Vaccine hesitancy has always been a problem, but with the rise of COVID-19 and its super-contagious variants, it’s never been more crucial to find a solution. That’s why we’ve seen, for example, federal vaccine mandates emerge across the world.

These measures are, to put it mildly, fairly controversial, and some say they’re at best a band-aid. So if we want to solve the problem, we first have to understand what causes it – and a new study, published in the open-access journal BMJ Open, may have discovered one piece of the answer.

“While interrelations between trust in public bodies and compliance with guidance has been studied elsewhere, far less attention has paid to the life-course factors that may contribute to lower trust in health and state systems and potential rejection of related regulations and medical interventions,” the paper explains.

“[Our] results identify individuals with a history of childhood adversity [as] having less trust in NHS COVID-19 information and being more likely to favour removal of control measures.”

The term "adverse childhood experiences", or ACEs, is a scientific euphemism for traumatic experiences as a kid. That can be direct, from things like physical, psychological, or sexual abuse, or neglect; or via “other sources of chronic trauma in childhood,” the authors write, “such as growing up in a household affected by domestic violence, substance use and other criminal justice problems.”

While it’s not by any means a fate set in stone for survivors of ACEs, multiple studies have found correlations between ACEs and later chronic health problems such as cancer, cardiovascular disease, type 2 diabetes, and respiratory diseases, plus what the authors call “health-harming behaviours” – things like smoking, alcohol misuse, and illicit drug use – and lower mental health and ability to trust.

When you add all that up, you find a population that’s particularly vulnerable in the COVID-19 pandemic, the authors explain: “individuals with ACEs may be at greater risks of COVID-19-related morbidity and mortality through higher vulnerability resulting from behaviours such as smoking and conditions such as obesity and diabetes.”

“Consequently, it is important to understand and address any impact of ACEs on compliance with COVID-19 controls in order to avoid repercussions both for the health of those with ACEs and for infection risks in their local communities.”

The team examined responses to an anonymous telephone survey of adults living in Wales between December 2020 and March 2021 – a time when COVID-19 restrictions were in full force. Of the more than 6,700 people originally contacted, there were 2,285 who met all the eligibility criteria and were included in the final analysis.

Just over half of those reported no history of the ACEs listed in the questionnaire. Of the others, around one in five reported experiencing one type of ACE; around one in six reported two or three types; and one in 10 reported four or more.

Those numbers are pretty typical: “Around half of adults in Europe and North America have experienced at least one ACE with estimates suggesting around a quarter have suffered multiple ACEs,” the authors write.

Using statistical analysis techniques, the team discovered what they had hypothesized to be true: exposure to ACEs, and especially four or more ACEs, dramatically increases the number of worrisome pandemic behaviors.

“Lower trust in NHS COVID-19 information tripled between those with no ACEs and those with four or more and feeling unfairly restricted by government more than doubled,” the paper explains.

“Such increases are consistent with other findings here that individuals with four or more ACEs were two times more likely to break restrictions at least occasionally compared with those with no ACEs when controlling for relationships with sociodemographic factors and history of COVID-19 infection or chronic disease.”

While the results are an important addition in the fight against COVID-19, there were a few limitations to the study that are important to note.

As is typical for telephone interviews, the study only had around a 36 percent response rate, and “we do not have any measures of whether responses would have differed in those refusing to participate or not answering calls,” the authors note.

The survey also relied entirely on self-reported ACE memories and pandemic behaviors – respondents “may have either exaggerated, forgotten or chosen not to disclose childhood adversities or compliance with COVID-19 restrictions.”

Women were overrepresented in the sample, while people from ethnic minority backgrounds were underrepresented. And, lest we forget: Correlation Is Not Causation – or in other words, the team showed that ACEs and COVID non-compliance were related somehow, but they did not show that one causes the other.

Nevertheless, the researchers believe that their results have some important implications for public health measures going forward. They point out some good news: mostly, the people surveyed were following and supportive of, COVID-19 restrictions regardless of whether they had experienced ACEs or not.

“Without consideration of how best to engage … individuals [with ACEs], some risk being effectively excluded from population health interventions, remaining at higher risks of infection and posing a potential transmission risk to others,” the authors write.

“Increasing the appeal of public health information and interventions, such as vaccination, to those who have experienced ACEs should be considered in health protection responses.”

“Longer term, however, achieving better compliance with pandemic and other public health advice is another reason to invest in safe and secure childhoods for all children which are free from ACEs and rich in sources of resilience,” they conclude.

“Such measures appear likely not only to reduce health-harming behaviours and ill health across the life-course but may also reduce the spread of COVID-19 or other infectious threats to public health that may materialise in subsequent decades.”