Concerns over the potentially harmful side-effects of Covid-19 vaccines have reverberated around the world this year, leading to restrictions and pauses in a number of programmes.
In March, more than 20 countries worldwide either partially or fully suspended the AstraZeneca (AZ) vaccine, following reported links to blood clots. (Most have since reinstated use of the vaccine with an age restriction.) The US also temporarily suspended the Johnson & Johnson (J&J) vaccine last month after similar concerns.
But have these incidents made people more reluctant to get vaccinated? And when people say they are “hesitant”, what does that mean in practice?
[see also: International coronavirus vaccine tracker: how many people have been vaccinated?]
According to the polling company YouGov’s international survey on vaccine willingness, the figures are mixed across Europe. In France, where vaccine scepticism was high even before Covid-19, the inclination to get vaccinated has actually risen since use of AstraZeneca’s vaccine was temporarily paused on 15 March. Before then, the latest survey had half of respondents saying they were willing to get vaccinated. This fell to 49 per cent by 17 March, but by 24 March, five days after the vaccine was reinstated for over-55s, it had risen again to 54 per cent. The latest poll (27 April) puts the French figure at a high of 60 per cent.
In Germany, despite an initial rise in vaccine willingness post the AZ suspension (from 64 per cent on 11 March, to 68 per cent on 25 March), it dipped slightly after 1 April, when the vaccine commission recommended those under 60 receive a different second dose even if they had had AstraZeneca as the first. Since then willingness has risen again to a new high of 71 per cent on 5 May. Italy similarly saw willingness to be vaccinated drop slightly to 71 per cent (from a high of 75 per cent at the end of March), but then recover.
On the whole, confidence has risen across most of Europe as friends and family members receive jabs without suffering any side-effects.
In the UK, YouGov found that the AZ pause in Europe had minimal effect on perceptions of safety. A separate survey from the University of Stirling found that the government’s decision to recommend other vaccines to those aged under 30 had no effect on the general public’s intention to get vaccinated.
Meanwhile, in the US, a 19 April poll by the Census Bureau found that just 11.5 per cent of adults probably wouldn’t get vaccinated, down from 15.6 per cent on 29 March. YouGov also found that vaccine willingness increased from 55 to 65 per cent of people between 12 April and 19 April, and a CNN poll found 26 per cent of people were vaccine-hesitant (21-26 April) – down from 28 per cent in March. Although these polls ended during or shortly after the J&J pause (from 13 to 23 April), none showed an increase in hesitancy.
Is vaccine uptake being impacted by hesitancy?
The impact of hesitancy on actual uptake of vaccines is hard to measure. Other factors – such as the number of doses available, or the age groups that are now allowed to receive them – also affect how many people are being vaccinated at any one time.
In the US, figures from the Centers for Disease Control and Prevention show that the temporary pause of the J&J single-shot vaccine led to a fall in people getting the jab. Since the pause, both Moderna and Pfizer have also seen growth in new daily doses decline.
Hesitancy doesn’t necessarily arise from paused vaccines: the easiest-to-reach parts of the US may simply have already received had their vaccinations, leaving only the harder-to-persuade communities (who tend to be more Republican). But, either way, the declining growth figures pose a problem for the US roll-out.
Figures from European countries (where data is available) show the number of people receiving AstraZeneca was also negatively affected by the suspensions and introduction of age limits. However, since reintroduction, figures for the jab have risen in Iceland, Italy and Germany, and there are no clear signs that hesitancy is more to blame than delivery shortfalls, or a smaller pool of eligible people due to age limits.
Furthermore, unlike in the US, if hesitancy is slowing down the AstraZeneca uptake in some European countries, it isn’t affecting other jabs. Pfizer and Moderna appear to have made up for the AstraZeneca shortfall in most countries where data is available.
Young people are key
The next big test for the leading vaccination programmes (which so far are predominantly in wealthier nations), will be whether high uptake continues as vaccine eligibility widens down the age pyramid.
Younger people have consistently polled less enthusiastically towards vaccination – which may be a consequence of being less susceptible to the disease, or because they are most likely to be at risk of extremely rare clotting side-effects. (For this reason, some countries have recommended the AstraZeneca jab should be used only in older age groups.)
Another factor countries will be watching is whether the number of people getting a second jab drops below the first-jab figures. So far, it seems most people are returning: in England, second jab figures for the over-80s stand at 98 per cent of the first-jab figures of 12 weeks ago. In Israel, roughly 97 per cent of the over-70s who have received one jab have already had their second.
Outside of the US, there aren’t signs yet that uptake has been seriously affected by side-effect controversies or harder-to-reach demographics.
The hope therefore is that the real-life vaccine uptake continues to outperform any vaccine-hesitant polling, especially among the young.
[see also: Why is the highly vaccinated Seychelles experiencing a Covid spike?]