  The potential waning of the vaccination immunity to COVID-19 could pose
threats to public health, as it is tenable that the timing of such waning would
synchronize with the near-complete restoration of normalcy. Should also testing
be relaxed, we might witness a resurgent COVID-19 wave in winter 2021/2022. In
response to this risk, an additional vaccine dose, the booster shot, is being
administered worldwide. In a projected study with an outlook of six months, we
explore the interplay between the rate at which boosters are distributed and
the extent to which testing practices are implemented, using a highly granular
agent-based model tuned on a medium-sized U.S. town. Theoretical projections
indicate that the administration of boosters at the rate at which the vaccine
is currently administered could yield a severe resurgence of the pandemic.
Projections suggest that the peak levels of mid spring 2021 in the vaccination
rate may prevent such a scenario to occur, although exact agreement between
observations and projections should not be expected due to continuously
evolving nature of the pandemics. Our study highlights the importance of
testing, especially to detect asymptomatic individuals in the near future, as
the release of the booster reaches full speed.
