PARIS, France (AP) — France has opened 400 investigations into networks providing fake COVID-19 health passes, the interior minister said Sunday, as virus-related hospitalisations rise sharply across the country.

The case of a woman with the virus who died in a Paris regional hospital after showing a false vaccine certificate has drawn attention in French media in recent days. The hospital’s intensive care chief said they would have given the woman immediate antibody treatment had they known that she wasn’t vaccinated.

Authorities have identified several thousand fake COVID-19 health passes in use around France, Interior Minister Gerald Darmanin said Sunday on RTL radio. He said some 400 investigations have been opened into peddling fake passes, including some “connected to health professionals.”

He didn’t say how many people have been arrested so far, or provide details.

The government is tightening the rules on the passes, required to enter all restaurants and a growing number of events and venues. To get one, people must show proof of full vaccination, a negative virus test less than 24 hours old, or recent recovery from COVID-19.

With more confirmed infections one day last week than at any point in the pandemic, France is accelerating efforts for booster shots in hopes that is enough to reduce pressure on hospitals. Half of French intensive care units are occupied by virus patients, some regions are again delaying non-urgent surgeries, and more than 100 people with the virus are dying every day.

The Government closed nightclubs and tightened social distancing measures, but is trying to avoid a new lockdown. Health Minister Olivier Veran told newspaper Le Parisien that while “the epidemic wave is violent,” there are signs the rise is starting to slow. He said 90 per cent of people over 65 have had booster shots so far.