On 14 April 2021, the UK Office for National Statistics (ONS) issued a report that suggests 54% of the UK population had antibodies to Covid-19 by 28 March 2021. The comparable percentage in Switzerland could be around 25%, however there is no up to date data to indicate this.
Most of the antibodies detected in the UK are likely to be the result of vaccination. By 3 April 2021, 6 days after the date of the ONS antibody snapshot, 64% of the population had received at least one dose of vaccine, 10 percentage points higher than the 54% rate of antibodies.
The latest antibody estimates in Switzerland, which were completed between December 2020 and February 2021 estimated around 17% of the population had antibodies. Since then the virus has continued to spread – Switzerland has recorded around 176,000 (2%) cases since the end of 2020 – and an additional 6% of the population have had at least one dose of vaccine since mid February 2021, so the percentage with antibodies could possibly now be around 25%.
The ONS said that it is important to draw the distinction between testing positive for antibodies and having immunity. It is not yet known how having detectable antibodies, now or at some time in the past, affects the chance of getting Covid-19 again, since other parts of the immune system (T-cell response) will offer protection. It also stressed that the length of time antibodies remain at detectable levels in the blood is not fully known either.
The national studies underlying the UK report are based on SARS-CoV-2 antibody blood test results taken from a randomly selected subsample of individuals aged 16 years and over, excluding individuals in hospitals, care homes and other institutional settings.
ONS report (in English)