https://thenextweb.com/syndication/2020/10/10/why-the-uk-was-dumb-to-use-microsoft-excel-to-count-coronavirus-cases/

Public Health England has admitted that 16,000 confirmed coronavirus cases in the UK were missed from daily figures being reported between September 25 and October 2. The missing figures were subsequently added to the daily totals, but given the importance of these numbers for monitoring the outbreak and making key decisions, the results of the error are far-reaching.

Not only does it lead to underestimating the scale of coronavirus in the UK, but perhaps more important is the subsequent delay in entering the details of positive cases into the NHS Test and Trace system which is used by a team of contact tracers. Although all those who tested positive had been informed of their results, other people in close contact with them and potentially at risk of exposure were not immediately followed up (ideally within 48 hours). This was a serious error. What could have caused it?