Two new Ebola vaccines have passed an important test, protecting monkeys against the strain of the virus responsible for the current deadly outbreak, researchers reported on Wednesday. Only one dose was needed, and there were no apparent side effects.

The vaccines have not yet been tested in people, but safety trials in healthy volunteers will probably begin early this summer, said Thomas W. Geisbert, an Ebola expert at the University of Texas Medical Branch in Galveston, and the senior author of a report published on Wednesday in the journal Nature.

Tests in nonhuman primates are an important step, because those animals are far more closely related to humans than are other lab animals.

The study of the new vaccines involved 10 macaques. Eight were vaccinated, and two, as controls, were not. The vaccinated animals showed no signs of side effects from the vaccine, Dr. Geisbert said. On the 28th day after the vaccines were given, all the monkeys were injected with Ebola virus from the current outbreak. No vaccinated monkeys became ill, but the unvaccinated ones both died within a week.