On 17 March, the UK had reported 1950 cases and 81 deaths from coronavirus (COVID-19) infection. Already it was clear that most deaths were occurring in older individuals and those with underlying conditions. I had just seen a man with heart failure who was confused regarding the government guidelines for social distancing announced the previous day, and why he was “high-risk”. I was sure background risk of mortality was a major driver of pandemic deaths, and that electronic health records could help to answer my patient’s questions.

Using linked primary care data (CPRD: Clinical Practice Research Datalink), Laura Pasea and I started analyses in 3.8 million individuals in England to calculate baseline risk based on age, sex and underlying conditions. We used these calculations to estimate excess deaths in different pandemic scenarios over 1 year based on infection rate and impact of the pandemic.

The following morning, I had several calls with Harry Hemingway and Spiros Denaxas. Over the next three days we completed analyses, explored the concepts of “direct” (due to infection) and “indirect” (due to health system strain) effects of the pandemic, and convinced twelve colleagues from varying disciplines to join us. By 22 March, we had written a manuscript, which we published to preprint server, after sending to the Chief Medical Officer’s office. Our analyses, predicting between 30,000 and 70,000 excess deaths at a 10% infection rate received wide media coverage. The following evening, the UK entered lockdown. On 12 May, as lockdown started to ease in the UK, alongside a Lancet publication, we released a prototype online risk calculator for public, researchers, clinicians and policymakers, which can help decision-making whether about returning to work, staying at home or caring for relatives.

As of 23 June, there have been at least 42,927 COVID-19 excess deaths in the UK, 95% of which have occurred in people over the age of 70 years or with comorbidities. Sadly our estimates have proven to be in the right ballpark, and driving down infection rate remains the strongest defence against excess deaths, whether by direct or indirect effects of the pandemic. The importance of timely access to routine clinical and health service data has become even more important in the context of this public health emergency.