The phase 3 trial will be carried out in nine hospitals across Spain involving volunteers both with and without underlying health conditions, the national medicines agency AEMPS said in a statement on Wednesday.
Trials of the two-dose vaccine will involve up to 30,000 volunteers in Belgium, Colombia, France, Germany, South Africa, Spain, the United Kingdom, the United States and the Philippines, said the agency.
The agency did not say how many people would take part in Spain, only that the hospitals involved would begin recruiting volunteers “as soon as possible”.
Twenty percent of the volunteers will be under the age of 40, and 30 percent will be over 60. They will be given either a dose of the experimental vaccine dubbed Ad26.COV2.S or a placebo.
“These trials are essential to guarantee the quality, safety and effectiveness of vaccines,” the agency said, indicating the results would be made available after all the data is analysed at the end of the trials.
Johnson & Johnson carried out mid-stage phase 2 trials of the vaccine in September in Spain and other countries.
This will be the first phase 3 trial in Spain for a vaccine against Covid-19, according to the medicines agency, a unit of the health ministry.
According to World Health Organization protocols, a candidate vaccine must complete three phases of clinical trials to be approved for industrial production.
Phase 3 trials are the largest. A vaccine is deemed ready to move into industrial production once this last phase provides clear evidence of its safety and efficacy.
Two other firms, Pfizer and Moderna, announced this week that their candidate vaccines had shown over 90-percent efficacy in their phase 3 trials.