Delta variant cases have spiked in the UK, but deaths have not - a sign vaccines are working

• The Delta variant is driving a surge of COVID-19 cases in UK, like in many other places.
• But deaths in the UK have not spiked nearly as much as they did during prior surges.
• The UK has fully vaccinated 72% of its population, and that's kept deaths down even as cases rose.

The highly contagious Delta variant is spurring surges of COVID-19 across the globe.

But in the UK, where 71.8% of the population is fully vaccinated, the new surge is not bringing the same death toll as past coronavirus waves.

The UK government's coronavirus dashboard features daily counts of positive COVID-19 tests and deaths. A comparison of those two data sets shows how the relationship between infections and deaths has changed over time.

Throughout July, the ratio of deaths to cases in the UK has remained much lower than it was at any prior point of the pandemic.

In the early days of the UK's first wave last spring, the ratio of deaths to cases shot up. Similarly, in the wave seen last winter, that ratio rose notably again.

The UK's latest surge began in June. By July 1, the seven-day average of new cases had grown to nearly six times what it was on June 1. The new wave is producing almost as many daily cases as the surge the UK saw in January. But deaths have not risen nearly as much.

The low ratio is probably because of vaccines, which have proven highly effective at preventing severe disease, hospitalizations, and deaths.

A UK study found that two doses of the Pfizer or AstraZeneca vaccines were 88% and 67% effective, respectively, at preventing symptomatic COVID-19 from the Delta variant - the UK's dominant strain.

Moderna and Johnson & Johnson have both said that lab tests suggest their vaccines are also highly effective against Delta, though peer-reviewed research on those shots' real-world effectiveness in the face of Delta has not yet been published.

Overall, the effectiveness of widespread vaccination is evident in the UK's shrinking ratio of deaths to cases over time. In early February, just 1% of the UK population was fully vaccinated, and about 25% of the population had received one dose. During that time, the UK counted an average of five deaths for every 100 new cases.

Now that the UK is 71.8% vaccinated against COVID-19 - and 88.4% of people have received at least one dose - the death-to-cases ratio is nearly zero.