Britain could have been hit harder by Covid-19 than other European nations because the past two winter flu outbreaks have only been mild, according to a study.
Researchers say influenza kills the same groups of people as the coronavirus, with both illnesses posing the greatest danger to the elderly and those with underlying conditions.
Data showed a clear trend between less intense flu seasons and high coronavirus death rates, with Belgium having escaped lightly from flu but battered by Covid-19.
England has suffered the second-worst coronavirus death rate of the 32 European countries analysed, after enduring only mild flu seasons for the past two years.
Public Health England statistics show around 20,000 excess deaths – those of any cause that happen above average – occur from influenza each year.
But only 1,700 extra fatalities were recorded during the 2018/19 outbreak, said lead author Dr Chris Hope who claimed data showed the 2019/20 season was also ‘very mild’.
It means more than 30,000 people in England alone were alive at the start of the Covid-19 pandemic who would have been expected to die in the previous two flu seasons.
Dr Hope, a policy modelling expert, added these people are likely to have been predominantly elderly and in poor health – two known coronavirus risk factors.
Data from the statistical bodies shows nearly 90 per cent of all confirmed and suspected coronavirus victims in England and Wales have been over the age of 65.
The data was plotted on a graph to establish a ‘trend line’, to uncover any correlation between milder flu outbreaks and more coronavirus deaths
The study, yet to be published in an academic journal, used European Centre for Disease Prevention and Control data on the flu intensity for 32 European countries.
The EU body ranks flu intensity as a score of between one and four. The figure is based on how badly each country was hit by influenza.
Countries were then given a total score over the course of 35 weeks in both yearly outbreaks – and the average was then worked out and used for the research.
For example, England had a flu intensity of 23. Scotland had an average of 12, Wales 18 and Northern Ireland 29, according to Dr Hope’s calculations.
He also compared the Covid-19 death rates up to June 10 for the same countries, working out how many infected patients died for every 100,000 people.
The data was then plotted on a graph to establish a ‘trend line’, to uncover any correlation between milder flu outbreaks and more coronavirus deaths.
Results showed that more Covid-19 deaths have occurred in nations which have experienced fewer flu fatalities over the past two winters.
Belgium – which has had recorded Europe’s worst coronavirus death rate (84.2 per 100,000 people) – had the lowest flu intensity apart from Scotland.
The country’s coronavirus death rate was 36 per 100,000 above the trend line, bolstering the claims made by Dr Hope.
Scotland would be expected to have suffered some of the highest Covid-19 death rates in theory, because it had the mildest flu season score.
However, it fell slightly below the trend line for excess deaths. Dr Hope did not offer an explanation as to why Scotland fell below average.
There are a number of factors which could explain why Scotland did not fare as badly as Belgium in the Covid-19 crisis, including how the government handled it.
There were only six countries in the study that have actually fared worse than Scotland in the pandemic, data suggests.
England has been the second-hardest hit during the pandemic, with 65.5 deaths per 100,000, and it has had lower than average flu intensity seasons in recent years.
But its coronavirus death rate fell way above the trend line with more deaths than would be expected based on its flu severity.
Italy, France and Ireland were also hit badly by the pandemic, according to Dr Hope’s calculations – which he admitted had ‘shortcomings’ in their reliability.
And Sweden – which bucked the global trend and opted against a lockdown – had more Covid-19 deaths than expected given its mild flu outbreaks.
Dr Hope wrote that further trials were needed ‘to determine whether the relationship is as significant as this first analysis suggests’.
He said: ‘The paper does not seek to make judgments about whether individuals were fortunate or unfortunate with regard to flu or coronavirus.
‘It simply reports my initial statistical findings as a policy modeller regarding the apparent statistical relationship between flu-season severity and COVID-19 deaths.
‘The correlation with flu intensity can’t explain everything but it does appear to be significant, and there is a plausible causation theory. Surely that warrants further investigation.’
Dr Hope added further studies should probe what the five countries well above the trend line – Belgium, England, Italy, France and Ireland – have in common.
He said: ‘One possibility is particularly thorough reporting of Covid-19 deaths. Another is a possible lack of attention to care homes early on in the pandemic.
‘Another possibility is population density. Or it could just be random variation around the trend line, as is always present.’
Dr Hope admitted several weeks’ worth of flu data was missing for some countries, mostly over the Christmas and New Year period.
He also warned Covid-19 deaths were only recorded until June 10 and that ‘it is not clear that all countries have adopted the same procedures’ for registering fatalities.
Professor Paul Hunter, an infectious disease expert and professor in medicine at University of East Anglia, said the study design is not a reliable one.
It is known as an ‘ecological study’ which are ‘generally thought to be very poor quality of evidence’ due to flaws in the statistics, he said.
He told MailOnline: ‘This would not be considered to be serious research in any epidemiology journal. My negative view of this paper should not be taken to mean that I do not think this is an issue that is worthy of further research.
‘It is certainly plausible that a proportion of the Covid-19 deaths are in people who may have died in the previous year or so if they had caught influenza. I just think you cannot draw any reasonable conclusions from this one piece of work.
‘Association cannot be taken as causation. Is one causing the other or is something else driving both?’
The flu jab uptake in England for over 65s has hovered around the 72 per cent mark for the past three winters, figures show.
There have been calls to expand the free flu jab programme this year to those in the 50 to 65 category, which would require around 10million extra doses.
Labour leader Sir Keir Starmer has urged for all over-50s to receive a free flu vaccine to prevent a ‘perfect storm’ of a winter flu outbreak and a potential second Covid-19 wave.
The flu vaccine, which is re-designed every year to be specific to the strains of influenza expected to circulate that winter, would offer no protection against the SARS-CoV-2 virus, which causes Covid-19.
The point of vaccinating more people against the flu would be to ease the burden on the health service.
There are concerns flu may overwhelm NHS hospitals, which already face the threat of being struck by a resurgence of coronavirus later this year.
Plans to vaccinate more people against influenza are already being considered by ministers after government scientific advisers recommended it.