COVID-19 vaccine race: analysis of age-dependent immune responses against SARS-CoV-2 indicates that more than just one strategy may be needed

In December 2019, a novel respiratory coronavirus named SARS-CoV-2 appeared in China, causing the disease termed COVID-19 that has caused millions of infections worldwide. In this article we have analyzed existing evidence on the immune response against SARS coronaviruses in order to understand the possible outcome of a vaccine for COVID-19. From our analysis it becomes clear that there is a big difference in the immune response against SARS in children, young adults and the elderly, both at the innate and adaptive levels. Taking this information into account, we have studied the strategies that are being used for development of COVID-19 vaccines. We discuss the perspectives for obtention and worldwide distribution of reliable vaccines using this perspective. The conclusion is that different vaccines may be protective for different age segments within the population, depending on the strategy used for their design. Therefore, it will become necessary for several vaccines to reach the finish line, not only to ensure availability, but also to guarantee an adequate immune response at the individual level.