Novavax Inc. has begun early-stage testing of its Ebola vaccine in humans, the company said, less than five months after entering the race to develop a shot for the deadly virus.

The company said on Thursday it has the means to manufacture millions of doses of its vaccine.

After appearing to subside earlier this year, the number of new Ebola cases in West Africa has risen for the second week in a row, the World Health Organization said on Wednesday.

The worst outbreak of the virus on record has killed at least 9,177 people out of 22,894 recorded cases, overwhelming health-care systems in Guinea, Liberia and Sierra Leone, the three most-affected countries.

All Ebola vaccines under development face the same challenges: they must be cheap, readily producible and easy to handle and transport to Africa.

Early human data on a vaccine being developed by GlaxoSmithKline Plc , the most advanced to date, has suggested that a single dose may not provoke an immune response strong enough to protect people exposed to Ebola.

Other potential vaccines include those being developed by a NewLink Genetics Corp and Merck & Co Inc collaboration and by Johnson & Johnson and Bavarian Nordic A/S.

Gaithersburg, Maryland-based Novavax said its vaccine is being tested in 230 healthy volunteers in Australia. Each subject, aged between 18 and 50, will receive two intramuscular injections 21 days apart.

The trial is backed by study data that shows every animal vaccinated was protected from a lethal dose of the virus, the company said in a statement.

Shares of Novavax have risen 61 percent since Oct. 27, when the company revealed it was testing its vaccine in non-human primates.