it's a mistake (often a deliberate one to treat the EU as a monolith group
However it was the EU gave out   the invites to join the PPE and ventilator purchase group
From European Commission
DG Health and Food Safety website

The joint procurement of medical countermeasures is included as an article in the 2013 decision on serious cross-border threats to health. As an implementing action of this Decision, the Joint Procurement Agreement (JPA) was adopted on 10 April 2014. To date, the JPA has been signed by 23 EU countries. The Commission launched the procedure to prepare an agreement for the joint procurement of vaccines in the case of a future pandemic.
The JPA enables countries to procure pandemic vaccines and other medical countermeasures and equipment as a group, rather than individually. Through the JPA, any EU country can make a proposal to others to procure medical countermeasures together. A minimum of four Member States, with agreement from the Commission, is needed to launch a joint procurement procedure.