Call it the latest Ebola complication.
The epidemic that already killed almost 10,000 people in west Africa also upended daily life and scuttled plans to vaccinate thousands of kids against preventable diseases. As a result, an additional 100,000 children may have been left vulnerable to measles, according to new projections. If those inoculation gaps are not addressed, measles could deliver a death toll rivaling the Ebola epidemic itself, warns a new study published today in Science.
There is no cure for either Ebola or measles—but in the case of the latter there is a proven vaccine that can prevent a person from contracting the disease in the first place. That is important because measles is far more contagious than Ebola. Although one Ebola patient is projected to infect one or two other people, one measles sufferer can infect an estimated 12 to 18 additional people (assuming no one is immune to the disease via vaccination or natural immunity). To make matters worse, unlike Ebola, someone with measles may be contagious without showing symptoms.
Vaccination gaps
Even before Ebola, the latest estimations for measles vaccination coverage in Sierra Leone, Guinea and Liberia painted a grim picture. Vaccination coverage numbers calculated by the World Health Organization (WHO) and United Nations Children’s Fund (UNICEF) for 2013 suggested that the number of kids who had received the first of two doses of the measles vaccine by age one hovered between 62 percent and 83 percent, depending on the country. (Guinea had the lowest vaccination coverage of the three.) But the Ebola outbreak probably exacerbated the problem by further depressing inoculation rates, according to the new research in Science. With such alarming vaccine gaps a large outbreak could conceivably tear through communities and cause as many as 16,000 deaths, the international research team wrote. Their analysis assumes that the Ebola outbreak festered for about 18 months in total and led to a 75 percent drop in vaccination rates.
Last year UNICEF sounded the alarm about this issue, noting that immunization efforts had stalled in some areas, thanks to Ebola. Large vaccine gaps are not uncommon following disasters. But Ebola presented a particularly rare threat because not only did it occur across a wide geographic region but it also engendered fear that often kept people from using available health care services. Moreover, efforts to tamp down Ebola often diverted resources from other medical needs and even led to the deaths of healthcare workers.
Inoculations against measles and other preventable diseases are typically administered by a mix of local health care workers and international aid organizations that consult with a government’s ministry of health and WHO. In these west African nations supplemental vaccination campaigns were rolled out every few years to help boost inoculation rates, and each of the three countries were planning such activities in 2014 or 2015, says lead author Justin Lessler, an infectious disease epidemiologist at Johns Hopkins Bloomberg School of Public Health.
But in 2014, amid the Ebola epidemic, only 90,717 kids in Liberia were inoculated against measles, according to figures from that nation’s Ministry of Health and Social Welfare that UNICEF shared with Scientific American. That translates into only 58 percent of children under the age of one being immunized against measles. During that time vaccination coverage may have varied widely from region to region, and many health facilities may have been closed or only partially functioning.
Worst-case scenario
The good news is that UNICEF has not heard about any recent large measles outbreak in Liberia, says Sheldon Yett, UNICEF’s representative in Liberia. And in the past few months that nation has made strides against its Ebola outbreak; it is currently on track to be declared Ebola-free if no new cases develop through early April. As a result, some immunization efforts for measles are resuming. UNICEF has already restarted its inoculation efforts in Liberia in the past couple months for various childhood vaccines including measles and expects to launch a countrywide measles and polio vaccination campaign in May, says Kamrul Islam, chief of child survival and development for UNICEF in Liberia.
Updated information on vaccine coverage since the Lessler team made their projections also suggests disruptions to routine vaccination may not have been quite as severe as originally feared. Instead of the 75 percent drop in vaccination rates used in the study, Lessler now says a drop of 25 or 50 percent may be more appropriate. But that is hardly comforting because, “Even if the reduction is only 25 percent, the same methods find 500 to 4,000 additional deaths compared to what would have happened at baseline,” Lessler says. “I know that international health care organizations, including the WHO and the Centers for Disease Control, are very much aware of this as a problem, but they are of course balancing many different competing priorities,” he says. Each month of vaccine gaps, however, increases the risk of a serious outbreak of measles or another preventable disease.