More than a hundred COVID-19 vaccines based on different technologies are currentlyin the clinical phase of development around the world. More than a dozen derived from different platforms have been approved by regulatory entities in several countries and are used to immunize the world's population.~The dynamics of the COVID-19 pandemic, the emergence of variants, the magnitude and durability of the immune response, the effectiveness of approved vaccination schemes, as well as the possibility of combining vaccines from various platforms, are some of the issues to be facedin public health decision-making, in order to deliver the best protection standards to the population.~Given the dynamics of the disease in Argentina, the access to different COVID-19 vaccination alternatives requires the development of various strategies, such as stratifying the population sampled by the risk of being infected or transmitting the disease, the agreement for the acquisition of vaccines produced by multiple laboratories simultaneously, setting as a priority first dose vaccination to a higher number of people in a shorter period of time and completing the schemes already started.~The pandemic has revealed the capacity of our country to carry out research studies that produce evidence to face the new challenges posed by COVID19 and, particularly,to implement vaccination as one of the main tools to reduce the health impact it generates-for example,six months after the start of the vaccination campaign, results demonstrate the positive impact of this strategy and its effectiveness.~Models based on heterologous immunization schemes with vaccines from different platforms require evaluation by means of clinical trials,in order to show whether they are not less effective than homologous schemes already established. This is achieved through comparative evaluation of their immunogenicity, efficacy and reactogenicity with studies considering implementation possibilities, adaptiveness and response to real life situations.~Hence, the Ministry of Health propoundsthe development of a collaborative network for the integration of studies on vaccination strategies against COVID-19 with the use of heterologous schemes based on the evaluation of their non-inferiority, compared to homologous vaccination schedulesalready implemented worldwide.~The Argentine Ministry of Health looks forward to generating solid scientific evidence that supports decision-making in health policies, with broad federal participation and common objectives.
Randomized, open, multicenter, collaborative and adaptive non-inferiority trial to evaluate the immunogenicity and reactogenicity of the heterologous vaccination schedules made up of the combination of vaccines available in Argentina (Sputnik-V, AstraZeneca, Sinopharm and Moderna); and to compare the immunogenicity and reactogenicity of heterologous and homologous vaccination schedules.