Anti-vaccine activists will weaponise AstraZeneca suspension

Even quick reversal of decision to suspend vaccine may not be enough to change public perception

The slow but steady rollout of vaccines for Covid-19 across Ireland has led to renewed optimism about the future. The announcement on Sunday that the administering of one of the vaccines would be suspended pending a safety investigation has dented this optimism.

The impetus for this decision was reports from Scandinavia of 30 serious blood clot events following the administering of five million doses of the vaccine in question which is manufactured by AstraZeneca, the British-Swedish multinational pharmaceutical company.

So is the vaccine safe? To answer that, we can look at the data from trials conducted on the vaccine before it was approved by the European Medicines Agency and other regulators. They showed an excellent safety profile and no evidence of induced blood clotting. And despite the current concerns, emerging data does not conclusively suggest any increase in clotting risk either.

Total doses distributed to Ireland Total doses administered in Ireland
9,452,860 7,856,558

Hospital Report

For example pulmonary embolisms – blot clots in the lungs – afflict about 1 person in 1,000 per year. In a population of five million people, we would expect 5,000 to have an episode within a year – just under 14 people a day. For this reason, 30 reported cases following five million vaccinations is in line with what could be expected and not indicative of elevated risk.


In the United Kingdom, where more than 11 million doses of the vaccine have been given, vaccinated cohorts have not seen an increase in thrombotic events. Nor does any signal of harm emerge from data on over 17 million doses given in the UK and EU, leading the WHO to reiterate on Friday that countries should not stop using it.

Abundance of caution

This advice has not been heeded by several countries – including Ireland – who have deferred vaccination out of an abundance of caution. But while caution is admirable, it must be based on evidence in totality. Hypothetical vaccine harms must be contrasted with the very real harms of Covid-19. The precautionary principle is often invoked in these circumstances but it is too often forgotten there is a cost of inertia.

The advent of Covid-19 vaccines has seen a staggering rise in targeted disinformation and conspiracy theories propagated about the vaccine

Suspending administration of the AstraZeneca vaccine is not a zero-risk option. This week alone it has led to the cancellation of 30,000 vaccine appointments in Ireland. The risks and benefits must be carefully weighed. While the contention that the AstraZeneca vaccine causes clots is contestable, we have strong evidence that Covid-19 itself drastically increases clot risk. The precautionary principle is well-intentioned but it is no substitute for evidence-based decision making.

But perhaps the greatest potential harm is the damage to public confidence. Despite being considered an effective and safe by the WHO the AstraZeneca vaccine is now tainted by allegation that it is ineffectual or even dangerous. This is despite these claims being at odds with the data.

In reality, the vaccine prevents not only deaths and hospitalisations, but also hugely reduces asymptomatic transmission – something absolutely crucial in stemming the tide of the pandemic.

The suspension amplifies public perception that the vaccine is subpar. This has and will lead to “vaccine shopping”, where this highly efficacious vaccine is rejected in favour of others deemed more desirable.

The net result of this is rejection or delay of immunisation will be to inadvertently prolonging the pandemic. With confidence already badly affected, even quick reversal of the decision to suspend it may not be enough to shift public perception.

Alarming resurgence

Worse again, the decision to suspend programmes around Europe plays into the hands of anti-vaccine activists. Since the start of the pandemic, anti-vaccine propaganda has undergone an alarming resurgence. The advent of Covid-19 vaccines has seen a staggering rise in targeted disinformation and conspiracy theories propagated about the vaccine.

A decision by the Japanese government to suspend recommendations for the HPV vaccine for cervical cancer in 2013 saw uptake fall from 70% to 1% in under a year

Anti-vaccine falsehoods pivot on scaremongering, pushing baseless claims to worried audiences. These audiences don’t have to believe whole-heartedly for these poisonous fictions to have a negative effect. There is ample data demonstrating that negative messaging about vaccines is supremely effective at nudging people towards delaying or rejecting immunisation. The suspension of a vaccine is readily twisted in anti-vaccine propaganda and to an unaware observer, might give a veneer of credibility to dangerous fictions.

Vaccine hesitancy

Whether induced by anti-vaccine propaganda or otherwise, vaccine hesitancy is a spectrum and public fears have a marked effect. This is not hypothetical – a decision by the Japanese government to suspend recommendations for the HPV vaccine for cervical cancer in 2013 saw uptake fall from 70 per cent to 1 per cent in under a year, a disastrous failure in policy projected to lead to over 11,000 avoidable deaths.

Public fears over the safety of the MMR vaccine in the early 2000s saw the uptake plummet, leading to a dark renaissance of measles and other once nigh-on conquered infectious diseases. So bad is the situation that in 2019, the WHO deemed vaccine hesitancy a top 10 threat to public health.

The weaponisation of the suspension of AstraZenneca vaccine by anti-vaccine activists is sadly inevitable.

Of course, there should be no doubt decisions to suspend are made with the best of intentions and presumably after careful and considered statistical analysis of all available data, including some to which the public many not be privy. But in many parts of Europe, the decision to shut down programmes appears based on individual reports in insolation, contrary to WHO and EMA recommendations.

This seems supremely reactionary, and risks undermining public trust. The longer this situation endures, the worse the fallout. Hopeful this can be quickly resolved, as indeed it must. Widespread vaccination is imperative for a post-pandemic world - it is crucial we don’t lose sight of that.