Once Understood As The Sum Of Elite Fears - The Great Reset Is Here To Stay

voxeu |  One great unknown about COVID-19 is whether individuals who recover from it can be reinfected. At the emergence of any new virus, it is impossible to know whether immunity is permanent or wanes, until enough time has passed for longitudinal studies to take place. At the moment, and with limited available data, medical scientists and epidemiologists are instead comparing SARS-CoV-2 to related coronaviruses, such as HCoV-HKU1 and HCoV-OC43, which are known to exhibit waning immunity. An early contribution by Kissler et al. (2020) assumed that immunity to SARS-CoV-2 wanes in approximately 45 weeks. A recent medical study (Long et al. 2020) found a significant drop in specific antibody levels after three months. Nevertheless, the duration of immunity in general is still far from understood. 

In Giannitsarou et al. (2020), we explicitly consider a setting in which immunity is temporary. We derive a stylised optimal containment policy and contrast it to policies assuming that once recovered, individuals are forever immune. 

We work with a flexible epidemic model known as SEIRS (Susceptible-Exposed-Infected-Recovered-Susceptible). The model allows for natural births and deaths, disease induced deaths, a pre-symptomatic state in which individuals are exposed to the virus and can be infectious without exhibiting symptoms, and importantly, waning immunity.  In such a framework, because immunity may slowly disappear from recovered people, there is the potential for a second (and even third) wave of infection.

In summary, we find that if immunity to SARS-CoV-2 is temporary, the disease will become endemic. The optimal policy will make an initial effort to reduce the first great infection wave and then engage in a permanent low level management of the persistent infection in the population in order to keep it under control. In practice, this means that partial lockdown or social distancing measures may become the norm for some years to come. 

Our analysis assumed that, currently, the only policies at our disposal are broad-based non-medical interventions such as social distancing and lockdown measures. At the initial stages of the COVID-19 pandemic, such policies proved to be extremely costly from social, economic, and health care perspectives. But going forward, we expect that individuals, businesses, and governments are likely to adapt how they do things and operate to mitigate the costs of this initial dramatic shock. People may become more cautious in everyday dealings, businesses may come to depend less on third parties or off-shoring, while other organisations such as schools, transport, intermediate goods producers, and local governments may find innovative ways to become more flexible and resilient in the ways they deliver services and products. We hope that with creativity and resourcefulness, humanity will learn to navigate and live with the disease, should it turn out to be here for the long term.