[Solidarity, covid-19 and a lever without fulcrum.].

Herd, or collective, immunity has been a permanent reference all along the Covid-19 pandemic, often misunderstood as a technical synonym of "epidemic end" once a threshold value of immunized people is reached. The pandemic development has shown that with current variants transmissibility and current vaccines such critical threshold cannot be reached. An effective collective immunity is however attainable, the stronger the higher the population proportion of vaccinated people.