Imperfect

The Covid-19 vaccines are incredibly effective, but not perfect. Keith Lynch explores how this lack of certainty can scramble the human brain.

American NFL player Aaron Rodgers explained why he had not been vaccinated, saying: ‘‘If the vaccine is so great, then how come people are still getting Covid and spreading Covid and, unfortunately, dying from Covid?’’

Rodgers also claimed an NFL doctor said it’s impossible for a vaccinated person to get or spread Covid. The NFL has denied this.

This is a very common refrain. The vaccines are not perfect, therefore what’s the point of getting vaccinated?

Immunologists have wrestled with the challenges of communicating the benefits of ‘‘partially effective’’ vaccines for some time, Dr Fran Priddy, clinical Director of Vaccine Alliance Aotearoa New Zealand said.

It’s, of course, correct that two doses of the Pfizer vaccine don’t offer total protection, and that protection wanes over time. A person can catch Covid-19 if they are vaccinated. They can pass it on. They can still die. But the evidence is very clear: the likelihood of any of this eventuating post immunisation is significantly reduced.

Yet for a cohort of people, ‘‘exceedingly good at stopping serious illness and death’’ and ‘‘very good at stopping infection’’ is not good enough. The imperfection of the Pfizer vaccine has helped nurture vaccine hesitancy.

Ambiguities are inherent in an awful lot of conversations about health. And uncertainties are a stone-cold guarantee when a novel, or new, coronavirus runs rampant in an unprecedented and terrifying manner. Once it seemed the pandemic would end one way, and then Delta came along.

So, what is it about imperfections and uncertainties that scramble the human brain? Why is it, for some, that vaccine imperfection is analogous with ineffectiveness?

Remind me how we started talking about the vaccines

In mid-November last year Pfizer announced how effective its vaccine was at preventing Covid-19. That number was extraordinary: the vaccine prevented 95 per cent of symptomatic cases in the clinical trial. The vaccine, as US medical news website Stat put it, ‘‘flirted with perfection’’. Pfizer CEO Albert Bourla said when he heard the over 90 per cent efficacy following the clinical trials, ‘‘I felt I was living a dream’’.

At that time, the reduction in risk in people getting Covid – it was called efficacy during the trials – was the key descriptor of performance and what most media focused on. The reason for this was quite simple: it was what the early clinical trials studied.

All of this was perfectly reasonable. A study to measure relatively uncommon outcomes like people dying or going to hospital would have been significantly more challenging, US publication Vox explained in a piece titled: ‘‘We’re not looking at the most important statistic’’.

In the Phase 3 vaccine trials, Pfizer enrolled 43,661 people and essentially waited to see how many symptomatic infections occurred in two groups. Of 170 who tested positive for symptomatic Covid-19, 162 were in the group of people given the placebo and only eight were given the vaccine.

To study death and hospitalisations, which are relatively rare, you’d simply need a lot more participants. (That’s not to say Pfizer did not keep an eye on hospitalisations or deaths. It did, and the results were excellent.)

It’s also worth considering that while good clinical trials will do what they can to reflect what will happen in the real world, there are always imperfections, and it may be that results aren’t necessarily replicated precisely in real life.

What’s changed?

We now know the Pfizer vaccine’s effectiveness at stopping transmission wanes over time. One study found its effectiveness against infections declined from 88 per cent during the first month after full vaccination to 47 per cent after five months. Another study (supported by Pfizer) found a gradual decline in efficacy – hence vaccine boosters.

Keep in mind though that studies and real world data show two doses are remarkably good at preventing death and serious illness. A UK analysis focused on the Delta variant found, for example, the Pfizer-BioNTech vaccine is 96 per cent effective against hospitalisation after two doses.

That first study also looked at waning effectiveness against hospitalisation. It found vaccines held up against serious infection for a longer period. (But there have been reports in Israel suggesting ‘‘some reduction in effectiveness against hospital admissions has been observed among older people’’.)

There’s also been a decoupling of case numbers and deaths in the UK, where case numbers have remained high but, in a highly vaccinated population, deaths have not followed.

They’re not perfect then?

