Household size posited to be negative factor in Ireland’s efforts to reduce virus spread

Ireland’s larger than average household size is a contributing factor undermining efforts to reduce spread of Covid-19, according to data analysis by an Irish mathematical scientist.

However, other experts dispute household size as a major contributing factor to the pandemic in this country.

Examination of Eurostat data on household composition across Europe shows that Ireland is above the EU average in terms of the number of people per household, according to Dr Paul Dempsey (PhD), who has developed modelling predictions based on the data. 

Ireland’s average household size is 2.6 while the EU average is 2.3. Our household size is impacting our ability to limit virus transmission, he argued, as household transmission is a significant factor in spread of the virus.

“I came across the Eurostat data on household composition and how many people of what type of age were living in households, on average. I went into that and it explained why some countries can have less restrictive rules socially than others without having to worry about things going completely awry,” he determined.

The secondary attack rate of Covid-19, defined as the probability that an infected individual will transmit the disease to a susceptible individual.

The adult to adult secondary attack rate within households from could be as high as 44 per cent, according to an Israeli study, Dr Dempsey noted.

“It makes it harder on some countries because their houses can remain active spots for longer because there are more people to infect in them…It’s easier to spread the virus in a bigger household than in one that is small,” said Dr Dempsey.

Acknowledging that he is a scientist with no medical background, Dr Dempsey stressed that any successful response to tackling Covid-19 must be multifaceted. 

Prof Gerry Killeen, AXA Research Chair in Applied Pathogen Ecology at University College Cork (UCC) School of Biological, Earth and Environmental Sciences, said that larger, multigenerational households can make suppression of the virus more difficult.

Irish public health consultant and epidemiologist Dr Niall Conroy, who is based in Australia, disagreed with Dr Dempsey’s modelling.

“It’s less about the household size. It’s to do with density. Crowded living conditions are 100 per cent a factor in the spread of Covid,” said Dr Conroy.

“Ireland’s being 0.3 people above a European average doesn’t strike me as being all that worrying. Intergenerational households are a very high risk, as they’re often crowded, often poorer and they have vulnerable elderly people living in them.

“I’d say Ireland is like anywhere else, we have parts of the country where conditions are crowded and others not. I’m just not sure we’re worse in that regard than the UK, France of Germany.