The number of deaths in England and Wales last year hit a 12-year high, triggering a drop in life expectancy for men and women.
There was a surge in deaths between 2014 and 2015, with flu thought to be to blame for taking the lives of a significant number of people aged 75 and over.
As a result, life expectancy at birth fell by 0.2 years for men and 0.3 years for women between 2014 and 2015.
Life expectancy fell to 79.3 years for men and 82.9 years for women, analysis by the Office for National Statistics (ONS) shows.
In England alone, life expectancy at birth fell by 0.2 years for both sexes. For men, this was the first fall since 1993.
Female life expectancy at birth last fell in 2012.
Life expectancy for men aged 65, 75, 85 and 95 also fell by 0.2 years in 2014/15. This was the first year-on-year fall for male life expectancy at age 65 and 75 since 1995
The new data from the ONS shows that in England and Wales, there was a rise of 28,189 deaths in 2015 (up 5.6%), from 501,424 deaths in 2014 to 529,613 deaths in 2015.
This is the highest number since 2003, when there were 539,151 deaths. The percentage increase in 2015 is the largest year-on-year rise since 1967 to 1968 (6.3%).
The ONS has previously published estimates of deaths for the winter period alone and suggested the substantial rise seen there may be partly due to the lack of effectiveness of the year's winter flu vaccine.
The vast majority of the extra deaths in 2015 were registered in the first three months of the year, coinciding with a peak in flu, the new analysis shows.
There were 24,065 more deaths in the first three months of 2015 compared with the same period in 2014, with 11,865 of these extra deaths registered in January alone, when flu was circulating at its highest levels.