A carer who was unable to be tested for coronavirus until July said she feared she may have spread the disease into care homes despite showing no symptoms.
Alison Taylor, from Sheffield, recently tested positive for antibodies indicating she once had coronavirus.
She now fears she may have worked while contagious and even visited her mother, who later died with suspected Covid-19.
The Department of Health and Social Care said protecting staff and residents at homes was a top priority.
Miss Taylor, 51, said: “I find it really hard to think that I might have passed it to care homes, to residents, to my family.
“I could be responsible for other people’s deaths without knowing.”
As a health care assistant, she has looked after vulnerable people throughout the pandemic.
Miss Taylor, who is employed by an agency, worked at four different homes before regular testing was introduced for care workers and residents without symptoms.
She said she was first tested for coronavirus about a month ago and has since had two tests in the past two weeks.
Last week, Miss Taylor had an antibody test that returned a positive result which, according to NHS England, meant she has had the virus.
She said if she had any idea she had been infected then she would have stayed at home rather than going to work.
Miss Taylor said: “I’ve continued working throughout with no symptoms so I don’t know if I’ve passed it on or not.
“I’m really uncomfortable that I could have gone into care homes, worked with however many residents and staff without knowing that I’ve got Covid.”
During the period when she might have been self-isolating, Miss Taylor went to the supermarket and visited her vulnerable parents.
She said she last saw her 82-year-old mother, who had Alzheimer’s disease, just before mother’s day, in March.
Miss Taylor said her mother was “really good” at the time but died less than a month later on 16 April.
She was never tested so there was no way of knowing whether she had coronavirus.
Miss Taylor said she was told coronavirus started in the home after a resident was treated in hospital for a fall.
She added: “Now I know that I’ve had it and I saw my mum, I’ve got some sort of guilt maybe, because I just don’t know.
“I’ve got a fear that I’ve passed it on to my mum maybe, to people that I’ve been caring for in my work place, with no idea whatsoever that I’ve been positive.”
At the start of the pandemic, health care workers reported difficulties with getting tested for coronavirus.
Routine testing for care home workers and residents was announced on 3 July.
However, the government has admitted regular testing would only reach all homes for over-65s and those with dementia by 7 September.
Miss Taylor said: “We need to know that staff are safe and that residents are as safe as they can be.
“If we’re not tested and we don’t know who’s got it, who’s had it, it’s just going to continue, it’s just going to roll on.”
Last week, the Department of Health and Social Care said a “combination of issues” had limited the number of testing kits available for care homes and as a result it had been unable “do as much asymptomatic testing as we want”.
A spokesperson has now added: “Protecting care home residents and staff has been one of our top priorities throughout this unprecedented pandemic.
“We are doing all we can to ensure tests are available to everyone who needs one. We are issuing at least 50,000 tests every day to care homes across the country, while working around the clock to minimise any disruption to routine retesting.”