pandemic is having a serious impact on immunization programs and measles surveillance systems in many countries.

In March 2020, the World Health Organization (WHO) released guidelines that mass vaccination campaigns should be suspended to maintain physical distancing and minimize transmission of the coronavirus.

However, the disruption of vaccination services, even for a short time, has meant that the number of vulnerable individuals and communities where coverage is less than 95% (the rate needed to achieve herd immunity to this virus) has increased gain). The result has been an increase in measles outbreaks worldwide.

It is estimated that a 15% reduction in routine measles vaccination could increase child mortality by almost 250,000 in the poorest countries. The suspension of these mass vaccination campaigns is particularly damaging in conflict-affected countries. Among other things, because then malnutrition of children and mothers occurs more frequently, which increases mortality in the event of infection.

A disease that is not harmless

Although vaccination and good medical care can reduce the likelihood of serious complications, measles-related deaths and hospitalizations from complications occur even in developed and industrialized European countries. (Complications occur in 30% of cases and are more serious in immunocompromised individuals, infants, and adults over the age of twenty. They range from otitis media and diarrhea to damage to the liver, kidneys, lungs or eyes. Neurological complications are observed in one in a thousand cases, encephalitis for example. editor.)

For this reason, the WHO recommends vaccination of susceptible children and adults for whom it is not contraindicated.

There is currently no doubt that the measles vaccine is safe, effective and inexpensive. It should therefore be included in all national vaccination programmes.The conversation


author

Raul Rivas GonzalezCatedrático de Microbiology, University of Salamanca


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This article was republished by The Conversation under a Creative Commons license. read thisoriginal article.

Declaration of Interest

Raúl Rivas González does not work for, consult with, own interest in, or receive funding from any organization that might benefit from this article, and has disclosed no affiliation other than his research organization.

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The Universidad de Salamanca contributes funds as a founding member of The Conversation ES.

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