BERLIN, June 15 (Xinhua) -- Germany's Minister of Health Karl Lauterbach expressed his concern Wednesday about the current increase in COVID-19 infections, warning that a summer wave has started.

       "The announced summer wave has unfortunately become a reality. This also means little relief for the next few weeks," Lauterbach told the Rheinische Post newspaper.

       The nationwide seven-day incidence rate per 100,000 inhabitants rose to 472.4 on Wednesday, almost twice as high as a week ago, according to the Robert Koch Institute (RKI) for infectious diseases.

       For the first time since April, daily COVID-19 infections in Germany exceeded 100,000 on Tuesday, according to the RKI.

       The new surge is largely attributed to the two more contagious Omicron subvariants, BA.5 and BA.4. Within a week, the share of BA.5 in Germany doubled to 10 percent, according to the RKI's latest weekly report.

       Lauterbach encouraged the elderly and vulnerable people to take booster vaccinations, which can prevent severe symptoms even if they do not necessarily prevent infections.

       Of the 69.4 million adults in Germany aged 18 and above, around 85 percent are vaccinated against COVID-19. More than 69 percent have received one booster shot while 7.8 percent already received two, according to official figures.

       Most COVID-19 restrictions in Germany have been lifted. It was one of the last countries in the European Union (EU) to drop travel restrictions when entering from another EU member state for the summer months.