The Economist - USA (2021-02-13)

18 The Economist February 13th 2021
BriefingMaking vaccination work

O

n february 1stresearchers around the

world saw the tweet for which they had

been waiting: “We say with caution, the

magic has started”. Eran Segal, a scientist at

the Weizmann Institute, had been posting

regular updates on the course of Israel’s co-

vid-19 epidemic since its mass vaccination

campaign had begun six weeks earlier. By

February 1st he was seeing the number of

hospitalisations dropping significantly

among the over-60s—a cohort in which the

number vaccinated had reached 70%, seen

as a crucial level, three weeks before. After

an expected but still somewhat nail-biting

lag, the vaccine was doing its thing.

By February 6th about 85% of the

over-60s in Israel—and 40% of the general

population—had received at least one dose

of the Pfizer/BioNTech mrnavaccine (or in

a few cases the Moderna mrnavaccine)

and 75% of the over-60s had received their

second dose, too. In that age group hospital

admissions for covid-19 were about two-

thirds what they had been at their peak in

January and still falling (see chart 1 on next

page). At the same time, the country as a

whole was seeing its caseload rise.

The vaccine was not the only thing

which arrived in Israel late last year. So did

b.1.1.7, a highly contagious variant of sars-

cov-2, the virus responsible for covid-19,

which was first identified in Britain in Sep-

tember. It set about filling up hospital

wards in Israel just as it has done in Britain,

Ireland and Portugal. Despite an extended

lockdown it is still doing so.

It is no surprise that sars-cov-2 has

evolved new biological tricks over a year

spent infecting more than 100m people.

But the near simultaneous arrival of not

just b.1.1.7 but also b.1.351, which is now the

dominant strain in South Africa, and p.1, a

variant first seen in Brazil, is making the

roll-out of mass vaccination more compli-

cated and more confusing than might have

been hoped when the first evidence of safe,

effective vaccines became available last

November. How fast the various new vari-

ants can spread, how well today’s vaccines

work against them and how soon new vac-

cines better attuned to them—and to the

other variants which will turn up over

time—become available will determine the

course of the pandemic.

Testing the bounds

As of February 10th at least nine vaccines

had been authorised for use in one or more

countries. The Pfizer/BioNTech vaccine,

first out of the gate, has now been author-

ised for use in 61, as well as for emergency

use by the who. The number of doses ad-

ministered, 148m, now exceeds the num-

ber of confirmed covid-19 cases recorded

over the entire course of the pandemic. All

of the vaccines appear very good at pre-

venting severe cases of covid-19 of the sort

that lead to hospitalisation and/or death;

in trials which compared the vaccinated

with control groups the efficacy with

which the various vaccines prevented

these outcomes was 85-100%.

Their efficacy against all symptomatic

cases of the disease found in trials has

been lower, ranging between 66% and 95%.

Some of that range is down to intrinsic dif-

ferences between the vaccines. Some is

down to trials being done according to dif-

ferent protocols and in different popula-

tions, sometimes against different varia-

nts of the virus. It is hard to disentangle

such effects. The general message, though,

is fairly clear. The vaccines make serious

cases of all sorts very rare, and mild-to-

moderate cases caused by the original

strain of the virus a lot rarer than they

would be otherwise.

That is undoubtedly good news; it less-

ens the death toll, the suffering and the

strain on hospitals. But the situation is not

perfect. For one thing mild and moderate

cases can be worse than they sound. Many

The race between vaccines and variants is heating up

Obstacle course

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20 Vaccine hesitancy