With the Christmas getaway beginning, Omicron is taking its toll on the UK's rail links.
A number of train operators have had to cancel services due to coronavirus-related shortages and some firms are running reduced timetables due to workers being off sick or isolating.
As people are told to work from home, demand for rail travel has also plummeted.
Passenger numbers were at 53 per cent of pre-pandemic levels on December 20, according to preliminary statistics from the Department for Transport. That is down from 61 per cent a week earlier, and 68 per cent on Monday December 6.
And CrossCountry passengers will face major disruption on Christmas Eve and New Year's Eve due to strike action.
A spokeswoman for the Rail Delivery Group, which represents train operators, said: “Like everyone else, our staff are susceptible to the virus but as we showed last year during the pandemic, we will ensure that key workers can get to where they need to be.
“We aren’t able to run every train as planned at the moment but we know people want confidence that their train is going to turn up so we will be working hard to give clear, accurate and timely information and people should check before they travel.”
In light of the disruption, ITV News has taken a look at which operators are struggling under the weight of Covid disruption - and what options passengers have if their journey is affected.
Avanti West Coast
Avanti West Coast says: “The pandemic is unfortunately resulting in some staff shortages.
“We’re doing everything we can to run our full timetable but there may be some short-notice cancellations.”
A number of trains were cancelled on December 23, with some other services running altered routes due to staff being unavailable.
The firm has removed all peak ticket restrictions over the Christmas period in an effort to spread demand across it services.
Check your Avanti West Coast journey here.
In the past week, Chiltern Railways has had to cancel trains on December 16, 17 and 20 due to staff shortages.
The operator did not specify whether these shortages were Covid-related.
Chiltern said it expects its trains to be "busier than usual" on Christmas Eve due to CrossCountry strike action. Passengers have been advised to allow extra time and check their journey before travelling.
Check your Chiltern Railways journey here.
CrossCountry said it is “expecting widespread disruption to services this week”.
It went on: “Please pull your journey forward to sooner rather than later to get to your end destination as early as possible.”
Dozens of trains are being cancelled by the company each day, and many others have fewer carriages than usual.
On Christmas Eve and New Year's Eve the operator will be running a "severely amended service" due to strike action.
CrossCountry tweeted: "Due to planned strike action by members of the RMT union, we will only be able to run a very limited timetable on this Friday, with the cancellation of many of our services. Avoid travelling on this day."
You may use your ticket for December 24 on December 23 if you are able to travel earlier. If you decide not to travel you are entitled to a full refund for unused tickets dated 24 December due to the disruption. This can be claimed via your ticket retailer.
On Christmas Eve CrossCountry will run a reduced service between:
Edinburgh and Plymouth
Manchester Piccadilly and Bournemouth
Birmingham New Street and Leicester
On Christmas Eve CrossCountry will not run any services between:
Aberdeen and Edinburgh
Glasgow Central and Edinburgh
Derby and Nottingham
Leicester and Stansted Airport (a bus replacement runs between Leicester and Peterborough)
Cheltenham Spa and Cardiff Central
Newton Abbot and Paignton
Plymouth and Penzance
Check your CrossCountry journey here.
Govia Thameslink Railway - Southern, Great Northern and Thameslink
Govia Thameslink Railway said a train crew shortage means there will be a reduced service across the Southern, Thameslink and Great Northern network until the end of the day on Christmas Eve.
Greater Anglia said it has removed trains from its timetables due to falling passenger numbers “as people follow advice to work from home”.
It added: “We also have to plan for our staff being affected by the Omicron variant, especially as we’re already starting to see the early signs of its impact, to ensure we can continue to provide a reliable service.”
The operator introduced an amended timetable on December 20.
Passengers who have booked a ticket on a cancelled service can travel on either the train before or after.
Check your Greater Anglia journey here.
Great Western Railway
Great Western Railway has cancelled some services and staff training as it is impacted by staff shortages.
