Nonpharmaceutical Interventions (NPIs) are actions that can slow the spread of contagious illnesses such as viral infections, and that are apart from pharmaceutical interventions (PHIs) which include taking vaccines or medicine. NPIs include social distancing, quarantine, isolation, school and workplace closure and travel restrictions. NPIs may reduce opportunities for contact between people through physical barriers or masks.
Using NPIs can ease pressure on health service providers until vaccines and antivirals are developed and distributed or in situations where vaccines or resources needed to administer vaccines are not available. Mathematical modeling is used to understand the potential impact of different NPI measures and help inform that adoption of policies.
Personal NPIs include staying home when you are sick, covering coughs and sneezes with a tissue and washing hands or using hand sanitizer. Community NPIs are policies and strategies that organizations and communities put in place, such as social distancing rules and closure of areas where groups of people gather. Environmental NPIs include routine cleaning of surfaces that are frequently touched such as desks, door knobs and toys in homes, schools, workplaces and other settings where people gather in numbers.
NPI strategies may aim for suppression, which is to reduce the reproduction number (R), the average number of secondary cases each case generates, to below 1. The main challenge for suppression is the maintenance of NPIs for as long as the virus is circulating in the human population or until a vaccine is available. NPI strategies may be used for mitigation, which is the reduction of health impact of the epidemic, without completely interrupting transmission of the virus. With the aim of mitigation, population immunity builds during the epidemic and leads to an eventual decline in transmission and case numbers.
