How to estimate the hypothetical benefits of implementing vaccine restrictions?

We encourage you to read the latest article by dr Bartosz Helfer, head of the Scientific Excellence Incubator – Meta Research Center

LINK TO ARTICLE

Dr Bartosz Helfer explains: “During the SARS-CoV-2 pandemic, there has been increased interest in introducing vaccine restrictions, which involve limiting unvaccinated people’s access to restaurants, health care facilities, public transportation, entertainment venues or supermarkets, among others. The idea of the restrictions generally involves isolating unvaccinated people to limit out-of-home transmission of the virus and reduce the number of serious cases. Currently, there is a lack of methods for determining the number of unvaccinated people who need to be isolated to obtain the hypothetical advantages of applying vaccine restrictions. In this paper, we have suggested a procedure for estimating the benefits of vaccine restrictions, using a variant we have developed of the so-called “number needed to treat” (NNT; a popular measure used in clinical medicine that represents the number of individuals that must be intervened upon in order for a desired effect to occur in one person treated over a specified time horizon). We referred to this new variant of the NNT as the “number needed to isolate” (NNI; analogous to NNT – it is the number of people who must be isolated to prevent a single viral transmission event within a specified period of time). We used publicly available data on the SARS-CoV-2 pandemic to demonstrate the properties and utility of the NNI and to make a  meaningful contribution to the debate on vaccine restrictions. We analyzed data from the European Union, the United Kingdom, the United States, Canada, Australia, and Israel from the fall of 2021 when the Delta variant (B.1.617.2) of the SARS-CoV-2 coronavirus was predominant. Some of the regions we examined implemented some form of restrictions to limit coronavirus transmission during this time (e.g., the United Kingdom, some EU countries, Canada, Australia, and Israel). NNI estimates suggest that in many regions, hundreds, and often thousands, of unvaccinated people would need to be prevented from entering various places of public consumption (on a given pandemic day) in order to prevent either one viral transmission event or one case of severe disease. It should be emphasized that these conclusions cannot be generalized to other regions and/or periods of the SARS-CoV-2 pandemic, and we do not know whether this measurement method will be applicable to new conditions or to other infectious diseases. Nevertheless, its potential use in cost-benefit analyses of vaccine restrictions, could in the future contribute to more rational public health decision-making during epidemics.”