With outbreak spreading, WHO worries Merck's Ebola shot may run scarce

Responders have used Merck's Ebola vaccine during two outbreaks in the Democratic Republic of Congo this year. (WHO)

Nearly five months into an Ebola outbreak in the Democratic Republic of Congo, the disease is spreading closer to urban population centers, and that has health officials worried the vaccine stockpile won't meet demand, Stat reports.

Merck has maintained a supply of 300,000 doses, but around 42,000 doses have been used over the past several months as officials work to vaccinate in a “ring” strategy, using the unapproved vaccine on an emergency basis, according to the publication. The idea is to stop spread of the disease by administering shots to healthcare workers and infected people's contacts.

And like most vaccines, Merck's shot requires long production times. It takes about a year to make, a Merck representative told Stat. Plus, most of Merck's supply is stored in bulk, and it takes 4 to 5 months to convert bulk doses into vials that can be used on the ground, the company said. 

Officials used Merck’s vaccine in a previous, smaller outbreak in the Democratic Republic of Congo this year, and in July, WHO reported that the outbreak had “largely been contained.” Only days later, however, a new outbreak sprung up in a war-torn region.

As of the beginning of December, WHO reports 405 confirmed cases and 220 confirmed deaths in the ongoing outbreak. The agency says there’s a “very high” risk Ebola could spread to other provinces in the country or to other countries. 

Merck licensed its Ebola vaccine from NewLink Genetics amid the deadly 2014 Ebola outbreak in western Africa and accelerated development in response to that emergency. In all, more than 11,000 people died in that outbreak. 

Now, Merck is ready to seek FDA approval for the vaccine. Under a FDA breakthrough tag, Merck started a rolling submission for its shot last month; Merck expects to finish the process next year. The vaccine hasn’t yet won international approvals, but vaccine advisers for the World Health Organization have recommended its use to combat outbreaks when no licensed vaccines are available. 

In a previous phase 3 “ring” study targeting people who’d been exposed to the virus and their contacts, the vaccine demonstrated 100% efficacy. Aside from Merck, GlaxoSmithKline, Johnson & Johnson, and other smaller biotechs such as Inovio Pharmaceuticals are developing Ebola vaccines.