Yes, you’d be right to point out that 47 per cent effectiveness against infection six months on is not 100 per cent for all time. You’d also be right to point out that a potential drop off in the vaccine’s effectiveness against severe illness in older people is concerning.

Another recent study, which has been cited by some to discredit the vaccines, also found ‘‘fully vaccinated individuals with breakthrough infections have peak viral load similar to unvaccinated cases and can efficiently transmit infection in household settings’’.

But this doesn’t mean the vaccines are useless – far from it. As that study explains, the vaccine reduces the risk of an infection in the first place, and accelerates how quickly that viral load disappears.

The reality is, talking about vaccines is messy – as is anything when imperfection leaks in.

You, for example, may well think the traffic light system is much messier than the alert level system. That’s perfectly reasonable but remember the alert level system was created to achieve a binary or ‘‘perfect’’ goal: no Covid.

An alternative that allows some Covid is obviously going to be much less elegant.

With that in mind, it’s very easy to see how such an array of information is incredibly dizzying, particularly when the Pfizer vaccine was initially said to be ‘‘flirting with perfection’’.

What we have, in a nutshell, are excellent vaccines that hugely reduce the risk of serious illness and death. But they are not perfect.

Why do we struggle with uncertainty?

Some people equate vaccine imperfection with pointlessness, Priddy suggests, because there are plenty of vaccines administered to children that are almost entirely effective and last pretty much for life; the measles inoculation, for instance. ‘‘So that shapes peoples’ perceptions of vaccines – either they work or they don’t.’’

(Remember, Priddy notes, that the vast majority of people have accepted these ‘‘imperfect’’ but excellent vaccines.)

And it may be that the early reporting on efficacy was unintentionally counterproductive. There’s no reason to doubt the efficacy results in November last year, but we’re in uncharted waters and things

‘‘This might explain why some people are more vocal about the vaccine’s limitations now, given that some people had such high hopes for it being close to perfect.’’ Dr Amanda Wallis

change. Most importantly, the public did not know the incredibly infectious Delta variant was around the corner. And it may well be that three, not two, jabs was always the optimal dosage.

Dr Amanda Wallis, a research lead at Umbrella, suggests that if people expected perfection from a vaccine, some may well be less trustful and therefore less likely to get vaccinated when new information comes to light.

‘‘This might explain why some people are more vocal about the vaccine’s limitations now, given that some people had such high hopes for it being close to perfect.’’

Dr Olivia Wills, a behavioural economist at the New Zealand Institute of Economic Research (NZIER), agrees. ‘‘Given that other familiar vaccines work by completely stopping the disease (for example, measles and smallpox), it’s easy for us to ‘anchor’ on to the idea and expect it from the Covid vaccine too. We rely on mental shortcuts like anchoring all the time, but even more in times of stress or uncertainty.

‘‘This anchor sets up an expectation of perfection... which the vaccine has not been able to keep up with as the virus mutated. Despite overwhelming evidence for reductions in hospitalisation and death, we can feel this failure to meet expectations as a loss, and it can amplify other existing concerns around the vaccine.’’

Other psychologists at Umbrella explained why the human mind struggles with uncertainty.

The intolerance for ‘‘imperfection’’ in the vaccines may be related to a broader ‘‘intolerance of uncertainty’’, a common feature of anxiety, which is when people struggle with the idea that nothing in life is certain or perfect. When things are uncertain and that uncertainty makes us anxious or uncomfortable (for example, ‘‘I could get vaccinated and still get Covid’’), our mind comes up with reasons as to why we can’t, or shouldn’t have to engage with the uncertainty (‘‘the vaccine isn’t perfect, therefore it’s not worth getting’’). And, finally, when uncertainty strikes, another common reaction is that people often go and search for more information in the mistaken belief that information is the path to certainty. The short term benefit would be a reduction in anxiety, but long term it creates more uncertainty/anxiety because you just can’t get 100 per cent certainty in an uncertain world. This can fuel a vicious cycle.

If we discussed uncertainty all the time wouldn’t that just confuse people?

Maybe. Or maybe not. A recent UK paper, that is yet to be peerreviewed, explored the ‘‘negative consequences of failing to communicate uncertainties’’ when it comes to Covid-19 vaccines.

