Covid by numbers: 10 key lessons separating fact from fiction | Coronavirus


1 The UK was hit by more than 1,000 separate outbreaks

Genomic sequencing has identified more than 1,000 different seeds of Sars-CoV-2 introduced in early 2020. Instead of one central outbreak, reverberating outwards like an explosion, we now know there were many erupting simultaneously across the country. There were far more imports of Sars-CoV-2 from France, Italy and Spain than from China – viruses can take indirect flights. The peak was early March, after the school half-term, but a popular holiday time for adults. At the Champions League football match at Anfield between Liverpool and Atlético Madrid on 10 March, 49,000 local supporters mixed with 3,000 fans of the opposing team, while schools in Madrid were shut and supporters could not attend matches. To add insult to injury, Liverpool lost 3–2, and 4–2 on aggregate.

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2 Reported Covid deaths depend on the day of the week

The daily counts on the news of the “28-day” death figures do not represent deaths that happened in the last 24 hours, but those newly reported. There is a clear weekly cycle, with the numbers tending to be higher on Tuesdays and Wednesdays because of reporting delays over the weekend. That has led to some dramatic differences: there were 560 deaths reported for England on Monday 18 January 2021, jumping to 1,507 the next day. Since these numbers are released at about 4pm each day, they become news and so are given journalistic prominence, regardless of relevance.

3 In the first year of Covid, over-90s had 35,000 times the risk of dying of Covid-19 as young children

There is an extraordinary difference in risks faced by different generations. Out of over 7 million schoolchildren aged between five and 14, 11 died with Covid-19 mentioned on their death certificate over the year (one in 660,000). In the same period, 469 died from other causes. At the other end of the scale, out of more than 500,000 people aged over 90, nearly 30,000 died with Covid-19 on their death certificate (around six in 100). That was 35,000 times the fatal risk experienced by schoolchildren.

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4 2020 saw the highest number of deaths since 1918 in England and Wales

There have been claims that the first year of Covid-19 was not particularly lethal compared to past years. But there were only two years when total deaths registered in England and Wales exceeded 600,000: 1918, the start of a global influenza pandemic, and 2020.

We should, of course, allow for changes in the size of the population. This shows steadily falling mortality rates and then a noticeable jump in 2020, back to a level not seen since 2003. The increase from the past five-year average was the largest since 1941, when Blitz casualties mounted. When we further consider the changing age profile, 2020 saw the biggest rise in age-standardised mortality rates for 70 years, since the major flu epidemic in 1951. Put in its proper context, 2020 was a historical outlier.

5 The UK has led the world in testing Covid treatments

The UK Randomised Evaluation of Covid-19 Therapy (Recovery) organisation has become the world’s largest collaboration for trials on people in hospital with Covid-19, with more than 180 hospitals and about 40,000 hospital patients taking part so far. Recovery takes advantage of the unique NHS infrastructure to simultaneously run several overlapping trials, so that each patient may be in many studies. The trials have been hugely influential. By March 2021, dexamethasone, a cheap steroid, was estimated to have saved 22,000 lives in the UK and more than 1 million worldwide. Almost as valuable as finding effective treatments, Recovery trials also established things that did not show clear benefits, such as hydroxychloroquine and convalescent plasma, both touted by the then-US president.

6 People who have died with Covid have on average lost about 10 years of life

Some vulnerable people who died in the first wave would otherwise only have survived a short period longer. This “mortality displacement” often shows when a cluster of deaths due to extreme heat or cold is followed by a dip in mortality rates. At the start of the first wave, one of us (DS) was quoted as saying, “many people who die of Covid would have died anyway within a short period”, while others estimated that this proportion could be more than half. We were proved wrong by the limited deficit in deaths over the following year. It’s been estimated, on average, that about 10 years of life are lost from Covid-19 deaths in the UK, and 16 years globally.

7 Most people died “of” Covid rather than “with” it, but most have also had other medical conditions

There have been many claims Covid-19 has been incidental to many people’s deaths. When Covid-19 was mentioned on the death certificate in the first wave, it was the underlying cause of mortality for more than nine in 10 registrations. That changes somewhat when the virus becomes rarer, with the proportion dying “with” Covid-19 at 32% in late April 2021. When there is less virus around, cases tend to be less severe, though the present infection was considered to have contributed to the death in some way.

It is rare for there to be only one primary cause of death. In the first wave there were pre-existing conditions in 91% of deaths involving Covid-19, with dementia and Alzheimer’s disease present in 25%.

8 Alcohol consumption stayed the same during lockdown

Personal responses to lockdowns, like the virus, vary hugely: the Alcohol Consumption in England project found the proportion of people reporting high-risk drinking rose substantially during the first wave, but the proportion reporting cutting down on their consumption also went up. Although patterns of drinking change, looking at paid duty, the provisional total amount of alcohol consumed appeared to remain stable. The Alcovision survey of more than 80,000 drinkers showed that even when pubs were closed in lockdown, the average number of drinking days did not change.

9 Most people with Sars-CoV-2 don’t infect anyone

It’s been estimated, when introduced into susceptible communities not taking precautions, that about 75% of people who caught the original strain of the virus did not go on to infect anyone else. A small minority (10%) were estimated to lead to the great majority (80%) of new cases. Some may be particularly infectious, while “super-spreader” events can also occur. There was a choir practice in Washington state where, after over two hours of singing closely together, one person with “cold-like” symptoms led to 52 infections among 60 other singers, two of whom later died. Prolonged proximity increases the chance of passing it on, although the absolute risk can seem low: individuals infected with the original strain were estimated to infect only about one in six members of the same household.

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10 The pandemic has been a net lifesaver for young people

Compared with the past five-year average in England and Wales, there were more than 300 fewer deaths registered in 2020 for people aged between 15 and 29. One putative explanation is reduced accidents and violence: meaning 300 fewer grieving families. These families do not know who they are, in contrast to the 115 families of those in this age group who died with Covid-19. But living through the pandemic has had a large impact on the mental health of younger adults.

From Covid by Numbers, by David Spiegelhalter and Anthony Masters