How Excel may have caused loss of 16,000 Covid tests in England
Explains what happened in simple language, but oh gawd .... manual data input
Were labs sending all the test data every time via Excel, instead of just the new data 
https://www.theguardian.com/politics/2020/oct/05/how-excel-may-have-caused-loss-of-16000-covid-tests-in-england
... the rapid development of the testing programme has meant that much of the work is still done manually,
with individual labs sending PHE spreadsheets containing their results.
Although the system has improved from the early days of the pandemic, when some of the work was performed with phone calls, pens and paper, it is still far from automated.
In this case, the Guardian understands, one lab had sent its daily test report to PHE in the form of a CSV file – the simplest possible database format, just a list of values separated by commas.
That report was then loaded into Microsoft Excel, and the new tests at the bottom were added to the main database.
But while CSV files can be any size, Microsoft Excel files can only be 1,048,576 rows long – or, in older versions which PHE may have still been using, a mere 65,536.
When a CSV file longer than that is opened, the bottom rows get cut off and are no longer displayed.
That means that, once the lab had performed more than a million tests, it was only a matter of time before its reports failed to be read by PHE.