Covid-19: How close is the light at the end of the tunnel?

11th February, 2021

Will it ever end? In November, we were celebrating the announcement that the BioNTech/Pfizer vaccine seemed to be highly effective against Covid-19, followed with bewildering speed by similar claims for the Sputnik V, Moderna and Oxford/AstraZeneca vaccines. Nearly three months later, hospitals are overwhelmed and the global death toll is climbing twice as fast as in the worst days of the first wave. At a time like this, I reach for my calculator.

Without minimising the suffering so many people are enduring, I think there is potential for rapid progress very soon. (I am writing these words at the end of January 2021.) There are two reasons why these vaccines, some highly effective, have not yet done anything obvious to save lives or protect hospitals. The first is evident: not enough people have been vaccinated so far. Israel and the United Arab Emirates are well into a remarkable mass vaccination campaign, but most major economies have given a first dose to 2 or 3 per cent of their population.

The second reason is that the vaccine takes time to work. In the UK, Margaret Keenan received a first dose of vaccine bright and early on December 8, but it needs a couple of weeks to provide much protection. She and her fellow first-day vaccinees were much safer by Christmas. Infection takes on average five days to develop into symptoms, so there would have been little sign of any benefit before New Year’s Eve. It usually takes another 10 days before there is much risk of admission to an intensive care unit, and still more before there is a risk of death. Only now are those first few vaccines, weeks ago, beginning to reduce the death toll. It is like turning around the proverbial oil tanker.

The UK had vaccinated (with first dose) about 1 per cent of its population by Christmas, but funeral directors will not notice the effect of that until Valentine’s Day. It seems wretchedly slow. So let me now share the good news: a small number of well-targeted vaccinations can have a huge effect.

Covid-19 is, overwhelmingly, a disease that spares the under-sixties. According to Yifei Gong and Stuart McDonald of the Covid-19 Actuaries Response Group (ARG), 36 per cent of all Covid-19 deaths in the UK were of people who were resident in a care home — a group of 400,000 people. Another 30 per cent of deaths were among people aged 80 or more, a group of three million. (These calculations cover the first wave of the pandemic, running up to November 20.)

The same broad pattern applies in any rich country with an elderly demographic. Vaccinate the top priority groups — just a few per cent of the population — and you might reasonably hope to prevent two-thirds of the deaths. The UK government announced on Monday that nearly 80 per cent of those aged 80 and over had received a first dose of vaccine; hardly a surprise, with more than six million doses already administered. Those people, highly vulnerable until now, will be well protected by Valentine’s Day, with deaths prevented in March. The US and EU are behind, but not standing still.

We should expect painfully little to happen, until it starts to happen fast. The ARG estimates that the vaccination that has already taken place is making deaths in hospital about 5 to 10 per cent lower than they would otherwise be. That is important, but imperceptible in the roar of the second wave. In contrast, by the end of February, vaccination should reduce deaths by two-thirds; by the end of March, they should be reduced by about 85 per cent, relative to a no-vaccine scenario.

This projection assumes very high protection and very high take-up, as well as continued acceleration of the vaccination programme. There is room for things to fall well short. But it is quite reasonable to expect dramatic progress in February.

The people who are being admitted to hospital and to intensive care units are, on average, a lot younger than the people who are dying. For this reason the vaccine will not protect hospitals as quickly as it will prevent deaths. But the story arc is the same: nothing happens for a while, and then a lot happens. By early March, hospital admissions should be down 60 per cent and ICU admissions down a third, compared to where they would be without a vaccine, according to the ARG’s calculations.

Why, then, are we still talking about lockdown? Because the virus can spread very rapidly indeed. We have learnt that lesson the hard way, twice. Let’s not forget. A one-third reduction in ICU admissions could be swamped by a day or two of uncontrolled growth, and certainly by a week of carelessness. We will be out of the worst far more quickly, with fewer deaths, if we meet the vaccine halfway by suppressing the virus with social distancing. That need not mean a draconian lockdown, but it will mean that normality is postponed.

There is another reason for hope: the vaccine may also prevent transmission of the virus. If it does, then every dose brings us closer to herd immunity. Vaccinating 10 per cent of the population won’t do much for herd immunity, but vaccinating half of us will go a long way towards protecting the other half.

Hemingway’s The Sun Also Rises has a character who ruefully notes that he went bankrupt gradually — and then suddenly. In countries fortunate enough to have plenty of vaccine doses, that is how this pandemic will end, too.

Written for and first published in the Financial Times on 29 January 2021.

My new book, “The Data Detective” was published in the US/Canada on 2nd February.

“Nobody makes the statistics of everyday life more fascinating and enjoyable than Tim Harford.”- Bill Bryson

“This entertaining, engrossing book about the power of numbers, logic and genuine curiosity”- Maria Konnikova

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