Hand-hygiene mitigation strategies against global disease spreading through the air transportation network

Christos Nicolaides; Demetris Avraam; Luis Cueto-Felgueroso; Marta C. González; Ruben Juanes

individuals are infected t = 0) and the epidemic expansion all over the world due to the mobility of infected agents is recorded. In the status quo scenario, we consider that hand cleanliness level is on a 20% steady state at each airport in the world. This percentage represents the fraction of individuals with washed hands at any moment. The rate of hand washing per hour that corresponds to 20% cleanliness is equal to 0.12 h -1 (see Table 2 ). We rank the airports in respect to TSD metric and we observe that LHR has the greatest impact while LAX, JFK, SYD and CDG are among the five most influential spreaders worldwide. Using the same order of airports, we repeat the simulations, by increasing the hand washing engagement rate homogeneously at all airports to achieve global hand cleanliness levels of 30%, 40%, 50% and 60%. For each hand washing engagement rate (or hand cleanliness level) we analyse the changes in the impact of contagion. Figure 3A shows the early-time evolution of the fraction of affected individuals over the first two weeks after a disease is seeded at DXB (Dubai Airport). Its observed that with the increase of hand cleanliness level at all airports from 20% to 60% there is a significant reduction in the percentage of the affected individual in the total population from around 1.5% to less than 0.5%. In Figure 3B we demonstrate the spreading power of the most influential spreader airports measured by TSD of infected individuals two weeks after a disease was initiated at each of these major airports, at 20% (status quo), 30%, 40%, 50% and 60% of homogeneous hand cleanliness. A drastic, very significant reduction in TSD is observed with the increase of cleanliness level, verifying that hand-hygiene is one of the most important factors to control or even prevent an infection. For example, the spread of infection seeded in LHR was covered about 5 · 10 5 square meters around the mass centre of the infection within two weeks, while infected area was reduced to less than 2 · 10 5 square meters when cleanliness level increased from 20% to 60% globally. The relative to the status quo reduction of the disease impact is calculated by (T SD 20% − T SD X )/T SD 20% for the TSD metric or (PREV 20% − PREV X )/PREV 20% for the disease prevalence metric, where the cleanliness level X increases from 30% to 60% worldwide. The results are shown in Table 2 indicate a significant reduction of the impact of a disease worldwide by 24% to 69% depending on the hand washing engagement rate worldwide using the calculated by the TSD (or by 18% to 55% as calculated by the global prevalence of the disease).