AstraZeneca agrees to supply Europe with 400 mil doses of COVID-19 vaccine

It may seem too soon to be making this kind of deals, after all the vaccine candidate is still on trials, but it is actually the perfect timing. This is a very delicate situation and many countries are in a dangerous position economically, "betting" on a strong candidate this early lets them plan accordingly having only one worry (the vaccine working or not) instead of two (the vaccine working on one hand and procuring it on the other)

Is this antidote GUARANTEED ???.