The variant has so far officially been detected in one resident – but tents are ongoing to analyse other positive results.
A total of 189 people from the buildings have been told to go into self-isolation, confirmed Mettmann district head Marcus Kowalczyk to DPA.
Food and other supplies are being provided for them by the Red Cross and other agencies.
All residents of the two high-rise houses have been tested for Covid-19.
Velbert, which has a population of around 85,000, lies north of Wuppertal, and about 20km north east of Düsseldorf.
In total, there have so far been 19 positive results back connected to four families in the two buildings. However, the Indian variant, which is considered particularly contagious, has been detected in only one case so far.
The results of the series of tests conducted on Sunday and Monday are expected later on Tuesday, according to Kowalczyk.
“However, it will take about seven days for the findings that are positive to then be tested for the Indian variant,” he said, adding that he could not yet say how long the residents would need to stay isolated.
A ‘worrying’ variant
The Covid-19 mutant B.1.617, newly classified as a cause for concern, has so far been detected in only a few samples in Germany, “but its proportion has been steadily increasing in recent weeks,” according to an Robert Koch Institute (RKI) report published last week.
So far, its share in the samples tested is less than two percent, according to the RKI.
The variant was first found in India, which is currently grappling with hundreds of thousands of new cases per day. In response Germany has put tight travel rules between the countries in place in late April.
The variant has been classified as “worrying” by the World Health Organization (WHO).
According to experts, it could be up to 50 percent more contagious than the British variant, which is still detected in the majority of cases in Germany.