Germany is carrying out Europe’s first large-scale coronavirus antibody testing to help assess infection rates and monitor the spread of the virus.
Antibodies in the blood are an indication that someone has had the virus. The theory is that those people will have at least some level of immunity, although there is no guarantee of full immunity or how long it would last.
The research will involve blood donations in four regions of the country where there have been large outbreaks of the virus, as well as a representative study of the broader population.
One doctor involved in testing for antibodies is Ulrike Leimer-Lipke.
"For these antibodies test to make sense, you must have had symptoms about four weeks beforehand," she explained. "Antibodies take a relatively long time to appear. If you only had symptoms last week, you wouldn't have antibodies by now.
"We know that, especially in Germany, a lot of people already had it. And it is also very important for them, especially if they have a grandmother, mother or father whom they look after, to know whether they are already immune."
Since the outbreak began Germany has effectively led the way in testing for coronavirus.
One of the worst affected regions of Italy is also looking to mass-testing as a way out of lockdown. Veneto is producing 20,000 swabs a day after supplies of commercial ones became more difficult to obtain. So far over 200,000 samples have been analysed.