What next in the fight against Lassa fever?

ABUJA, Nigeria — Fifty years since Lassa fever was first identified in Nigeria, the country is grappling with yet another outbreak, now set to be the worst on record, with 72 deaths confirmed in the first six weeks of the year — albeit in part because of improved disease reporting, according to the government.

Like Ebola, Lassa fever is a hemorrhagic fever and has similar symptoms — though it has an average fatality rate of around 15 percent against Ebola’s 50 percent, and can be treated using the antiviral drug ribavirin in its early stages. Spread by rats, it is endemic in Benin, Guinea, Liberia, Mali, Sierra Leone, and Nigeria. In some areas, it is estimated that 10-16 percent of people admitted to hospital annually have the disease.

As with Ebola, much hope is pinned on the development of a Lassa fever vaccine. A number of promising research projects were presented at the 2019 Lassa Fever International Conference held in Abuja, Nigeria, earlier this year, though most are in the early stages — including one from Inovio supported by the Coalition for Epidemic Preparedness Innovations; and another from the Viral Hemorrhagic Fever Consortium.

But experts involved in the control of outbreaks in West Africa are reserving their optimism, anticipating that the vaccines in development may be protective for certain varieties of Lassa fever, but not for all; and pointing to a number of practical obstacles in rolling them out.

Similar problems for all

As the list of candidates for a Lassa fever vaccine grows, a consistent set of challenges is emerging. Some approaches, including the VHFC research, involve a cocktail of immunotherapeutic components, which takes longer to test. The vaccine would also need to deliver results in often isolated, high-risk areas. The cold chain storage challenge experienced with the deployment of the Ebola vaccine in the Democratic Republic of the Congo has highlighted one such problem — many areas where the vaccines are needed most don’t have a reliable power supply to guarantee storage temperatures.

The World Health Organization estimates that more than half of vaccines may be wasted globally each year because of temperature control, logistics, and shipment-related issues. If and when the Lassa fever vaccine becomes available, its delivery plan will have to overcome numerous obstacles, including poor infrastructure, lack of specialized equipment, and monitoring capabilities.

There is also the issue of immunization coverage. According to WHO, global efforts to increase vaccine coverage have stagnated; and progress on the Global Vaccine Action Plan, a roadmap to prevent millions of deaths through more equitable access to vaccines by 2020, is off track.

Vaccine hesitancy is also gaining ground, now identified as one of the top 10 threats to global health by WHO, in part because of complacency, inconvenience in accessing vaccines, and lack of confidence in them, it says. In DRC, some residents of the areas worst affected by Ebola rejected the vaccine over suspicions around it. 

“They say if you take it you will become infertile, it will kill you, it has bad effects," Dr. Maneno Muhindangabo Henry, who leads a community surveillance unit in DRC, told Sky News. There were similar rejections of polio vaccines in Nigeria in 2017, prompting the government to introduce a two-year jail term for parents who refuse to vaccinate their children.

“When you launch a vaccination campaign, communities already have their own approach to health care and we need to understand this because, in a sense, we are trying to displace it,” said Heidi Larson, an anthropologist and leader of the Vaccine Confidence Project at the London School of Hygiene & Tropical Medicine.

Back to basics

Given the challenges of rolling out a Lassa fever vaccine, many stakeholders believe it would be unwise to pin too much hope on it and point to the importance of implementing the basics in infection prevention and control, or IPC. Despite the simplicity of methods such as hand washing, glove disinfection, and protective clothing, they are not well used by health care workers, who continue to be infected — and die — from the disease.

Nigeria’s National Guidelines for Lassa Fever Case Management state that IPC is an essential aspect of clinical management. “But how can we expect people in rural areas, who have no idea about virology and disease prevention, to successfully practice IPC, when health care professionals themselves are failing in that regard?” public health expert Dupe Adeniji told Devex.

Elsie Ilori, technical team lead for Nigeria’s National Lassa Fever Working Group, explained that health care professionals often put their lives at risk because they prioritize quick treatment of patients. Dr. Hilde De Clerck, emerging infections adviser for Médecins Sans Frontières, added that it would take a lot of extra resources to ensure that personal protective equipment and other hygiene tools were available wherever they are needed. Health care workers, too, would require constant reminders to adhere to the rules.

She also drew attention to the debate over the reason for the surge in reported cases. One school of thought points to climate change, with hotter temperatures pushing rodents out of hiding places and into closer contact with humans. Another group believes there is no true increase in the number of cases, only an increase in detection — although even so, there are likely to be many more cases than currently reported.

With the detection system centralized in teaching hospitals, less severe cases that may not require treatment are likely never picked up, De Clerck explained. She also noted that in spite of vast communication efforts, there is still a widespread lack of understanding of the disease, meaning many people don’t know the importance of isolation and hygiene when they develop symptoms.

But De Clerck believes there are still steps affected countries can take to quickly reduce the number of cases and lower mortality rates. One is mapping, to reveal where the cases are originating, followed by targeted response in the areas most affected, enabling countries to use their resources more effectively. She also noted the importance of good surveillance, early detection, and early treatment.

Having these conditions in place, experts said, will help prepare the ecosystem for the eventual arrival of vaccines.