A new study conducted by the researchers from Dartmouth College explains why a lot of people refused to get vaccinated despite evidence showing it is safe and beneficial. Researchers said past problems likely created a negative impact on people's perception towards vaccines, causing a phenomenon called as hysteresis. The study was published in the Proceedings of the Royal Society B journal.
According to Phys.org, hysteresis is a phenomenon where the value of a physical property lags behind changes in the effect causing it. For instance, it's like unemployment rates remain high due to a recovering economy, or when magnetic induction lags behind the magnetizing force. Dartmouth researchers explain this is likely the reason why the public contradicts vaccination campaign for common illness, such as flu.
Feng Fu, who is an assistant professor of mathematics at Dartmouth College, said that even though vaccines have a lot of benefits, it's challenging to understand why vaccination rates remain significantly low. Fu, who is also the leader of the research team, noted that when people started questioning the safety and effectiveness of a vaccine, then it will be difficult to inform them regarding the benefits it can provide.
Low vaccine compliance is considered a public health issue because it can cause loss of herd immunity, leading to the spread of infectious diseases. In parts of North America and Europe, childhood diseases such as pertussis, measles, and mumps, have returned due to insufficient vaccination coverage.
The research team studied the past problems linked to vaccinations to understand how it would change the present and future vaccination decisions. Their findings revealed the hysteresis loop was caused by questions regarding the effectiveness and risk of vaccines. Negative perceptions and experiences linked to vaccination also created an impact on the trend of uptake over time, which is called vaccination trajectory.
"This study shows why it is so hard to reverse low or declining vaccine levels," said Xingru Chen, the first author of the research paper and a graduate student at Dartmouth.
Hysteresis is preventing vaccination levels to increase although negative perceptions have been cleared, causing the society to be vulnerable to disease outbreaks. Fu said the past predicts the future of vaccination levels, and unfortunately, some people suffered because of lack of awareness.
Researchers hope that recognizing the hysteresis effect in vaccination could prompt public health officials to implement campaigns to increase voluntary vaccination rates, especially promoting vaccination as an altruistic behavior that is desired by social and moral norms.
