I assume you mean Article 5, and no, yes, maybe, but probably no.
Article 5's requirement is that the members convene to discuss a response to an attack, not an obligation to attack.
Furthermore, this sounds more like an even dumber dumb Watergate, but with arguably, a moral justification i.e. covert burglary, maybe even armed robbery, for vaccines contracted to the UK.
Article 42.7 of the EU Charta would also apply and is a bit more direct:
If a Member State is the victim of armed aggression on its territory, the other Member States
shall have towards it an obligation of aid and assistance by all the means in their power
It is not armed robbery when the military is sent to another country. war is ultimately always about ressources, so you could argue every war to just be an armed robbery gone wrong.
If someone sends their military to another coubtry without this countries explicit consent it is an act of war.
You can semantically argue anything you want, but ultimately I can't imagine any scenario where this would have been an actual war, or even resembling one.
If the goal was to seize assets contained within a one, or just several buildings, the most likely way this would have played out would have been covert foreign intelligence teams, not an SAS commando raid with a bodycount.
Would it have been incredibly dumb, and probably end up with the intelligence officers/assets arrested? Sure.
Would it have been anything like a HVT snatch and grab in Afghanistan? No. Just no.
Article 5 has been invoked once, the US invoked it during 9/11. They asked for some extra air reconnaissance around the middle east, and basically to have allies be ready for joint action that never materialized. Article 5 is not an immediate declaration of war or anything.