Study estimates 1.7% national prevalence of Covid-19 in Ireland

The study measured antibodies to SARS-CoV-2 virus, which are an indication of past infection with Covid-19
Study estimates 1.7% national prevalence of Covid-19 in Ireland
File image of a Covid-19 test. Picture: Marc O’Sullivan

Less than 2% of the Irish population has been infected with Covid-19, according to a new study.

The study was conducted by the Health Protection Surveillance Centre (HPSC) in June and July, and has today been published by the HSE.

It measured antibodies to the SARS-CoV-2 virus, which are an indication of past infection with Covid-19.

A representative sample of 1,733 people aged 12 to 69 years in Sligo and Dublin participated in the study, which is the first of its kind in Ireland.

Of the 1,733 samples tested, 33 tested positive for antibodies. 28 of these were in Dublin, and five in Sligo.

No statistical differences were identified in the prevalence by age group, or between males and females.

It found 0.6% of people in Sligo had been infected with the disease and 3.1% in Dublin.

Based on the results, the health service estimates a national prevalence rate of 1.7%.

The HSE said in a statement: “Of those who were found to have antibodies, 73% had symptoms that are included in the Irish Covid-19 case definition; that is, one or more of the following: fever, cough, shortness of breath, loss of sense of taste or loss of sense of smell.

“One third of all those who were found to have antibodies reported loss of sense of smell and/or taste.” 

The statement added: “Using the prevalence data from this study, the HPSC estimates that that 59,500 people in Ireland in the age group 12 to 69 years had been infected with SARS-CoV-2 up to mid-July; three times more than that detected via surveillance of notified cases.” Dr Derval Igoe, Principal Investigator for SCOPI at the HPSC said: “It is not surprising that a relatively low national seroprevalence of 1.7% was observed here.

“Other countries in Europe, such as Spain and Italy, where there has been a much more intense epidemic, have reported national seroprevalence estimates of 5% and 2.5% respectively.

This means that the vast majority of people living in Ireland had not been infected with SARS-CoV-2 virus by the time of the study.

“As a society, we need to continue with our public health measures, including physical distancing, respiratory etiquette, hand hygiene and the use of face coverings, until a vaccine for Covid-19 is available.”  

Dr Ronan Glynn, Acting Chief Medical Officer, added: “The low prevalence rate indicates that the measures put in place early, as well as the sensitive case surveillance, testing and contract tracing system, have been effective in minimising community transmission.” 

It comes as one further death and 136 new cases of Covid-19 were reported today.

Professor Philip Nolan, Chair of the NPHET Irish Epidemiological Modelling Advisory Group, said that the R-number is "now at or above 1.2".  

He said: "There are two concerns now, the number of new cases per day remains high and the pattern has changed from large outbreaks in specific settings to much smaller outbreaks widely distributed across the country.  

"The measures announced this week, asking us to stay apart, aim to suppress Covid-19 in the community."

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