BERLIN (Reuters) - Germany will have difficulties making use of all available COVID-19 vaccines in April, Chancellor Angela Merkel said in an interview with broadcaster ZDF on Friday. Once a 7-day coronavirus incidence of under 35 per 100,000 people is reached, further relaxations beyond the opening of shops may follow, she added. “For the next opening step after retail, we have to be careful whether we stay stable below 35,” Merkel said. “When we have opened up shops and we are ... stable below 35 for two weeks, then we can consider the next step.” The number of new daily infections in Germany has been falling, prompting some regional leaders to push for a timetable to ease the lockdown, which has been in place since mid-December. But concerns are growing about the impact of more infectious variants of the virus on case numbers.