What's the most effective way to roll out the COVID-19 vaccine?
Researchers argue that prioritising vaccination of 鈥榮uperspreaders鈥� could contain COVID-19 faster. Credit: Pixabay.
The level of vaccination uptake will be the most important factor in controlling the COVID-19 pandemic, according to a new position paper by an international consortium of scientists which compared COVID-19 vaccination strategies.
罢丑别听聽鈥� authored by scientists and health experts from the University of Sydney鈥檚 Centre for Complex Systems and the Faculty of Medicine and Health in collaboration with scientists and epidemiologists from India and Europe 鈥� emphasises that, given the limited availability of vaccines at the initial stage of the COVID-19 vaccination rollout, effective prioritisation and optimal use of vaccination resources will be crucial to contain the pandemic in the near future.
鈥淚t is not desirable to expose a significant portion of the population to the pathogen in order to acquire herd immunity,鈥� said lead author, 顿谤听Mahendra Piraveenan聽who is a senior lecturer in complex systems in the聽Faculty of Engineering.听
鈥淚nstead we should aim to achieve herd immunity through vaccination to minimise morbidity and mortality. But if we get the prioritisation right, we might be able to vaccinate people who are 鈥榮uperspreaders鈥� first, so that herd immunity can potentially be reached with less than 60 percent of people vaccinated, which is the often-quoted approximate threshold calculated based on the basic reproduction number R0.鈥�
The researchers argue that vaccines which target transmissibility should be given to 鈥榮uperspreaders鈥� first 鈥� people who are more likely to transmit the virus to many people 鈥� while vaccines that reduce symptoms and severity of the disease should be given to more vulnerable groups.
Co-author, 顿谤听Shailendra Sawleshwarkar, clinical academic from the Westmead Clinical School and the Faculty of Medicine and Health, said: 鈥淚f the vaccine reduces the transmissibility of the SARS-CoV-2 virus, then vaccination prioritisation should be based on individuals, cities or states that act as 鈥榮uperspreaders鈥�.鈥�
鈥淏ut if the vaccine is the type that reduces symptoms, severity of disease, or mortality, prioritisation should be based on targeting individuals, cities, or states that are likely to have poorer outcomes if infected."
顿谤听Michael Walsh, infectious disease epidemiologist and senior lecturer at the University of Sydney鈥檚 School of Public Health said: "vaccination efficacy is important, but high efficacy will not remove the need for high uptake. Indeed, some forms of suboptimal delivery and uptake, such as reducing the dosing schedule for some vaccines, could reduce a vaccine鈥檚 efficacy. The effective distribution of vaccines and the percentage of people who take those vaccines will essentially determine our success against COVID-19.鈥�
Using "game theory" to model the vaccine rollout
The paper is currently under peer review but has been made聽聽through preprint server,聽arXiv聽due to the urgency of the COVID-19 pandemic. It also proposes that game theory coupled with simulation modelling should be used to model different vaccination uptake scenarios. In turn, these models can be used to guide policymaking in relation to the vaccine rollout.
Game theory refers to the use of mathematics to model rational decision-making by individuals or groups with competing interests.听
鈥淕iven that vaccination policy decisions are often difficult to arrive at, it is absolutely vital that our policymakers get them right. We propose game theory, supplemented by social network analysis and agent-based modelling, to model and analyse various vaccine scenarios,鈥� Dr Piraveenan said.
鈥淕ame theory is ideally suited to model vaccination uptake because it can model both 鈥榩ush鈥� and 鈥榩ull鈥� decisions 鈥� decisions by policymakers about who should be prioritised, and decision making by individuals whether to take vaccine.
鈥淔or example, a person鈥檚 age, gender, education and clinical history may determine whether they would voluntarily take a vaccine. People who perceive they are at higher risk might have more incentive to voluntarily get vaccinated.
鈥淚t will be important to model individual decision-making patterns, so that community level vaccination outcomes can be achieved. For example, if the government has a target of vaccinating four million people by the end of March, it will be important to offer the vaccine to demographics who will have high voluntary uptake so that we don鈥檛 fall behind this goal.鈥�
DECLARATION
No funding or conflicts of interest to declare.
