Staff shortages caused by the so-called 'pingdemic' have led to the cancellation of some Great Western Railway train services.
Local services between Bristol and Weston-super-Mare have been cut on weekdays and Saturdays from Monday 26 July until Friday 6 August.
The reduced timetable affects services to the popular seaside town during the first two weeks of the school holidays.
The train company says it has "taken steps to uphold" the level of service it provides to customers, resulting in a number of amendments to the timetable.
In a statement GWR said: “With rising numbers of staff unavailable to work because of testing positive for Covid or being contacted through track and trace, we have [this morning] taken steps to uphold the service level we are able to offer.
“This includes a limited number of planned cancellations, predominantly on some of our branch line services, as well as to other lower demand services for example at the very beginning or end of the day.
"We are writing to customers who have pre-booked tickets. Customers should continue to check their journey before leaving home for the very latest information.”
In response to the cancellations, new Metro Mayor for the South West Dan Norris has urged the public to continue to use face coverings when travelling despite legal restrictions being lifted - something he says is a :"wrong call" on the part of the Government.
He said: "These cancelled services are a warning sign that mask wearing needs to continue on public transport for the safety of passengers and staff.
"The Government has made the wrong call on this issue.
"Whilst we all want to go back to normality, if Covid cases continue to soar we won’t be going back to normal, we will be seeing more cancelled services and more staff having to self isolate.”
Great Western Railways has confirmed local Bristol to Taunton services will operate, and will make additional stops between Bristol and Weston.
High speed services between London and Weston/Taunton continue to operate as planned.