AGI – Four possible scenarios for the autumn evolution of the Covid epidemic in Italy: from the one with a low incidence to the fourth, in which the situation has practically got out of hand, the Rt index is above 1.5 and within a month, a month and a half, the health services are likely to go into severe pain. These are the forecasts contained in the document drawn up by the Ministry of Health and the Higher Institute of Health entitled ‘Prevention and response to COVID-19: evolution of strategy and planning in the transition phase for the autumn-winter period’. The report focuses on a series of variables (the transmissibility of the virus in schools, in the workplace, the impact of mobility, but also the degree of acceptance of the measures by the population and obviously the responsiveness of the system), based on of which the four scenarios have been identified.
The first speaks of a “localized transmission situation (outbreaks) substantially unchanged compared to the period July-August 2020, with regional Rt above the threshold for limited periods (less than 1 month) and low incidence, in the event that transmissibility does not systematically increase in early autumn, schools have a modest impact on transmissibility and regional health systems are able to track and keep new outbreaks under control, including school ones “.
The second scenario becomes more complex: “Situation of sustained and widespread transmissibility but manageable by the health system in the short-medium term, with regional Rt values systematically and significantly between Rt = 1 and Rt = 1.25 (i.e. with estimates of the 95% Confidence Interval – 95% CI – of Rt between 1 and 1.25), in the event that new outbreaks, including school outbreaks, are not fully tracked, but the transmission potential of SARS-CoV-2 is still greatly limited with ordinary and extraordinary containment / mitigation measures “. epidemic with these characteristics, the document reads, “could be characterized, in addition to the evident impossibility of containing all outbreaks, by a constant increase in the incidence of cases (at least symptomatic ones; it is in fact possible that a reduction in the percentage of asymptomatic cases identified with respect to the total given the impossibility of carrying out the epidemiological investigation for all new outbreaks) and corresponding increase in hospitalization rates and hospitalizations in t intensive care “. The growth in the number of cases “could however be relatively slow, without causing a significant overload of assistance services for at least 2-4 months”.
The third scenario instead prefigures one situation of “sustained and widespread transmissibility with the risk of maintaining the health system in the medium term, with regional Rt values systematically and significantly between Rt = 1.25 and Rt = 1.5 (i.e. with 95% CI estimates of Rt between 1.25 and 1.5), and in which it is possible to limit the transmission potential of SARS-CoV-2 only modestly with ordinary and extraordinary containment / mitigation measures “. In this case,” a faster growth in the incidence of cases is expected than in scenario 2, lack of ability to track transmission chains and initial signs of overload of care services following the increase in cases of high clinical severity (with increased occupancy rates of hospital beds – critical and non-critical area) attributable to a high or very high level of risk based on the weekly monitoring system. The growth in the number of cases could lead to an overload of assistance services within 2-3 months “. However, it is important to note that” if the epidemic were to spread mainly among the younger age groups, as observed in the period July-August 2020 , and if it were possible to protect the most fragile categories (eg the elderly), the time margin within which to intervene could be greater “.
Finally, the fourth scenario, the worst: “Situation of uncontrolled transmissibility with criticality in the health system in the short term, with regional Rt values systematically and significantly greater than 1.5 (i.e. with 95% CI estimates of Rt greater than 1.5). Even if an epidemic with these characteristics would lead to more aggressive mitigation and containment measures in the affected territories, such a scenario could quickly lead to a high number of cases and clear signs of overload of welfare services, without the possibility of tracking the origin of new cases. The growth in the number of cases could lead to an overload of care services within 1-1.5 months, unless the epidemic spreads predominantly among the younger age groups, as observed in the period July-August 2020, and managed to protect the most fragile categories (eg the elderly). In this regard, it should be noted that it appears rather unlikely to be able to protect the most fragile categories in the presence of an epidemic characterized by these values of transmissibility “.