Emergency timetables have been introduced by Arriva for its bus services across the region and will come into force from Monday.
Key routes will continue to operate and will be "tailored" as official government advice is updated.
West Midlands Railway is resuming with its standard service, but said trains may be subject to last-minute cancellations due to on-board staff shortages.
A spokesperson for Arriva Bus said: "In light of the government's latest advice and recommendations, as well as planned school closures, we can confirm as of Monday, March 23, we have had to reduce the frequency of some services.
"However, we will still be operating our key routes to ensure customers can continue to access critical services, and we are continuing to tailor our service changes in line with ongoing advice from the government and public health bodies.
"Customers will be made aware of any ongoing service changes via our website and social media channels.
"We understand that there are many concerns and uncertainty about the current situation.
"The health and wellbeing of our customers and employees is our primary concern.
"Our dedicated team are monitoring the situation closely and we will bring you the latest updates in line with Government advices as they arise."
The full emergency timetables will be online at arrivabus.co.uk/coronavirus over the next 48 hours.
West Midlands Railway is resuming its services as normal, but said trains may be cancelled due to staff shortages.
Jonny Wiseman, customer experience director for the company, said: “We are currently operating our normal timetable but due to the impact of COVID-19 on train crew availability, some services may be subject to short-notice cancellation and passengers are advised to check live departure boards.
“While the government has advised against unnecessary travel, we know that thousands of people, particularly those delivering essential public services, need to keep moving. That’s why we are fully committed to ensuring we continue to run a resilient, reliable railway in these challenging circumstances.”
This comes as other public transport operators across the country have taken similar measures.
Northern Trains said there will be cancellations on a dozen routes on Thursday “as a result of Covid-19”.
The affected routes include Liverpool-Manchester Airport, Leeds/Sheffield–Nottingham and Newcastle-Carlisle.
South Western Railway said it is cancelling trains at short notice as, “like most organisations, we’re seeing more staff having to stay at home unwell”.
Govia Thameslink Railway has cancelled a “small number of services” due to workers being unwell or self-isolating.
Great Western Railway has announced its sleeper service between London Paddington and Penzance – known as the Night Riviera – will be suspended after Friday “to protect our customers and colleagues”.