Department for Health and Social Care data shows 12,308 people were told to self-isolate after being in contact with someone who tested positive for Covid-19 in the week to July 7 – the latest available data.
Contact tracers ask new patients to give details for anyone they were in close contact with in the 48 hours before their symptoms started.
The figures show 13,411 people who came into close contact with someone who tested positive for Covid-19 across the Black Country and Staffordshire were transferred to Test and Trace in the week to July 7.
It means 1,103 contacts were not reached by the service. The figures do not include those told to isolate in specific settings such as schools and prisons.
Across England, more than 160,000 cases were transferred to the contact tracing system between July 1 and 7, with 381,000 people identified as coming into close contact with someone who had tested positive – also the highest number since the week ending January 20.
Separate figures also show that more than half a million alerts were sent to users of the NHS Covid-19 app in England and Wales telling them to self-isolate.
Isolation is recommended but not mandatory, if someone is alerted by the app, while those contacted by Test and Trace have a legal duty to self-isolate.
Unite said hundreds of employees are off work at some sites, especially in the automotive sector, with alerts from the NHS app causing “havoc” on production lines.
There are calls to bring forward the August 16 date, where the fully vaccinated will not have to self-isolate if they come into contact with someone with Covid-19.
The Government is urging those told to self-isolate to follow the guidance.
It comes as the number of coronavirus patients in hospitals across the region rose by more than 50 per cent in a week, figures show.
Trusts across the Black Country and Staffordshire were caring for 136 Covid patients as of July 13.
NHS England data shows the number of people being treated in hospital for Covid-19 by 8am on July 13 was up from 87 on the same day the previous week