You report local efforts to supplement the national Covid contact-tracing operation (“Efforts ramped up”, Jan 11) which is good news as far as it goes.

However, it looks rather like the closing of a big stable door after a whole herd of horses has galloped half way down the road.

The centralised scheme operates on the basis that a test result is returned in 24 hours (still frequently not achieved), and contact-tracing reaches a minimum of 80% of contacts within a further 48 hours (i.e. 72 hours from from the original positive test). This has never been achieved with consistency, and the general success-rate of the central system is around a fluctuating 60%. Local teams, where they have been used, report success rates generally over 90%.

You report that the local supplement is picking up failed contacts after 48 hours, and aiming to reach them in a further 72 hours (i.e. at least 6 days after the original positive test). While it is no doubt better than merely giving up, any infected contacts are by this time themselves likely to be already potentially infectious.

The government originally bypassed the existing locally based teams and laboratories that could have received additional resources, and instead designed a central scheme, against expert advice, that could not be operational when it was originally needed, hence in part the Spring disasters, and would always struggle to produce minimally acceptable results.

The central “NHS” privatised Test & Trace, run by companies with little or no experience in health provision, and with a long chain of sub-contractors making accountability difficult, has so far cost, according to the National Audit Office, around £22bn. SAGE has judged its effect on the spread of the virus as “marginal”. Most of these companies have long experience of making big profits out of government contracts, and know how to cut contractual corners and how to cost penalties for breaches into the price they charge.

We should be able to expect better. Meanwhile, we all need to do better, not least by assuming for the moment that anyone we meet is potentially infected, and that we ourselves are also potentially infected. That way, the failures of test and trace will be less damaging.