Vaccination, community service, and Rose’s Paradox

Covid vaccination is a controversial topic that I don’t want to venture into. Here, I would like to argue that when you decide to have a jab, it means that you do a community service.

Many Australians (perhaps up to 30%) are reluctant to take a jab for Covid-19 [1]. They argue that there is a lack of safety data concerning the existing vaccines (which can take years), and that they will benefit little from the vaccination. Here, I want to discuss the second point by invoking a famous epidemiological theorem called ‘Rose’s Paradox’, and urge that they should have a jab if possible.

Geoffrey Rose (1926–1993), CBE, is one of my academic heroes. He was a Professor of Epidemiology at the London School of Hygiene and Tropical Medicine. He is the author of the famous book, ‘The Strategy of Preventive Medicine’, which has been one of my bed reading books. The book is actually an extended version of his seminal paper titled ‘Sick individuals and sick populations’ (available free in Int J Epidemiol). I came across the book during my PhD study, and I was so enlightened by the ideas presented in the book that I have subsequently applied those ideas in my osteoporosis research.

So, what is his idea that I am talking about here? In a nutshell, Rose postulated that a public health intervention that brings little benefit to an individual can yield large benefits to the community [1]. This paradox can be seen easily by considering the case of wearing car seatbelt. Now, seatbelt is designed to reduce the injury and death caused by an accident, but the probability of accident is very low relative to the number of cars on the road at any time point. That means, most of drivers and passengers don’t have accident in their lifetime, and wearing seatbelt brings very little benefit to the wearer. However, we know that seatbelt does save many many lives in the community.

The same thinking can also be applied to Covid vaccination reasoning. We know that at the individual level the risk of being infected by SARS-Cov-2 is very low (i.e., perhaps well below 1%). So, vaccination is expected to bring very small benefit to each of us, because most of us will not be infected anyway. However, if all of us in the community get vaccinated, then the number of infected cases and the number of deaths…