2021

Review of the year

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HE phenomenal covid-19 vaccine roll-out

in 2021 demonstrates some of the best

and worst aspects of modern medicine. It

is now estimated that about 8 billion doses

have been put into people’s arms in the past

12 months – an incredible effort by health

services around the world. But the vaccines

haven’t been distributed equally. While many

people in high-income countries will have

received three jabs by Christmas, only about

5 per cent of people in low-income countries

were expected to have had at least one by

the end of the year.

While the first few vaccines given outside

a clinical trial happened in December 2020, it

was in January 2021 that immunisation started

taking off in the UK and other wealthy nations,

with limited initial supplies meaning shots

had to be prioritised for the most vulnerable.

Figures on the real-world effectiveness of

the vaccines are encouraging. In the UK, two

shots of the Oxford/AstraZeneca or Pfizer/

BioNTech versions reduced infections by the

delta variant by 67 and 80 per cent respectively,

hospitalisations by 92 and 96 per cent, and

deaths by 91 and 90 per cent. If vaccinated

people do get infected, they are 63 per cent

less likely to pass the virus on to others. We

don’t know yet how different these figures

might be for the omicron variant.

There have been serious, but rare, side

effects. In March, it became clear that the

Oxford/AstraZeneca vaccine can cause a blood-

clotting syndrome called vaccine-induced

immune thrombotic thrombocytopenia,

or VITT, which it turned out is also associated

with the Johnson & Johnson vaccine,

and is more likely in younger people.

In June, it emerged that the Moderna

and Pfizer/BioNTech vaccines occasionally

trigger a form of heart inflammation called

myocarditis. This is more often seen in

younger people, particularly males, although

the incidence of myocarditis after covid-19

itself is six times greater.

The last few months of 2021 saw wealthy

nations offering vaccine doses to under-16s,

and in some countries, such as the US, to

children as young as 5 years. Alongside this, a

push for third or booster shots for vulnerable

or older people and frontline healthcare

workers has formed the cornerstone of Israel’s

efforts to tackle the delta variant and the UK’s

plans to get through a difficult winter and

prepare for omicron.

Vaccines have also enabled countries that

initially took tougher approaches to managing

the pandemic to begin to reopen after lengthy

lockdowns. New South Wales in Australia,

for instance, kept its promise of easing

restrictions, including in Sydney, once 70 per

cent of people over 16 were fully vaccinated.

But the plan for wealthy countries to help

low-income ones through a vaccine delivery

coalition called COVAX has made slow

progress, hindered partly by high-income

nations buying so much stock for themselves

and by an export ban in India that stopped

expected supplies from a large manufacturer

there. “We hit many problems,” says Seth

Berkley of the health body Gavi, one of the

organisations leading COVAX.

Meanwhile, in high-income countries where

supply is plentiful, a minority of people are still

resisting vaccination, mainly due to mistaken

beliefs about side effects. This helps drive

circulation of the virus in the community,

risking the lives of people who are vaccinated

but still vulnerable due to age or ill health. ❚

Billions of covid-19 shots

given in wealthy nations

A vaccination centre

in a school in the

Philippines in August

By the end of 2021, several countries were on a third

round of coronavirus vaccinations, reports Clare Wilson

Coronavirus

22 | New Scientist | 18/25 December 2021