In 1904, the Brazilian city of Rio de Janeiro shook with violence as citizens rioted. Property was destroyed, dozens were wounded, and 30 people lost their lives as the population rose up against a perceived common enemy: a mandatory vaccine for smallpox.
To impoverished citizens who already had little trust in government authorities, it was a final straw. The response was extreme, but it serves as a reminder of how much public healthcare relies on winning the 'hearts and minds' of the community.
Public vaccination programs are often a careful balance of carrot versus the stick. We'd all like to feel like we have absolute freedom over our own bodies, but some things are just too risky to leave up to individual discretion.
As vaccine-preventable diseases surge, governments around the world are putting down the carrots and bringing out bigger sticks in the form of mandatory vaccinations. The programs seem to be working, but a recent report points out it isn't without cost.
New Zealand Medical Association researchers Mary Nowlan, Esther Willing, and Nikki Turner have summarised a review of the literature on factors that influence vaccination coverage in New Zealand.
They report that while mandatory programs are marginally effective, they risk further isolating disenfranchised parts of the community, making it even harder to eradicate potential hotspots of disease.
Keeping communicable diseases under control is something of a team effort. When around 95 percent of a population is effectively immune to a pathogen, the chance that the disease will easily spread becomes remote.
Despite this, there are inevitably individuals who can't acquire immunity, due to medical conditions or other factors. Because of this, it's a health authority's job to convince every other individual that it's their responsibility to defend their body through vaccines as much as possible.
There are many ways authorities can do this. Communicating the science and facts on sanitation, hygiene, and immunisation is effective when we trust the source.
Unfortunately, changes in how we communicate have helped create pockets of confusion, misinformation, and most importantly, mistrust.
For sectors of the community dealing with a history of broken trust, the usual public service announcements on immunisation schedules simply won't cut it, the researchers say.
"Vaccination policies that ignore social and ethnic sensitivities risk lacking public support even when they have a strong evidence base," the team writes.
This isn't always as simple as a staunch opposition to vaccinating. Many parents are simply delaying vaccination schedules as life's other challenges take priority.
"Since 2017, inequity in coverage has been increasing especially in timeliness of delivery at the six-month mark, and particularly for children of Māori ethnicity and children living with socioeconomic deprivation."
With opposition to vaccines on the rise and the usual communication measures failing, governments are increasingly turning to fines or other punitive measures to push vaccination rates back up.
A choice between a jab and a fine is enough to motivate many parents into visiting their nearest medical clinic.
That might nudge up the vaccination rates, but it might not be enough to hit the golden 95 percent mark across all demographics that keeps pathogens at bay. And for some community sectors, perceptions of autonomy and equity make all the difference when it comes to acting.
For those facing money challenges, a financial penalty could lose its impact. If they're unable to pay the fine, there's not only less incentive to vaccinate, there's added animosity and mistrust.
"Accumulative and negative effect on the family's wellbeing could lead to further hardship and social exclusion," the researchers write.
Mandatory vaccinations also cost a lot in resources, chasing up penalties often for little gain.
If facts and fines won't move people, though, what will? The researchers emphasise the importance of having healthcare workers who identify with a community and are able to build trust.
"Vaccination advocates with similar backgrounds to the target population can help to increase trust and acceptance," they write.
There's no simple, one-size-fits-all solution when it comes to convincing parents to immunise their families.
Vaccination is an emotional topic that polarises populations – but when the consequences are a matter of life and death, sometimes we need to ditch the stick and hold out a hand instead.
This research will be published in the New Zealand Medical Journal.