About half of all Covid-19 deaths appear to be happening in care homes in some European countries, according to early figures gathered by UK-based academics who are warning that the same effort must be put into fighting the virus in care homes as in the NHS.

Snapshot data from varying official sources shows that in Italy, Spain, France, Ireland and Belgium between 42% and 57% of deaths from the virus have been happening in homes, according to the report by academics based at the London School of Economics (LSE).

Published official data for care homes in England and Wales are believed to significantly underestimate deaths in the sector, with the Office for National Statistics only recording 20 coronavirus-related deaths in all care homes in the week ending 27 March. New figures are due out on Tuesday, but are unlikely to be up to date.

Last week the industry body Care England told the Guardian the total figure was probably approaching 1,000, with deaths reaching into double figures at numerous homes. Over the weekend details of more deaths emerged, including 13 residents who have died at the 71-capacity Stanley Park care home in County Durham, and there have reportedly been five deaths at Almond Court in Glasgow.

On Monday Prof Chris Whitty, the chief medical officer for England, said 13.5% of the UK’s care homes had a confirmed case of coronavirus among their residents, up from 9% last week, with 92 more homes detecting cases in the previous 24 hours.

But the spread of the virus and its lethality in care homes in five EU countries appears to be higher, according to academics who are calling for better UK data and a more urgent response to the crisis in care homes.

In its first review of early international evidence, researchers from the International Long Term Care Policy Network (LTCPN) found the most robust data was available in Ireland where, as of Saturday, 54% of deaths from coronavirus occurred in care homes, according to centralised government figures.

In Italy, a government survey covering deaths in 10% of the nations’ care homes suggested 45% of all deaths in that country could be in care homes, while central government data in France released at the weekend showed the same proportion of the 13,832 deaths in that country happened in care. In Belgium, health ministry figures showed 42% of Covid-19 deaths happened in care homes, and in Spain leaked regional government data suggested 57% of the country’s death toll from 8 March to 8 April was from care homes.

The figures came from different sources and the academics stressed that differences in testing availability and policies and approaches to recording deaths make international comparisons difficult.

But one of the report’s author’s, Adelina Comas-Herrera, of the LSE’s care policy and evaluation centre, said that given the fast-moving situation “we’re trying to document it as it happens and share it”.

“If we wait for perfect standards of evidence it will be too late to make any difference,” she said.

“To me it shows we will have to give equal resourcing in dealing with Covid between the NHS and social care. Care homes are places where physical distancing is almost impossible. It’s like a perfect storm: a susceptible population, not being able to implement the measures and the staff are not well supported and trained enough. Many of the staff are care assistants with very little medical knowledge.”

There have been three epidemiological studies of Covid-19 in care homes carried out by authorities in Seattle, one of which found that by 18 March, of 101 care home residents who contracted the virus in the preceding weeks, 34 died.

Dr Michael Head, a senior research fellow in global health at the University of Southampton, said the LCTPN’s summary of evidence “clearly shows the lack of focus on the elderly in care homes, despite their conclusion that care home residents may account for around half of Covid deaths in five European countries. Our elderly populations deserve better than to be ignored and forgotten.”

He cautioned that it remains hard to draw conclusions on precise numbers of deaths of elderly people in nursing and residential care around Europe and said that given there are few tests available, very few suspects cases will end up as confirmed cases.

He said: “Despite these limitations, we know that a range of infections can spread easily in vulnerable populations who live in nursing or residential care, for example norovirus, scabies, influenza, and here, the novel coronavirus.”

The Department of Health and Social Care said: “We are determined to give the social care sector the support it needs to respond to coronavirus and continue to work closely with Public Health England to monitor the impact on cares homes.

“We have published extensive guidance for care homes on admitting and caring for people during the outbreak, and have announced £2.9bn to help local authorities respond to pressures in key services, such as adult social care, and enhance the NHS discharge service, allowing patients to return home safely.”