Fears are growing that coronavirus could be ripping through some of the poorest and most overcrowded parts of Britain’s cities as new research suggests cramped living conditions might be accelerating the spread of the virus.

Analysis by the New Policy Institute shows that even after allowing for the much higher infection rates in London, the top five most-crowded areas in the country have seen 70% more coronavirus cases than the five least-crowded, where better-off homeowners are likely to live in larger homes with spare bedrooms and more than one bathroom.

Coronavirus hotspots such as London, which has 16,011 cases, and Birmingham, which has 1,604 cases, both have pockets of extreme overcrowding. Just over 11% of homes in the capital and 9% of homes in Birmingham are classed as overcrowded – the two highest rates in the UK.

NPI director Peter Kenway said the research demonstrated that overcrowded neighbourhoods generated more Covid-19 infections than less-crowded areas, even after taking account of where the outbreak started, local deprivation and the passage of time. “Our models show that even when you allow for the obvious factors, there is still a heightened risk to overcrowded households, especially when you have older people living with younger people,” he said.

Professor Gabriel Scally, president of epidemiology at the Royal Society of Medicine, said he was enormously concerned that the virus was spreading through overcrowded housing because it passed easily between people living in close proximity and sharing facilities such as toilets and kitchens. “Houses in multiple occupation must be in the same category as care homes because of the sheer press of people,” he said. “I have no doubt that these kinds of overcrowded conditions are tremendously potent in spreading the virus.”

He added that lessons learned from the infectious disease outbreaks of the past were in danger of being forgotten. “The Victorians paid the price for housing people in fundamentally unsatisfactory, unhealthy places when cholera and typhoid came calling,” he said. “We’re now in an era of new novel diseases, which will just love the modern equivalent of Victorian slums, where people do not have enough space or, quite possibly, enough ventilation or sunlight.”

Scally called on the government to make empty hotel rooms available to sick people in overcrowded homes. “They could stay there for the time they need to self-isolate,” he said. Housing charity Shelter added that local authorities needed more help to keep overcrowded families safe. “Councils need increased funding and clear guidance on providing appropriate accommodation,” said Polly Neate, Shelter chief executive.

Pizza delivery driver Walid Alhusien lives with his wife and five children in a room just four metres square in Mitcham, south London. They have to share a bathroom and kitchen with four strangers. He fears what might happen if the virus strikes. “I can hear two of my neighbours coughing all the time,” he said. “It is really scary. I want to protect my family but what can I do?”

Facebook Twitter Pinterest Walid Alhusien with his wife and five children. They live in one room in a house of multi-occupation in south London, and share two mattresses. Photograph: Andy Hall/The Observer

They try to disinfect the toilet every time their children need to use it . “All five rooms are using one bathroom,” said Alhusien. “Sometimes it is really disgusting. I try to clean it before my children go but I cannot always do it.”

Alhusien, 46, is still going to work on his motorbike four days a week: “I feel guilty I am taking this risk. I know I could bring it into the house but I need the money. I have to look after my children’s needs.”

Care worker Yaya Ofori lives in a small room in another multi-occupied home in the same part of south London. She tries to keep her two children away from the toilet and kitchen, which they share with four other people. “One of my sons has a problem with his chest. His chest fills up and he can’t breathe for a bit. He needs to use an inhaler,” she said. “I am worried with all this going around because he is more at risk.”

Ofori, 43, had to stop caring for elderly people in their homes this week after she fell ill. “I got some symptoms so I stopped yesterday. But I can’t self-isolate in this house,” she said.

Mitcham MP Siobhain McDonagh said families living cheek by jowl in her constituency and elsewhere were at risk of explosive outbreaks. “Coronavirus will just rip through all these houses in multiple occupation, with families in every room, sharing kitchens, sharing bathrooms,” she said.

Coronavirus will just rip through all these houses in multiple occupation, with families in every room, sharing kitchens, sharing bathrooms Siobhain McDonagh, Mitcham MP

The NPI’s analysis indicates that families sharing overcrowded homes with vulnerable elderly relatives maybe playing an even bigger role in fuelling the outbreak. It found areas with a high proportion of over-70s sharing with younger families had almost three times the coronavirus cases of neighbourhoods where more elderly people lived in their own homes.

The Ministry of Housing, Communities and Local Government said protecting the vulnerable was a top priority. “We’ve given councils access to £1.6bn to help them during this national emergency, including for finding safe and suitable accommodation for families who need it,” said a spokesperson.

Aisha Malik did her best to shield her elderly parents when her husband returned home his shift in a nearby supermarket with coronavirus symptoms. But it was almost impossible because they share the same cramped house just outside Birmingham’s city centre. Malik, her husband and her two children squeeze into one bedroom every night while her parents sleep on the sofa downstairs. Her sister’s family cram into another bedroom and her siblings have to share beds elsewhere in the house.

“My mum and dad are old and vulnerable. They come under the high-risk category because they both suffer from diabetes and my dad’s got heart disease as well,” she said. “I was much more worried about them than myself or my husband.”

Their terraced house is severely overcrowded, like many in Ladywood in Birmingham. The constituency has the highest rate of overcrowding outside London, with 7,317 households lacking enough bedrooms. Birmingham also has one of the highest proportions of families sharing with elderly relatives in the country, with nearly 29,000 over-70s living with working-age households.

Malik, not her real name, is worried that however careful they all are, one of them might pass the virus on to her parents, who are in their 60s, especially as one of her brothers now has symptoms. “You are not meant to cross paths. You are meant to use different bathrooms when somebody comes down with it but that’s not possible here,” she said. “We are literally all living on top of each other – how can we stay safe?”

Ladywood MP Shabana Mahmood said the custom of large south-Asian families living with elderly relatives in sometimes overcrowded conditions could be contributing to what appears to be the disproportionate impact of the virus on the BAME population. “I have a horrible feeling that in the two weeks before we shut the schools down, when the virus was spreading unchecked, there were lots of cases of children passing it on to elders they live with,” she said.