In the first half of 2023, we achieved one of our company's most significant milestones to date when the analysis of breast cancer patient tissue samples using Aiforia’s software began at the Mayo Clinic Hospital in the US in March. During the spring, we made important openings in the clinical market in Europe and also won new preclinical customers. Our order book more than doubled year-on-year to over EUR 2.3 million. This growth reflects well the size of our clinical customer base, which is, on average, much larger than in the research sector. However, the new clinical clients in Europe are not yet reflected in the revenue for the period under review. We updated our revenue recognition practices to comply with the IFRS standard, and as a result, about a quarter of the comparable revenue for the period under review will be deferred to future periods.
I am very pleased with the development of our operations. Our chosen strategy to make the AI model development tool available also to our customers has been a significant advantage, creating new opportunities for us in both the preclinical and clinical markets. Some of our customers require ready-to-use certified and validated AI models that can be deployed rapidly. Others also value the ability to create and customize AI models to meet their own needs. We are proud to be able to serve both interests. We have also seen some interesting first research results on how tissue features identified using Aiforia’s software have been combined with patient follow-up databases to create predictive models that can influence patient care. It is great to see how our technology can be used to generate information that helps to choose the best possible treatment path for the patient.
Over the past six months, we have developed the technical features of the software that, among other things, allow for smoother integration into our customers' various information systems and speed up the implementation of the softwares. These improvements will allow us to offer a smoother and more efficient user experience to our customers.
The pathology sector is becoming increasingly digitalized, and our customers are actively looking for solutions to improve work efficiency. The market will open up rapidly in the coming years, and we need to be close to our customers to provide them with the right solutions. Business Finland's funding decision for a loan of up to EUR 7.3 million in April 2023 will help us bring our planned products to market faster and thus secure our position in an accelerating competitive environment.
We are still well on track to achieve our short-term goals set for the IPO by the end of 2023. At the end of the reporting period, we had five CE-IVD-marked AI models for clinical diagnostics and CE-IVD-marked viewer software, five clinical diagnostics accounts, ten large pharmaceutical accounts, and more than 5,000 users.
I would like to thank our staff, customers, and shareholders for the achievements of the first half of 2023. We will continue our work to advance AI-assisted tissue sample analysis so that every patient could receive an accurate diagnosis and the best possible care.