  In all Countries the political decisions aim to achieve an almost stable
configuration with a small number of new infected individuals per day due to
Covid-19. When such a condition is reached, the containment effort is usually
reduced in favor of a gradual reopening of the social life and of the various
economical sectors. However, in this new phase, the infection spread restarts
and a quantitative analysis of the regrowth is very useful. We discuss a
macroscopic approach which, on the basis of the collected data in the first
lockdown, after few days from the beginning of the new phase, outlines
different scenarios of the Covid-19 diffusion for longer time. The purpose of
this paper is a demonstration-of-concept: one takes simple growth models,
considers the available data and shows how the future trend of the spread can
be obtained. The method applies a time dependent carrying capacity, analogously
to many macroscopic growth laws in biology, economics and population dynamics.
The illustrative cases of Singapore, France, Spain and Italy are analyzed.
