The union body is demanding ministers stop turning a blind eye to “serious public health failure” and deliver decent sick pay for all workers.

From today, people with Covid-19 in England can end their self-isolation after five full days, as long as they test negative on day five and day six. People who are still positive on their rapid lateral flow tests must stay in isolation until they have had two consecutive negative tests taken on separate days.

The government says the decision was made after careful consideration of modelling from the UK Health Security Agency and to support essential public services and workforces over the winter.

But the TUC says reducing the self-isolation period won’t fix the UK’s fundamental sick pay problem. The union says that without decent sick pay available to all, our self-isolation system will fail – pointing out that workers on low or no sick pay face the impossible choice of self-isolating and facing hardship or putting food on the table but potentially spreading the virus.

The warning comes as the union body published new analysis which estimates about a quarter of a million private sector workers (267,800) were self-isolating without decent sick pay or any sick pay at all in mid-December. About 209,900 workers had to rely on statutory sick pay, which at £96.35 a week, is too low to meet basic living costs; while 57,900 got no sick pay at all.

The analysis is based on Office for National Statistics (ONS) data which estimates that 2.7% of the private sector workforce – around 723,900 workers – were off work with Covid-19 from 13 to 26 December as the Omicron variant swept across the country.

According to TUC polling conducted by Britain Thinks, about three in 10 private sector workers rely on statutory sick pay, and just under one in 10 get nothing. This leaves more than a third of private sector workers without decent sick pay or any sick pay at all.

The UK has the least generous statutory sick pay in Europe, worth just £96.35 per week – around 15% of average earnings, compared to an OECD average of more than 60%. And it is only available to employees earning £120 per week or more – meaning two million workers nationwide, mostly women, do not qualify.

The TUC has also warned employers that cutting sick pay for unvaccinated staff is no way to encourage vaccination, following announcements from Ikea, Wessex Water and Next that unvaccinated workers will have their sick pay cut, and instead have to rely on statutory sick pay.

Frances O’Grady, TUC general secretary, said: “No one should be forced to choose between doing the right thing and self-isolating or putting food on the table. But that was exactly the choice facing a quarter of a million private sector workers last month, as the Omicron variant raged across the country. This is a serious public health failure.

“It beggars belief that two years into the pandemic, statutory sick pay is still too little to live on and two million workers can’t get any sick pay at all. Ministers can’t continue to turn a blind eye to this vital public health tool. We need decent sick pay – paid at the real Living Wage – available to everyone.

“Unions have been encouraging everyone to get vaccinated and boosted. But cutting sick pay is no way to encourage workers to get the jab. And it would be an own goal for public health too, risking further transmission of the virus.”