The firm said the present effect on services is limited when considering the number of trains operating - but that situation is fluid.
A spokesperson for GWR said: "With rising numbers of staff unavailable to work because of testing positive for Covid and having to self-isolate we have taken steps to maintain service levels across the network, including cancelling all non-safety critical staff training.
"Unfortunately, this also includes planned cancellations designed to minimise the impact on as many customers as possible. These are predominantly affecting our branch line services in Devon and Cornwall.
"Please check your journey before you leave home. If a train is cancelled, customers will be able to travel on a service before or after their booked train."
Check your GWR journey here.
London and North East Railway
The network said: "Due to increased driver and train manager absence from coronavirus, we are implementing an amended timetable from December 20.
"Through implementing planning cancellations, we aim to protest the rest of the timetable. We may still have a number of unplanned cancellations due to staff resource on the day."
LNER said its trains are "very busy this week" and encouraged people to reserve a seat.
Check your LNER journey here.
Northern said it is operating amended timetables due to “Covid and crew unavailability and major engineering works”. Disruption is expected to continue until at least January 3.
Online journey planners including websites and apps are being updated with any planned cancellations however there will be some short notice cancellations on the day.
The network "strongly advises" anyone travelling to check before they travel.
Northern's website says: "If your train has been cancelled, you can travel on the earlier or later Northern service. Trains on these routes are expected to be busier so please allow additional time to travel.
"We are adding standby buses, where available, to locations across the network to support if required."
Check your Northern Rail journey here.
ScotRail is running an amended service on several routes until further notice due to Covid-19 related illness.
On December 22, the operator tweeted: "Please check your journey before travelling. A growing number of our team are having to self-isolate, limiting the number of trains we are able to run."
Check your ScotRail journey here.
Southeastern has cancelled a number of services due to shortages of train crews on December 17, 18 and 20.
Ticket acceptance was in place at no extra cost on a number of bus routes.
There will be no trains between Lewisham and Sidcup/Hayes from December 27 to January 3 due to engineering works.
Check your Southeastern journey here.
South Western Railway
Engineering work is being carried out on South Western Railway lines over the festive period.
SWR tweeted on December 22: "Over the coming weeks we’re sorry that planned engineering works and the impact of Omicron may affect your journey."
The firm has put its festive timetable online - you can get more information and check your South Western Railway journey here.
The network said delays and short-notice cancellations over the next fortnight are due to staff sickness and “a lack of available staff caused by industrial relations issues”.
If a service you had planned to travel on does not operate, your ticket will be valid on the next available TransPennine Express service.
Ticket acceptance arrangements are in place - find out more and check your TransPennine Express journey here.
Transport for Wales
Transport for Wales has moved to an emergency timetable following the emergence of Omicron.
Traveline Cymru tweeted on December 22: "Transport for Wales have introduced a temporary reduced timetable to prepare for expected staff shortages due to the Omicron variant.
"It’s designed to reduce late-notice cancellations and provide more reliability over the festive period.''
Passengers have been urged to book ahead so operators can plan for increased demand.
Check your Transport for Wales journey here.
Refunds and compensation
If the train journey you are making, or have booked to make, is delayed or cancelled you may be entitled to a full refund from the retailer of your ticket, or compensation from the train company that caused the delay.
Refunds: You may be eligible for a refund if your train is delayed or cancelled and you choose not to travel. Your unused ticket can be refunded without any fees by the original retailer.
Compensation: If you are travelling and experience a delay arriving to your destination due to a cancelled or delayed service, you may be able to claim compensation from the train operating company you are travelling with.
Delay Repay is a scheme used by all rail operators excluding Chiltern Railways that makes it easier for you to get compensation for delayed rail journeys. If you are delayed when you travel on a participating National Rail service, you can claim Delay Repay.
The delay is calculated against either the normal timetable, or an amended timetable that is published in advance (for example during planned engineering works at weekends) and it doesn’t matter what caused the delay, you can claim.
You can get more information about Delay Repay here.