On a hot and humid morning in February 2021, Evans Lablah, an immunization specialist with UNICEF in Liberia, was working at his desk when he received an email with unexpected news: Variant poliovirus had been detected in the sewage system of Monrovia, the capital city.
It was a stunning setback. Liberia had been declared free of wild poliovirus 11 years earlier, three years after Lablah got his start in public health in a job overseeing a polio vaccine campaign in a rural district. Since then, the country had routinely tested sewage samples to look for signs of diseases that could be circulating in communities—an important component of a strong public health system.
The detection of variant poliovirus—a mutated strain of the weakened virus in oral polio vaccine–in the city’s sewage triggered a public health emergency and the formation of a rapid response team to search for the exact source in Monrovia. Lablah, by then a seasoned expert in vaccination campaigns, became part of that team, which included both UNICEF and World Health Organization staff.
Evans Lablah reviews materials on his computer at the UNICEF office in Monrovia, Liberia. Photo credit: ©Gates Archive/Carielle Doe
Pursuing a career in health care
Lablah grew up in Monrovia during Liberia’s 14-year civil war, which lasted from 1989 to 2003. The second of five children, he enjoyed playing soccer and visiting his grandparents in their rural village, where he’d scare away birds from the rice fields and hunt antelope. But it was hard to escape the brutality of living in a war zone.
By the end of high school, he was desperate to leave the endless fighting. He had always wanted to study medicine, but the war had disrupted training at the country’s two medical colleges.
In 2001, Lablah received a scholarship to study nursing at a university in Morocco, despite not speaking Arabic or French, the main languages used in education there. He quickly began studying French, and in 2006 he received a nursing degree and returned home.
Liberia’s health system urgently needed trained workers. More than 95% of its health facilities had been destroyed or damaged in the fighting, and fewer than 20 doctors remained to treat the country’s 3.4 million people.
Lablah was sent to Grand Cape Mount County, a district in the northwest corner of Liberia whose population of 120,000 was scattered in remote villages. In global health, these are known as “last mile” areas because they are the hardest to reach with health services and are typically underserved.
Lablah and a midwife were the only trained health workers at one of the district’s five health clinics. They delivered babies and provided primary care services, including routine immunizations, nutritional screening, and maternal health care. Their interaction with patients was often the only contact locals had with the health system. The center lacked just about everything: regular electricity, running water, cellular service, and equipment such as ultrasound machines. Lablah’s US$145 monthly salary barely covered his food expenses.
“But as time went by,” he says, “I realized that this was a calling. It was about how I can contribute to humanity and make a difference.”
In 2007, Lablah became the district coordinator for polio campaigns and led a vaccination team to villages so remote that they had never been visited by a health worker. One of those places was Moila Island, which was an hours long walk from the next village and required stepping across a bunch of logs loosely tied together. In the team’s first attempt to reach the island, the worker carrying the vaccines fell into the water. The team was reluctant to try again, but Lablah reminded them that leaving any pocket unvaccinated would make the country vulnerable to future outbreaks. They returned the next day and vaccinated the 30 children on the island.
Over the next 15 years, Lablah’s commitment to community health care only deepened. Eventually, he joined the UNICEF Liberia team and began the hard work of strengthening Liberia’s immunization system to protect children from devastating diseases such as measles, polio, pneumonia, and diarrhea.
This was how he ended up sitting at a desk that day in 2021, staring in shock at the email announcing that polio had been detected in Monrovia’s sewage.
Polio makes a comeback
The positive sample came from the sewers of Redemption Ridge, a densely populated neighborhood in Monrovia. The team went to work trying to determine exactly who was infected so they could contain transmission of the virus.
Poliovirus is spread through contact with human waste, making young children—especially those living in settings that lack clean water and sanitation systems—the most susceptible to exposure. The virus enters the nervous system and can cause permanent paralysis and even death. Most infected people do not show any symptoms, however, so they never know they are infected. This gives the virus time to multiply inside their intestines before being released through their stool. The virus can then spread undetected until there is a case of paralysis, usually in an unvaccinated person, or it’s caught during regular testing of sewage samples.
The world has been close to eradicating all types of polio for decades. But those efforts have fallen short because of longstanding challenges including low immunization coverage rates, unsanitary living conditions, setbacks related to armed conflict, and weak health systems.
Lablah and the rest of the rapid response team worked double shifts to investigate the source of the outbreak, and hundreds of other diseases investigators knocked on as many as 100 doors a day, asking residents if anyone in the family had experienced sudden paralysis symptoms.
“It’s quite a massive undertaking, and the fact that it has to be done immediately when no one is expecting it takes a toll on the delivery of routine health services,” says Lablah.
The investigation identified two cases of sudden paralysis that had occurred more than 60 days earlier, but the source of the positive sewage sample was never identified. Fifty stool samples collected from healthy children under age 5 in Redemption Ridge all tested negative for the poliovirus.
An effective rapid response includes a vaccination campaign to cover the outbreak area and those at risk. In Liberia, that meant vaccinating more than 800,000 children over a four-day period one month after detection of the virus, to stop the outbreak from spreading.
About 9,000 vaccination workers fanned out across the country’s 15 counties, visiting schools, churches, and homes. Lablah zigzagged across the country to deliver supplies and check conditions, making his way through slums and navigating dirt roads that had turned into knee-high pools of mud. He started at 5 a.m. each day and didn’t stop until 10 p.m.
Cop
One of the biggest challenges was vaccine hesitancy. One mother was reluctant to vaccinate her 3-year-old son, saying that he had received multiple doses during previous campaigns.
Lablah explained that the poliovirus can mutate and spread in places where immunity levels aren’t high enough, and that new vaccines had been created to protect against those variants. He also said to her, “If he gets polio, he’s going to be dependent on you for the rest of his life.” He told her that she was healthy because her parents had gotten her vaccinated. The mother decided to have her son vaccinated.
“I always emphasize to the vaccination teams that they should not just conclude that hesitancy means refusal. When we explain properly why the vaccine is important, it results in the child getting vaccinated,” says Lablah. In Liberia, community and religious leaders are active in the campaigns, listening to concerns and reassuring community members that the vaccines are safe and necessary to protect their children.
That initial vaccination campaign and a second one in May of that year reached about 1.8 million children—more than 95% of the target age group.
Forward to eradication
Since 1988, cases of wild poliovirus worldwide have dropped by 99%. While mutated forms of the virus continue to pop up in a few places around the world, increased surveillance efforts, stronger routine immunization systems, and vaccination campaigns have limited their impact.
In 2024, Liberia reported another positive sample, prompting supplemental vaccination campaigns. But this time, the campaigns were coordinated with neighboring countries Sierra Leone, Mali, Burkina Faso, Guinea, and Ivory Coast. As of the first nine months of 2025, Liberia had not detected any poliovirus in sewage samples. Despite the setbacks, Lablah is confident that Liberia—and the rest of the world—will ultimately succeed in eradicating all forms of polio.
“It’s unacceptable to see success in sight and then give up,” he says. “We just need to be persistent.”
Source: Gates Foundation
