The Ebola outbreak that infected more than 24,000 people and killed more than 10,000 could lead to thousands more measles deaths among children due to the disruption of health care systems in Guinea, Liberia and Sierra Leone, according to a new study.
With the Ebola crisis upending the normal childhood immunization programs, the number of unvaccinated children between the ages of 9 months and 5 years old in these countries could swell to 1,129,000, up from about 778,000, according to the study released Thursday in the journal Science.
That could equate to an extra 100,000 measles cases within 18 months and an additional 2,000 to 16,000 deaths in a worst case scenario, researchers predicted — potentially more than were killed by the Ebola virus itself.
Justin Lessler, a professor of infectious disease epidemiology at the Johns Hopkins Bloomberg School of Public Health in Baltimore and one of the authors of the paper, said in a call with reporters Wednesday that health care systems as a whole in Guinea, Liberia and Sierra Leone took a huge hit as a result of the Ebola crisis. Many health clinics were shuttered, and people stayed away from those that were open because of fears surrounding the virus.
“This prompted concern in the global health community about the effect that these disruptions might be having on vaccination for measles and other childhood infections,” he said. “Measles in particular is known to show up during or after humanitarian crises because it’s so infectious.”
Researchers from Princeton, Penn State, Johns Hopkins, the University of Southampton in the U.K. and the U.S.’s National Institutes of Health wanted to create a model for predicting how many people would be impacted by the increased risk of catching measles and how many people might die.
They used data on child vaccination rates from recent nationwide surveys to create a statistical projection of how the measles might spread, and determined that vaccination rates could decrease by as much as 75 percent. They statistically simulated the disruption of health care services caused by the Ebola outbreak, and found that they would lead to nearly 400,000 additional unvaccinated children across Guinea, Liberia and Sierra Leone.
Outbreaks of the measles, a respiratory disease marked by a cough, a runny nose and a rash, tend to follow humanitarian crises, because it is so contagious. For example, following years of war and instability the Democratic Republic of Congo, a measles outbreak infected nearly 300,000 people and killed over 5,000 between 2010 and 2013, according to the study.
Lessler said that Guinea, Liberia and Sierra Leone had been discussing mass vaccination campaigns that were delayed by the Ebola crisis. Previous, more localized vaccination campaigns have been successful at reducing the spread of measles in the region — plummeting down to just 6,937 reported cases in those three countries combined between 2004 and 2013, a drastic decline from 93,685 reported cases in those countries between 1994 to 2003. (The researchers emphasized that these were reported cases, so there could have been more.)
Still, measles vaccination rates in the region hover around 80 percent or less, according to UNICEF. And as the World Health Organization warned on Wednesday, dwindling numbers of new Ebola cases may cause the world to lose interest in the Ebola crisis, but it is too early to assume the worst is over and to stop the flow of financial support to the region. That warning came ahead of new figures showing the death toll from Ebola had hit 10,004 people.
Lessler said that “recent information” about vaccination rates post-Ebola suggested to the researchers that their estimate of vaccination rates as declining by 75 percent might be “a touch too pessimistic.” But, even if vaccination rates were to be stunted by a far more moderate 25 percent, the region could expect at least 10,000 more measles cases and between 500 and 4,000 more deaths, he said.
“Regardless what the exact number is, the solution is clear,” Lessler said. “Supplemental immunization campaigns have been successfully performed in all three countries in the past and could virtually eliminate Ebola’s effect on a measles risk in the region, likely making the situation better than it was before the Ebola crisis began.”