Once upon a time there was a distant island with beautiful beaches, where swimming was the most popular sport. Everyone loved to swim, but there was a problem: some beaches were very rough, and many people drowned. The king (the republic had not yet been proclaimed in this world of allegories) was concerned, and decided to institute a public health measure: the State would provide life vests at the entrance to the beaches. Many accepted the vests; others did not. The king was pleased that the life vests appeared to contribute toward a reduction in drownings. The laws of physics were on the side of the vests. Animal models showed that the vests helped mice to stay afloat. On some beaches, observational studies also demonstrated the effectiveness of vests. Even randomised studies were conducted, to compare the people with vests to those without, and they showed very positive results.
This went on until a group of scientists published a review that pooled all the available studies, and the review indicated that the provision of vests hadn’t actually reduced the overall number of drownings. The researchers explained that it was not about using a life vest as an individual piece of equipment, but rather that it was about people’s behaviour. There were some who failed to inflate the life vest. Some even accepted the vest, but then removed it in the water, because they found it uncomfortable. Yet others were emboldened by the perceived safety provided by the vest, and eventually they began to take risks. The scientists concluded that use of life vests in the community did not reduce the drowning mortality rate.
The king was very angry. He accused the scientists of being crazy. Disgruntled, he decided to create the life vest police. Now, the life vest was mandatory. “Without one, you cannot enter the beach”, went the decree.
The people were infuriated, and became divided on the issue. On one side, there were those who were pro–life vest, and wore it all the time, even indoors. On the other, there were those who wore a vest to go to the beach — after all, it was mandatory — but took it off when they went into the water, or they deflated it, just to be contrary. Some even tied theirs to their feet in protest. And so, the drowning deaths continued.
The kingdom’s newspaper reported that people had died, even when wearing a life vest. The op-ed pages were ablaze. “What good is a life vest? What about the girl who never wore a vest and swam ten miles a day? Using a vest is an over-reaction; it’s for those who can’t swim!” Polarisation grew, and the drowning mortality rates remained unchanged. Nothing had been achieved by instituting the life vest rule.
So the king decided to change his strategy. He eventually heeded the counsel of behavioural psychologists and experts on science communication, and mounted a huge campaign designed to educate people on how the life vest worked, and where and why it should be worn. There was no need to use it on all beaches, or indoors. It wouldn’t do any good to use it deflated. It was meant to be worn on the torso, not to be tied to one’s foot. The life vest is not magic, if you swim in very dangerous waters, you’ll still be at risk. The king relaxed his mandate and created incentives: whoever left the ocean wearing a life vest correctly would be given a voucher for a popsicle. He made a deal with scientists to design a new study, to be conducted after the educational campaign.
Alas, it was already too late. The anti-vest group decided it was all a conspiracy, and ignored the new campaigns. They spread the rumour that the free popsicles contained poisonous ingredients, and that the “pro-vest” scientists were all in the pockets of the life vest industry. “People die all the time; it’s part of life, even more so in a kingdom by the sea.”
The effectiveness of any public health intervention, whether one involving vaccines, masks, or allegorical life vests, crucially depends on its being understood and accepted by the public, and on public behaviour, regardless of the intervention’s biological plausibility or its effectiveness in controlled clinical trials.
When new studies force us to contemplate the possibility that measures which seem correct are not showing the expected practical results, we must humbly face reality and review our strategies. When the health of the community is at stake, making it work is far more important than insisting on being right.
The whole masking or vaccine effectiveness debate tells us more about our skills in communicating science, especially when it comes to explaining risk and probability, than it says about masking trials, or vaccine trials. If there is a take home message from all this nonsense about what the Cochrane metanalysis “really says”, it is that we have to invest heavily in science and risk communication as essential tools for pandemic preparedness.
We must be able to communicate about uncertainty, with honesty and transparency, explaining what we know, and what we still don’t know, and how and why we are making decisions based on the available evidence. Most countries implemented mask and vaccine mandates with very little effort, and without campaigns to explain how they work. Countless people wore masks outdoors, or indoors but with their noses sticking out, or took them off to talk. A great number of people seemed to think that masks were magic, and thus didn’t need to avoid crowded and enclosed spaces. A great number of policy makers seemed to think that masks were magic, and thus measures to improve ventilation in school premises, and to reduce rush hours on public transportation, were deemed unnecessary.
The same happened with vaccine mandates and explaining vaccine efficacy. Many people expected the vaccines – any vaccine – to protect them magically, so when people who were vaccinated got the disease, they assumed that the vaccine doesn’t work, and that they had been fooled.
During my deposition at the Brazilian Senate, when I was asked as an expert witness in science communication, I used another analogy, not much different from the life vests, to explain risk and probability: the goalkeeper analogy. A good vaccine is like a good goalkeeper, who will save most shots, but not every shot. Even the best goalkeeper will concede a goal from time to time, because they are not infallible. And if the team’s defence is bad, there will be far more shots coming in the goalkeeper’s direction, making it even more probable that a goal is going to be conceded.
Similarly, if society’s “defence” is bad – if people refuse vaccination, refuse to wear a mask or to engage in protective measures – there will be a lot more of the virus circulating, making it more probable that people will get the disease, even if they are personally taking precautions. The goalkeeper is not magic, and neither is the vaccine. Or the masks. Or the life vests. It all depends on how well they are adopted by society.
The analogies are from perfect, of course. Life vests are meant to protect the person wearing them, whereas masks protect people around us. Goalkeepers usually receive one ball at a time, and vaccines protect us from various amounts or viral loads. But analogies give us an idea of how to assess risk and probability, and more importantly, they take us away from that preconceived version of science, where everything has a right or wrong answer. Science is built on uncertainty and probability. Anyone trying to sell you certainty and 100% answers is most likely engaging in pseudoscience and conspiracy theories. Expecting vaccines to work 100% with no side effects is an almost impossible expectation, as much as expecting a goalkeeper to be invincible.
Scientists need training to speak to the public and to policy makers, and policy makers need training to understand scientific method and processes, and to communicate science to their constituents. If we don’t start taking science communication seriously, we won’t be any better prepared for the next health emergency.
The life vest analogy in this article was translated from the original Portuguese by Ricardo Borges Costa, and first appeared in O Globo newspaper.
