We should not dismiss the possibility of eradicating COVID-19: comparisons with smallpox and polio

Elimination and eradication of disease are among the ultimate goals of public health1 (for definitions see box 1). Vaccination has globally eradicated smallpox, rinderpest (a cattle disease that caused famines2) and two of the three serotypes of poliovirus.3 Three other vaccine-preventable diseases are eradicable globally with current technology,4 with measles the leading contender and with MMR vaccination potentially eradicating mumps and rubella at the same time. Some other diseases are close to being eradicated but without use of vaccines such as with the Guinea Worm Eradication Programme.5 Similarly, China has recently eliminated malaria with a range of non-vaccination tools, to become the 40th country to be certified malaria-free.6 Box 1 Definitions of key disease control terms from the Dahlem Workshop19 Control: The reduction of disease incidence, prevalence, morbidity or mortality to a locally acceptable level as a result of deliberate efforts; continued intervention measures are required to maintain the reduction. Example: diarrhoeal diseases. Elimination of disease: Reduction to zero of the incidence of a specified disease in a defined geographical area as a result of deliberate efforts; continued intervention measures are required. Example: neonatal tetanus. Elimination of infections: Reduction to zero of the incidence of infection caused by a specific agent in a defined geographical area as a result of deliberate efforts; continued measures to prevent re-establishment of transmission are required. Example: measles, poliomyelitis. Eradication: Permanent reduction to zero of the worldwide incidence of infection caused by a specific agent as a result of deliberate efforts; intervention measures are no longer needed. Example: smallpox. Extinction: The specific infectious agent no longer exists in nature or in the laboratory. Example: none. Is COVID-19 also potentially eradicable? Or is it inevitably endemic having established itself across the world? Commentators have focused on the challenges of reaching population (herd) immunity,7 yet population immunity is not essential and was not achieved for smallpox, which was eradicated through ring vaccination. As proof of concept for COVID-19 eradication, several countries and jurisdictions have achieved elimination without vaccination, using new and established public health and social measures (PHSMs) (eg, border control, physical distancing, mask wearing, testing and contact tracing supported by genome sequencing).8 Successful jurisdictions have included those with vast land borders such as China, high population densities such as Hong Kong,9 but also island nations such as Iceland and New Zealand, although with occasional outbreaks from border control failures that have been brought under control.10