Eguíluz Víctor M, Fernández-Gracia Juan, Rodríguez Jorge P, Pericàs Juan M, Melián Carlos
Instituto de Física Interdisciplinar y Sistemas Complejos IFISC (CSIC-UIB), Palma, Spain.
Institute for Scientific Interchange (ISI) Foundation, Turin, Italy.
Front Med (Lausanne). 2020 Dec 15;7:563455. doi: 10.3389/fmed.2020.563455. eCollection 2020.
The Spanish government declared the lockdown on March 14th, 2020 to tackle the fast-spreading of COVID-19. As a consequence, the Balearic Islands remained almost fully isolated due to the closing of airports and ports, these isolation measures and the home-based confinement have led to a low prevalence of COVID-19 in this region. We propose a compartmental model for the spread of COVID-19 including five compartments (Susceptible, Exposed, Presymptomatic Infective, Diseased, and Recovered), and the mobility between municipalities. The model parameters are calibrated with the temporal series of confirmed cases provided by the Spanish Ministry of Health. After calibration, the proposed model captures the trend of the official confirmed cases before and after the lockdown. We show that the estimated number of cases depends strongly on the initial dates of the local outbreak onset and the number of imported cases before the lockdown. Our estimations indicate that the population has not reached the level of herd immunization necessary to prevent future outbreaks. While the low prevalence, in comparison to mainland Spain, has prevented the saturation of the health system, this low prevalence translates into low immunization rates, therefore facilitating the propagation of new outbreaks that could lead to secondary waves of COVID-19 in the region. These findings warn about scenarios regarding after-lockdown-policies and the risk of second outbreaks, emphasize the need for widespread testing, and could potentially be extrapolated to other insular and continental regions.
2020年3月14日，西班牙政府宣布实施封锁，以应对新冠病毒的快速传播。结果，由于机场和港口关闭，巴利阿里群岛几乎完全与世隔绝，这些隔离措施和居家隔离导致该地区新冠病毒的感染率较低。我们提出了一个新冠病毒传播的分区模型，包括五个分区（易感者、暴露者、症状前感染者、患病者和康复者），以及各市镇之间的流动性。模型参数根据西班牙卫生部提供的确诊病例时间序列进行校准。校准后，所提出的模型捕捉到了封锁前后官方确诊病例的趋势。我们表明，估计的病例数在很大程度上取决于当地疫情爆发的初始日期以及封锁前输入病例的数量。我们的估计表明，该地区人口尚未达到预防未来疫情所需的群体免疫水平。虽然与西班牙大陆相比，较低的感染率避免了医疗系统的饱和，但这种低感染率转化为低免疫率，因此有利于新疫情的传播，可能导致该地区新冠病毒的二次爆发。这些发现警示了封锁后政策的相关情况以及二次爆发的风险，强调了广泛检测的必要性，并有可能推广到其他岛屿和大陆地区。
