With vaccine in hand, Ebola response teams are struggling to track those who need it

The response team in North Kivu has vaccinated a prodigious number of people — more than 20,000 so far in the province and in parts of neighboring Ituri province, where a few cases have occurred. That count rises by hundreds of people most days.

“It’s extremely impressive,” Anne Rimoin, an associate professor of infectious diseases epidemiology at UCLA’s Fielding School of Public Health, told STAT.

But vaccination efforts were not conducted Monday in Beni, after the weekend’s violence there.

So far there have been 238 confirmed and probable cases reported in this outbreak and 155 deaths.

As gaps grow in the response team’s understanding of where the virus is circulating and who has been exposed, the capacity of the vaccine to contain the outbreak diminishes. Osterholm explained the problem as if it were an equation.

Conventional Ebola control measures — isolating the sick, identifying and monitoring the health of contacts of cases, and isolating them if they become symptomatic — are variable A in the equation. On their own, these measures have contained decades of Ebola outbreaks in the past.

But then along came vaccine, variable B in the equation. The Merck vaccine was proved to work during the West African outbreak of 2014-2015 and was first used as a containment tool in an outbreak in western DRC this past spring. That outbreak was brought under control fairly rapidly.

A plus B should lead to containment of the outbreak, potentially faster than in outbreaks past. But if A falters, B — the vaccine — can’t do the job on its own, Osterholm said. “It only works when you get it to the people who need it,” he said.

That’s because of ring vaccination, the type of vaccination strategy being deployed in North Kivu. It was used in the successful smallpox eradication campaign of the 1960s and 1970s.

The idea behind the strategy seems simple: Rather than trying to vaccinate everyone in a place where Ebola is spreading, focus on the people who are at risk of actually contracting the disease. Beni is a city of more than 200,000 people, but only a tiny fraction of them would have been exposed to the virus up to this point.

The goal is to throw up a wall of immunity that Ebola cannot scale.

But effective contact tracing is required to draw up the list of people who should be offered vaccine. And increasingly, contact tracing isn’t identifying all of the at-risk people.

Article Appeared @https://www.statnews.com/2018/10/23/ebola-response-teams-struggling-vaccine-tracking/

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