## 5 Conclusions  
This article presents an optimisation project, implementing Lean methodologies and Total Laboratory Automation (TLA) in the serology area of a microbiology laboratory. The Value-Stream Analysis (VSA) Lean technique was selected to map and analyse the serology workflow in the laboratory. Two process workflows were defined for analysis, the process followed by a HIV serological sample and the process for total nucleocapsid (COVT) and spike IgG (COVIDGG) SARS-CoV-2 antibody testing. Pre- and post-TLA scenarios were considered for VSA, measuring the main process KPIs affecting the diagnostic response time and laboratory costs. The process optimisation ideas identified in the pre-TLA Lean analysis were implemented and assessed in the post-TLA analysis. The results of HIV serologic samples in pre-TLA and post-TLA phases showed that HIV total process time increased its added value by 81% versus the former pre-TLA situation, where the tasks with added value accounted for only 14% of the total process time. The total process time or TPT decreased from pre- to post-TLA from 28:04:28 h to 00:45:55 h, processing the samples within a single 7 h working shift. For COVT-COVIDGG serology testing, the total process time decreased from 01:28:27 h to 01:24:30 h, which represented a reduction in time of 4.3%. Process layout, safety in the workplace and ergonomic conditions improved with the new workflow. Total process time added value increased by 4% in the post-TLA scenario for COVT-COVIDGG. Manual sample transports and unnecessary staff movements were minimised in the new automated serology line. In addition, manual technician tasks decreased by 32% with the TLA by automation of manual activities such as sample registration, identification, separation, re-racking and tube uncapping that were eliminated with the new pre-analytical equipment. This avoided biological, health and safety risks for laboratory personnel. TLA and Lean optimisation directly affected the serology process Turnaround Time (TAT), calculated as the time elapsed from the sample reception in the laboratory to the test results' validation. We could conclude that it decreased for all sample testing in the post-TLA scenario. The percentage of improvement from pre- to post-TLA was up to 87.3% and 19.3% for HIV and COVT-COVIDGG samples, respectively. The laboratory could perform and inform sample diagnosis within a working shift, improving their diagnostic response time to the patient. It was assessed that, in both HIV and COVID-19 process workflows, process-waiting times contributed more than 80% to TAT, mainly due to existing direct labour waiting times in the pre-analytical area and in the clinical results validation process. The waiting times reduced by 35.0% and 21.7%, respectively, in the post-TLAscenario with the implementation of the full automation and specific improvement actions, but they were not completely removed due to internal laboratory routines. The Lean optimisation and full laboratory automation also had a direct effect on the process and laboratory costs. The fulltime equivalent (FTE) count decreased by one microbiologist and one laboratory technician in the serology area, as they were relocated to other laboratory sections. This move bolstered the laboratory's capacity to undertake additional activities, such as sequencing. We anticipate a possible decrease in the number of laboratory technicians, which will evidently influence direct productivity. The implemented measures generated an estimated annual cost savings of EUR 15,212.22 for the two serology tests in the analysis, considering improvements in the main cost items (reagents, instrumentation, equipment and direct labour costs). Further savings could be assessed with the extended calculation for all routine serology testing integrated in the automation.