Spreadsheets are only as good as their underlying formulae and the checks that control them.
In October 2020 almost 16,000 positive Covid-19 cases disappeared between testing labs and England’s contact-tracing system. An outdated Excel file format had been used which simply did not have enough rows.
The effects of this Excel lapse have been fatal. One estimate, by the economists Thiemo Fetzer and Thomas Graeber, is that it led to 125,000 further cases and 1,500 deaths.
So always take care with spreadsheets and check the results generated by them.