An Ebola breakthrough

The world officially has an Ebola vaccine.

European regulators approved the marketing and distribution of Ervebo, a vaccine from the drugmaker Merck, which can be used against the most-common strain of the virus. Already in use in the Democratic Republic of Congo, it has been shown to be 97.5 percent effective.

The approval of the new vaccine likely won't change the situation in the DRC, which is still gripped by the second-worst Ebola outbreak in history (though there are indications the situation may be improving). Ervebo is already deployed there under a "compassionate use" agreement and has protected more than 90,000 people.

But with the European approval of Ervebo and the subsequent pre-qualification by the World Health Organization, the vaccine can be speedily deployed in future outbreaks without jumping through the regulatory hoops of acquiring a compassionate use agreement. And in an Ebola outbreak, speed is of the essence.

It's also worth considering the speed with which the vaccine has been developed. An Ebola vaccine was barely on the international research radar when the Ebola outbreak began in West Africa five years ago. Now the world has a critical weapon to slow future outbreaks.