Coronavirus: How many phases does the development and manufacture of a vaccine have?

Last week, Pfizer reported that it had developed a vaccine against the coronavirus whose effectiveness was 90%, although yesterday it raised it to 95%. For its part, Modern continued with the good news and on Monday announced that the cited parameter in his remedy was 94.5%.

As reported by both companies, the next step will be for the vaccines to receive authorization from regulatory bodies. Once this happens, it is expected that between the end of this year and the beginning of 2021, the first groups begin to be vaccinated that each country decides, since mass vaccination is scheduled for the first summer.

In addition, research to find more vaccines that are effective against the coronavirus continues to advance around the world. According to the records of the World Health Organization (WHO), there are 164 projects that are in the preclinical phase.

Keep in mind that the process from the beginning of a study about a vaccine until ends and is available for your use it can take months. Before declaring a vaccine effective and safe, must pass the following phases:

Exploration phase

It is the initial work, basic research is developed, work that is fully performed in a laboratory. In this stage the goal is to find natural or synthetic antigens that can help treat or prevent a certain disease.

Preclinical phase

Once antigens that can be effective have been obtained, the next step is to proceed to test these prototypes. The study can be carried out in cell cultures or in animals, which are usually monkeys or mice. This trial seeks to verify the safety of the possible vaccine and the capacity of the organism to achieve an immune response.

Human testing: phase I

If the above trials are positive, it is time to start human trials. However, the group of people with whom one works initially is small. These are usually healthy adult individuals in a number that does not exceed 100 subjects. In this phase, we begin to evaluate whether the vaccine project with which we are working causes immunological and biological effects, in addition to confirming its safety.

Human testing: phase II

At this stage of the investigation, the trials are extended to larger groups, usually ranging from 200 to 500 people. Study volunteers can be all types of patients and not exclusively healthy individuals. These tests evaluate the efficacy of the vaccine under development and whether the dose applied produces the desired results, as well as determining the best way to administer the drug.

Human testing: phase III

In this phase of the clinical study, the vaccine can be tested in thousands of people. with the aim of detecting possible side effects that might not have been previously detected with more, smaller groups. Due to the wide scope of these trials, patient follow-up is done from multiple centers.


Once all phases of the investigation have been passed with positive results, the laboratory that has developed the vaccine makes the request for approval to the health authorities. In the case of Spain, the Spanish Agency for Medicines and Health Products (AEMPS), attached to the Ministry of Health, is the body that examines the request. If the vaccine receives official authorization, it is manufactured on a large scale. Subsequently, with the drug already available in pharmacies and hospitals, a final control phase can be applied to measure its real efficacy on a large scale.