Conjectures concerning the explanation of recurrent patterns in COVID-19 spread dynamics based on time-variant networks.

Abstract

The paper discusses conjectures concerning patterns in virus spread observed in the Covid-19 event, including fluctuations of activity under constant environmental conditions, plateaus of near-constant activity, and rapid wild-type replacement at rather low levels of population immunity. Based on models of time-variant networks, it is shown that the patterns can be explained if spread dynamics result from superposition of three components: Continuous activity in reservoirs with limited fluctuation where fluctuation of group members allows transmissions from active cases to new arrivals before the active cases leave or reach the end of the contagious period. Hospitals are the obvious candidates for these reservoirs. The second component is propagation within stable groups, such as families, office staff, or religious groups. In addition, there are outbursts in temporary groups. The second and third components multiply case numbers but, due to strong segmentation of the population, do not support self-sustained spread which would allow the previous wild-type to coexist with a mutant strain until population immunity gets too high.