Scenarios of diffusion and control of an influenza pandemic in Italy

Abstract

To predict the spread of a pandemic strain of influenza virus in Italy and the impact of control measures, we developed a susceptible-exposed, but not yet infectious-infectious-recovered, and no longer susceptible (SEIR) deterministic model with a stochastic simulation component. We modelled the impact of control measures such as vaccination, antiviral prophylaxis and social distancing measures. In the absence of control measures, the epidemic peak would be reached about 4 months after the importation of the first cases in Italy, and the epidemic would last about 7 months. When combined, the control measures would reduce the cumulative attack rate to about 4.2%, at best, although this would require an extremely high number of treated individuals. In accordance with international findings, our results highlight the need to respond to a pandemic with a combination of control measures.

Fig. 1

Weekly attack rate, by age group, with no control measures.

Fig. 2

Impact of different combinations of control measures considering the use of a pre-pandemic vaccine provided to all categories (I–IV).

Fig. 3

Total attack rates for different values of R₀, with no control measures or selected control measures.