The number of Ebola cases dropped sharply in recent months but a sixth new case was confirmed Tuesday in Liberia in what health officials fear may be a new wave of the outbreak, BusinessInsider reports.

Researchers say the Liberian flare-up underscores the need to push forward with vaccines that may help control this and future outbreaks.

Two second-phase Ebola vaccine trials began Wednesday with volunteers in Senegal, the U.K. and France getting immunizations developed by Johnson & Johnson (U.S.); Bavarian Nordic (Denmark); and GlaxoSmithKline (U.K.), BusinessInsider reports in a Reuters story by Kate Kelland.

The mid-stage trials aim to test safety of the vaccines and to assess whether they produce an immune response against the deadly virus.

In Galveston, Texas, scientists are using primates to test an inhalable version of an Ebola vaccine, according to Pix11. Tests have shown that just one dose was strong enough to protect macaque monkeys exposed to 1,000 times the fatal dosage of the disease.

Researchers want to expand the vaccine to human test subjects but the last Ebola vaccine that was successful in primates, failed on humans, according to the report. If this vaccine works on humans, it could be distributed without doctors — a benefit for countries lacking strong healthcare systems.

Development of these and other vaccines was accelerated in response to Ebola outbreaks in West Africa that claimed at least 11,200 lives in Guinea, Sierra Leone and Liberia, BusinessInsider reports.

The Johnson & Johnson and Bavarian Nordic trials need more than 600 healthy adult volunteers in Britain and France.

Bavarian said it hoped to launch a later phase of its trial in Africa later this year involving 1,200 volunteers, but large clinical trials have recently been thwarted by the drop in case numbers.

Previously planned trials of Johnson & Johnson, Bavarian Nordic and GlaxoSmithKline shots in West Africa have been struggling to recruit volunteers with enough exposure to Ebola to prove whether their vaccines are doing the job and preventing infection, according to BusinessInsider.

The second trial will be conducted in Senegal and uses two vaccines tested first in people at Oxford University’s Jenner Institute and being developed in a partnership with GlaxoSmithKline. The first, based on a chimpanzee adenovirus, is designed to stimulate, or prime, an initial immune response, while the second is designed to boost that response.

Ebola is fatal in humans about 50 percent of the time, while the mortality rate for rhesus macaques used in Ebola research is greater than 95 percent, HuffingtonPost reports.

The aerosolized vaccine is the first of its kind to be developed and tested for Ebola. Once approved, it will advance to phase 1 clinical trials — that is human subjects –run by the National Institutes of Health, once approved., according to HuffingtonPost.

There were 30 confirmed cases of Ebola in West Africa in the week through July 5, according to WHO.