15.5% of Portuguese already have antibodies against the SARS-CoV-2 virus that causes Covid-19.
This has come from the second phase of the national serological inquiry (conducted by health institute Dr Ricardo Jorge) which has concluded that 13.5% is down to infection (meaning, the people who have tested positive for Covid and later recovered).
The highest prevalence for antibodies are in the regions of the north, Lisbon and Vale do Tejo, the centre and the Alentejo.
In relation to distribution of ages, antibodies have been found most in working adults, and least in the elderly aged between 70-79.
Among people who have already been vaccinated, the proportion of those with specific antibodies against SARS-CoV-2 was 74.9%, says the study, a number that increased to 98.5% when people who had received both shots within at least that last seven days were tested.
The institute warns that this data should be “interpreted carefully”, although it does appear to reinforce the “hoped for effect for an increase in populational immunity against SARS-CoV-2”.
This second phase of the national inquiry was developed and coordinated by the institute’s epidemiological and infectious diseases departments in partnership with the national association of clinical laboratories, the Portuguese association of clinical analysts and 33 units of the SNS (public health service).
Samples for the study were taken between February 2 and March 31, and involved 8,463 people resident in Portugal.
The first study, performed almost a year ago, concluded that only 2.9% of the population had developed antibodies against SARS-CoV-2. At the time, there were no differences between regions or age groups.