The number of people infected with Covid-19 by each carrier had risen from about 0.7 to 0.96 since the country began lifting restrictions on 20 April, said Lothar Wieler, the head of the Robert Koch Institute.
Although that number means the epidemic is still under control, it gives the German government little leeway to remove more restrictions as the figure, which is also known as the reproduction number, must remain at or below 1.0 to contain the virus.
Mr Wieler urged the public to continue to abide by social distancing rules, including wearing masks while on public transportation or shopping.
“We want to continue to defend this success, and we can do it if we follow certain rules,” he said at a news conference on Tuesday.
“We do not want the health system to be overwhelmed, and we do not want many people to die from Covid-19.”
Germany allowed small businesses to open earlier this month and the country’s 16 states have introduced varying rules on wearing face masks in public, with the use of cloth masks now mandatory on public transport and, in most regions, in shops.
The country has been viewed as one of Europe’s most successful in tackling the coronavirus pandemic, thanks to widespread testing, and has recorded a significantly lower death toll than other countries such as Italy, Spain and the UK.
Health officials reported 1,304 new cases in Germany on Wednesday – an increase on the past two days.
However, Professor Paul Hunter, a professor in medicine at the University of East Anglia, suggested it was too early to say if there had been a major increase in cases following the relaxation of restrictions.
“Despite suggestions that cases of Covid-19 have started to increase again in Germany following relaxation of its lockdown measures, this does not appear to be the case,” Professor Hunter said, arguing that the rise in cases earlier this week was “almost certainly” due to testing levels dropping over the weekend.
“Rather than look at individual days and make inaccurate conclusions, it is always better to look at the smoothed data.”
He said the “underlying trend” of cases in Germany was still coming down on Wednesday.
Angela Merkel, Germany’s chancellor, has urged caution in the easing of the country’s lockdown amid concerns about a second wave of infections.
“Even if we assume that one person infects 1.1 others, we would reach the limits of what our health system and intensive care beds can manage in October,” Ms Merkel said earlier this month.
“If we assume a rate of 1.2... we would reach the health system’s limit in July. And with a rate of 1.3 – it doesn’t sound like much – we would get there in June already.”
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