Some 2.5 million people will be vaccinated in the initial stage, which will last two months, Sanchez said.
Elderly care home residents and those looking after them will be first in line along with frontline healthcare workers.
The second stage of the vaccination campaign will begin in March and by “May or June, between 15 million and 20 million Spaniards will have been vaccinated,” Sanchez said.
He did not specify who would be vaccinated in the second stage but Spanish authorities have identified 15 priority groups, including the elderly and people with underlying health conditions.
“The third stage, when vaccines will be more widely available, will allow us to cover the entire population,” Sanchez added, without giving a timeline for completing the vaccination programme.
The government has said Covid-19 vaccination will not be mandatory.
Madrid has announced supply deals to receive 105 million doses of Covid-19 vaccines from several different labs. Most vaccines under development require two doses to work.
Although Spain has been one of the worst-affected countries in Europe, with more than 1.6 million infections and over 46,000 deaths, the country has brought down its incidence level to 240 cases per 100,000 inhabitants, one of the lowest levels in the European Union.