In recent decades, the share of the population aged 65 years and over has nearly doubled on average across OECD countries, increasing from less than 9% in 1960 to more than 17% in 2019. Declining fertility rates and longer life expectancy (see indicator “Life expectancy by sex and education level” in Chapter 3) have meant that older people make up an increasing proportion of the population in OECD countries. Across the 38 OECD member countries, more than 232 million people were aged 65 and over in 2019, including more than 62 million who were at least 80 years old. As ageing represents one of the key risk factors for serious illness or death from COVID‑19, the pandemic has driven home the need to ensure that health systems are prepared to adapt to the changing needs of an older population.