It notes that earlier study found there may be ‘‘advantages to not communicating uncertainties’’ but asked what happens if people are told something and then things change? ‘‘When uncertainties do exist, can ignoring them backfire and eventually lead to worse outcomes?’’

To do this, the study’s participants were told to imagine a public health expert making a vaccine announcement.

A first group was told: ‘‘I can confirm that the vaccine is 60 per cent effective. This means that, although the vaccine might not work for everyone, there is a very good chance that it will work for you. This vaccine will significantly drive down the infection rate and we will be able to remove the restrictive measures we put in place to combat the virus.’’

The second was told: ‘‘The vaccine is between 50 and 70 per cent effective. The reason I can’t give a more precise estimate is because the data we have doesn’t allow that. There might be some things we don’t know yet about the vaccine, but this is the best available option. Although it might not work for everyone, there is a chance it will work for you. This vaccine will hopefully drive down the infection rate and we may be able to remove the restrictive measures we put in place to combat the virus.’’

Then a week later everyone was told new research had emerged showing the vaccine is actually closer to 40 per cent effective.

The researchers thought the people who were told the vaccines were definitely 60 per cent effective were likely to get upset when that new information came to light and the study found just that – the people who were given certainties were less likely to get vaccinated following the new information.

While noting limitations with the study, the authors said the findings support calls for greater ‘‘acknowledgements of uncertainty in communications relating to Covid-19’’.

In a separate piece for British magazine The Psychologist, Eleonore Batteux, one of the authors, suggested people want to believe the future is predictable. The alternative is uncertainty and therefore worry. What follows, she writes, is that politicians communicate with certainty because that’s what people want.

The same appears to be true here, former National government press secretary Ben Thomas told me. While complexity and uncertainty is baked into New Zealand politics, politicians still prefer to communicate in a manner that’s punchy, digestible and certain.

Politicians, Thomas says, like to portray a sense of being in control. And the public generally wants to view every issue – even Covid-19 – as being solvable by the Beehive.

Most of the time our political leaders can navigate through uncertainty. They can, for example, just pass a law (problem solved) or introduce a policy and explain it away when it doesn’t work out.

But the pandemic is very different. For instance, when Delta arrived, the Prime Minister Jacinda Ardern said she wanted a sharp and short lockdown for Auckland. Days earlier, before we even knew of Covid’s infiltration she said New Zealand would be sticking with elimination.

The government had nothing to do with the emergence of the incredibly infectious Delta variant, which has radically changed the dynamics of this pandemic. It’s certainly not its fault the vaccines’ effectiveness wanes somewhat.

All of this uncertainty, however, makes effective communication incredibly challenging.

And it’s not only politicians. Traditional media reporting styles in New Zealand aren’t necessarily always the best format to acknowledge there are very few guarantees with Covid-19.

So what does all this mean then? Well, uncertainty is an inescapable fundamental of the pandemic. But that uncertainty doesn’t mean our response – particularly vaccination – is futile.

Think of it this way, Priddy suggests. ‘‘Seat belts reduce your risk of death or injury but aren’t perfect. Or maybe tooth brushing – it definitely reduces your risk of things like cavities, gum disease and bad breath, but it’s not 100 per cent effective.’’ Does any of this mean seat belts and toothbrushes are pointless?

Anything else?

Recently four former Aviation Security Service employees challenged a public health order requiring them to be vaccinated.

As part of the case, epidemiologist Dr Simon Thornley, suggested among other things that the Pfizer vaccine is ineffective at stopping transmission of the Delta variant

You can read the full judgement at www.courtsofnz.govt.nz, but the conclusion from Justice Francis Cooke, who considered the evidence, is definitive.

‘‘I do not accept the applicants’ challenge that the vaccine is experimental, unproven, unsafe and that it has little effect on transmission. I am satisfied that the vaccine is safe and effective, is significantly beneficial in preventing symptomatic infection of Covid-19 including the Delta variant, and that it significantly reduces serious illness, hospitalisation and death.’’

There was also evidence presented during the case about the possibility of asymptomatic spread of disease in highly vaccinated countries contributing to high case numbers.

Justice Cooke’s response is quite telling: ‘‘Such possibilities do not mean that vaccination does not inhibit transmission. It just means there are uncertainties.’’