Brussels will publish its contract with vaccine developer CureVac on Tuesday - but only MEPs will be allowed to view it.
Stella Kyriakides, the EU commissioner for health and food safety, tweeted on Monday that the agreement between the European Commission and the German pharmaceutical firm would be disclosed to European lawmakers.
It will be the first time details of any deal of this type will be viewed outside of the commission and the company, but calls for greater transparency on all of the EU's vaccine agreements are already growing.
Very little is actually known about the purchasing details, ranging from how much they cost and to what extent the pharmaceutical companies are responsible for any adverse side effects.
French MEP Pascal Canfin told Euronews that there are no grounds for not releasing the details of the commission's vaccine deals.
"Who is liable when and if there is a health problem? The private company or the member state? It's something that should be public. There is no reason to have confidentiality clauses on this one," Canfin said.
In December, a Belgian minister accidentally tweeted the price list of EU vaccines.
The case highlighted the lack of transparency on the financial aspects of the deals and is something that could severely weaken public trust according to Jonathan Cushing from Transparency International.
"Adding transparency to that will help build confidence to show the money is being used effectively in the public interest. Huge sums of money are going into the COVID response and this should become eventually the embedded norm, by doing so, we can help build trust in the vaccines and in pharmaceuticals," Cushing told Euronews.
But as well as Kyriakides announcement on the CureVac contract, an EU Commission spokesperson committed Monday to work towards improving vaccine transparency.
"The commission has always said that it wants to be as transparent possible within the [vaccine] framework that is the one under which we are negotiating the contracts with the vaccine developers, with the pharmaceutical companies. And we are working on this, to make progress on that and if there are developments in this regard, we will make announcements as soon as possible," Eric Mamer told reporters.