The announcement states that only the other 2 vaccines will start Phase 1 trials in 2021, and is silent on Phase 1 trials on the Nipah vaccine. There's development work before that though: in vitro trials and trials on animal models. Depending on the outcomes, they can move to Phase 1 trials, where, just like they did for the Covid vaccine, they'll look at the safety (i.e. if there are side-effects) and the immune response (how many antibodies, and what type of T-cell and B-cell response there is). If they do that, they would be in a position to quickly proceed to Phase 2/3 trials in case there's an outbreak anywhere in the world.