Measles has returned with worldwide revenge in recent years, ending sharp declines in cases observed since the turn of the new century.
Between 2000 and 2016, cases of measles recorded worldwide fell from 853,479 to 132,490. Cases started to rise again after that (SN: 30/11/18). In 2019, 869,770 people had measles, most since 1996, according to a study by the World Health Organization and the U.S. Centers for Disease Control and Prevention published online on Nov. 12 in the Weekly Morbidity Report and mortality.
Worldwide, the estimated number of deaths from measles in 2019 was 207,500, almost close to 50 percent since 2016.
“This is a very important setback and a tragic setback, because we have had a safe and effective measles vaccine since the early 1960s,” says William Moss, an infectious disease epidemiologist at the Johns Hopkins Bloomberg School of Public Health who did not participate. in the report. "We're making tremendous progress."
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The measles vaccine is a superstar in public health, with two recommended doses of around 97 percent effective in preventing the disease and a dose of around 93 percent effective. To stop outbreaks, about 95 percent of a community needs to be vaccinated (SN: 15/04/19).
In general, measles is infecting more people due to stagnant progress in increasing immunization coverage, says co-author Natasha Crowcroft, WHO's main advisor for measles and rubella control in Geneva. Globally, the estimated coverage with the first dose of measles vaccine has gone from 72 to 84 percent from 2000 to 2010, but has since stabilized at around 84 to 85 percent.
This “is high enough to slow the measles or interrupt it for periods of time, but it inevitably leads to the buildup of susceptible children, and eventually this explodes into outbreaks,” Crowcroft says. In 2019, 19.8 million babies did not receive the first dose of measles vaccine. Reasons for low coverage vary by region, but primary health care systems and weak access are the main factors, she says.
Major outbreaks in nine countries – Central African Republic, Congo, Georgia, Kazakhstan, Madagascar, Northern Macedonia, Samoa, Tonga and Ukraine – were responsible for 73 percent of reported cases in 2019. The study highlights issues that affected some of these nations. . Congo and Madagascar have many children vulnerable to measles because of very low vaccination coverage (SN: 24/04/19). More people in Samoa have moved away from the measles vaccine after two babies died due to a medical mistake made when they were immunized in 2018. In Ukraine, the lack of confidence in vaccines by health workers is one of the reasons for vaccination there 21/05/19).
The WHO groups the world into six regions; they all struggled with the measles. The Americas recorded 19,244 cases of measles in 2019, with major outbreaks in Brazil and the United States, which last year almost lost the claim to eliminate measles (SN: 16/12/19). There were 618,595 people who had measles in the African region in 2019 and 105,755 in the European region.
In 2020, the COVID-19 pandemic may add to future challenges in the measles reign. “Given all the problems that led to 2019, we’re not starting from a strong base,” Crowcroft says. Interruptions in immunization programs can result in more gaps in measles immunity, increasing the risk of outbreaks. The economic hardship caused by the pandemic has also increased malnutrition, making the disease worse; vitamin A deficiency in particular is associated with severe measles. "These problems tend to cluster in the same communities, aggravating the overall effect and increasing inequality."
Increasing the number of children receiving the two recommended doses of measles vaccine and implementing recovery vaccination for those who miss shots are some of the actions needed to regain control of measles, write Crowcroft and co-authors. “It takes a lot of careful work and multi-level support in a country to create a strong immunization program,” he says.
Finally, it may be possible to expand vaccination worldwide with the help of a vaccine patch (SN: 28/06/17). Single-dose patches have a series of small “needles” that are filled or coated with the vaccine; in some cases, the needles dissolve in the skin. Animal studies have found that patches are effective as a device for administering measles vaccines. Patches do not have the same cold temperature requirements for storage as the syringe-based measles vaccine, Moss says, and adhesive patches can be administered with minimal training.
“There are still several years to go,” he says. But being able to patch a child and immunize them "is going to be maybe transformative and will really help us increase measles vaccine coverage."