Model agentowy ruchów antyszczepionkowych: symulacje i porównanie z danymi empirycznymi(*)  
[Agent-based model of anti-vaccination movements: simulations and comparison with empirical data]

Paweł Sobkowicz (NOMATEN Centre of Excellence, National Centre for Nuclear Research, Świerk)	


A realistic description of the social processes leading to the increasing reluctance to various 
vaccination forms is a very challenging task. This is due to the complexity of the 
psychological and social mechanisms determining the individual and group positioning versus 
vaccination and the associated activities.

Due to the role played by social media and the Internet in the current spread of the 
anti-vaccination (AV) movement understanding the use of the infosphere is of significant 
importance. We present novel Big Data analyses of the Internet activity connected with the AV 
movement for such different societies as the US and Poland. The datasets we analyzed cover 
multiyear periods preceding the COVID-19 pandemic, documenting the growth of the current wave 
of the AV sentiments. Significant similarities between the observed user activity, with 
strongly nonlinear effects present.

Complementing the empirical observations, we propose an Agent Based Model (ABM) of the 
anti-vaccination (AV) movement, which includes the interplay between contacts with medical 
practitioners, societal communication and the influence of the infosphere (social networks, WEB 
pages, user comments etc.), as well as the difference between the rational approach of the 
pro-vaccination information providers and emotional appeal of the anti-vaccination propaganda. 
One of the surprising results of the model is that the temporal behavior of the support for the 
anti-vaccination movement is not monotonous but shows a presence of spiky attention cycles. For 
a range of parameters, the simulations result in a relatively small fraction of people refusing 
vaccination, but a slight change of the critical parameters (such as the willingness to post 
anti-vaccination information) may lead to a catastrophic breakdown of vaccination support. The  
results validate the proposed model mechanisms and assumptions, allowing significant progress 
in the understanding of the vaccination reluctance and opposition in the pre-COVID era.

The model could potentially allow for studying potential strategies combating the 
anti-vaccination movement. The increase of intensity of standard pro-vaccination communications 
by the government agencies and medical personnel is found to have little effect. On the other 
hand, focused campaigns using the Internet and social media and copying the highly emotional 
and narrative-focused format used by the anti-vaccination activists can diminish the AV 
influence. The benefit of such tactics might, however, be offset by the social cost of such 
measures, for example, the increased polarization and potential to exploit it for political 
goals. 


(*) joint work with Antoni Sobkowicz (National Information Processing Institute OPI)