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from cases under investigation is an essential part of the management of COVID-19 and emerging infections in general. However, any shortage of laboratory diagnostic capacity at national or local level will hamper epidemic response. If countries need help in testing, a pool of specialised referral laboratories have offered support within the EU/EEA [82]. Member States should monitor the changes in the epidemic situation and be prepared to adjust the laboratory diagnostic capacity to the changing needs. Anticipating a rapid increase in the demand, countries should continue rolling out primary diagnostic testing capacity to local clinical and diagnostic laboratories. The specimen types to be collected are listed in the WHO laboratory guidance [83]. When the diagnostic laboratories have established their SARS-CoV-2 detection assays and confirmed their first five positive and ten negative detection results with the national SARS-CoV-2 reference or international referral laboratories [83], the diagnostic laboratories can confirm the test results by the secondary target gene in their own laboratory. In countries with limited transmission or local clusters, positive specimens should be subjected to confirmation by targeting a second gene of SARS-CoV-2 in an RT-PCR assay. In areas with local community transmission of COVID-19, detection by RT-PCR of a single discriminatory target is considered sufficient [83]. Confirmatory testing should be performed only for specimens where the first result is technically not interpretable or the RT-PCR cycle threshold value is above 35. In such a case, additional sampling or repeated testing and confirmation is advised. Serological assays are under development, and collecting serum specimens iat symptom onset, or at admission and at convalescent stage, or at discharge, will be useful for later seroepidemiological studies and should be done for hospitalised patients and during specific outbreaks such as in schools or confined facilities. Several commercial assays for SARS-CoV-2 are on the market, however, information on their clinical performance is still limited. Validation of the commercial assays is an urgent priority that some laboratories have started to address. Influenza testing at least of hospitalised patients with severe acute respiratory infections (SARI) should be continued as long as local circulation of influenza continues in order to initiate early antiviral treatment of influenza-infected patients. The differential diagnostics are also key for isolation and contact tracing of COVID-19 cases. Sentinel virological surveillance of outpatients with acute respiratory infections/influenza-like illness (ARI/ILI) for the monitoring of COVID-19 is recommended, based on the existing surveillance of influenza (see Surveillance section). A subset of patients should be swabbed based on geographical and population distribution. At regular intervals, a representative batch of positive specimens should be sent to a reference/referral laboratory for confirmation and further characterisation in order to identify and follow up the evolutionary changes of the virus. Testing specimens from sentinel outpatient surveillance sites for COVID-19 should be continued for as long as possible. In case of any shortages of sampling materials, oropharyngeal and nasopharyngeal swabbing can be performed with one swab and combined for one diagnostic test. As per WHO biosafety guideline, non-propagative diagnostic laboratory work (for example, sequencing, nucleic acid amplification test [NAAT]) should be conducted at a facility using procedures equivalent to Biosafety Level 2 (BSL-2) and propagative work (for example, virus culture, isolation or neutralization assays) should be conducted at a containment laboratory with inward directional airflow (BSL-3). Patient specimens from suspected or confirmed cases should be transported as UN3373, ‘Biological Substance Category B’. Viral cultures or isolates should be transported as Category A, UN2814, ‘infectious substance, affecting humans’ [84]. Countries should provide training to laboratory staff in laboratory diagnosis of SARS-CoV-2 as rapid expansion of laboratory diagnostic capacity is needed. Shortages for laboratory testing for COVID-19 Based on a rapid, 24-hour turnaround survey on 4-5 March, to which 15 EU/EEA countries responded, the countries reported shortages on deliveries of swabbing material, plastic consumables, RNA extraction and RT-PCR reagents such as enzymes, primers, probes and positive control material. In addition, shortages of PPE such as respirators, surgical masks, gloves and disinfectants for laboratory use were reported. The primary reasons for shortages were production bottlenecks. Based on the information available and modelling of expected cases in Europe, laboratories should prepare themselves for critically increasing their testing volume. Shortages are not affecting only diagnostics of SARS-CoV-2 but also have an impact on other critical diagnostic testing for infectious diseases including screening for infectious pathogens for transplantation and beyond. Optimising testing for COVID-19 Countries across the EU/EEA might be in different scenarios, even within the same country, and testing approaches need to be adapted to the situation at national and local level. In scenarios 0 and 1,