SEQC Spanish Society of Laboratory Medicine

Figure 1. Vaccination against COVID-19

Within the framework of the XIX Conference of the Scientific Committee of the Spanish Society of Laboratory Medicine (SEQC^ML), which was held in virtual format from March 28-31, 2022, updates were provided on various topics of great interest. The available evidence onCOVID-19was analyzed and the role of the Clinical Laboratory in addressing it was described, as well as various topics related to the SARS-CoV-2 virus infection, in the course 'Update on COVID-19. And after the pandemic?

It is estimated that 10-15% of patients who have been infected by SARS-CoV-2 do not fully recover and develop persistent COVID (also known as Long COVID), which would represent around one millionaffectedpeople in Spain. This can affect anyone regardless of their age, sex or condition, although in general it affects patients who, in 50% of cases, are between the ages of 36 and 50, and female (79-80%).The majority did not have associated comorbidities prior to COVID-19.

The clinical guide for patient care for Long/persistent COVID, in whose writing the SEQC^ML collaborated, defines this condition as a multi-organ systemic complex that affects those patients who have suffered from COVID-19 and who remain with symptoms after the acute phase of the disease, up to 4 or even 12 weeks, with symptoms persisting over time.

As explained by Dr. Pilar Rodríguez Ledo, coordinator of the persistent COVID area of the Spanish Society of General and Family Physicians (SEMG), among the symptoms that generate the greatest disability are asthenia, headache, and myalgia, as well as the appearance of psychological and emotional symptoms. This multi-organ involvement - which can be expressed in 201 different symptoms - produces a serious disability in patients, which is seen most intensely in the work, family, and leisure areas in more than 70% of those affected.

For the correct approach to a disease with multiorgan involvement such as persistent COVID, a comprehensive approach is necessary counting on the participation of different specialties, including Laboratory Medicine, according to Dr. Luis García de Guadiana Romualdo, course coordinator and member of the SEQC^ML Commission on Biological MagnitudesRelated with Medical Emergencies. Thus, the initial exploration of the patient is completed with complementary tests, including laboratory tests.

Currently there are no specific laboratory diagnostic tests available for the diagnosis of Long COVID, but laboratory tests can be useful tools to rule out other possible diagnoses and organ-specific sequelae of a severe COVID-19 infection. In addition, markers such as KL-6 (Krebs von den Lungen 6) are being investigated to assess their usefulness in patients who develop post-COVID pulmonary fibrosis.

Regarding the causes of persistent COVID, in the absence of studies that provide evidence on its etiopathogenesis, Dr. Rodríguez notes that three mechanisms involved in it have been proposed.

First, due to the persistence of the virus in the body, the COVID infection causes a latent or chronic infection. Second, the acute infection could trigger an inflammatory storm or “cytokine storm” due to the complete virus or its fragments in its acute or confined phase. This event is an immunopathological characteristic of COVID-19 associated with the severity of the disease in its acute phase and the persistence of symptoms. And, finally, it could be due to an immune dysfunction generated by the development of COVID 19 autoantibodies that can act against immunomodulatory proteins and cause a deterioration of virological control. In addition, different studies also suggest the implication of diverse nutritional (omega 3, vitamin B12, vitamin D, among others), metabolic and microbiotaalterations associated with persistent COVID / Long COVID.

Immune response against SARS-CoV-2

The role of the immune response against SARS-CoV-2 was also analysed in the course. Specifically, Dr. Eva María Martínez Cáceres, Vice President of the Spanish Society of Immunology (SEI), addressed the role of specific immunity in the fight against COVID-19, probably a forgotten aspect in contrast to "antibody-centrism", a concept coined by some researchers to refer to the importance given to humoral immunity to the detriment of innate immunity.

Knowledge of this type of immunity and of the techniques for its evaluation will probably contribute to the improvement of vaccination strategies and allow the identification of those patients who require booster doses, thus contributing to the improvement of vaccine management.

Impact of the pandemic on laboratories

And what has COVID-19 meant for clinical laboratories? Dr. García de Guadiana assures that the pandemic has had a major impact on various aspects related to the organization of laboratories: the incorporation of new tests in the Emergency services, the high pressure to carry out diagnostic tests,and the reorganization of staff resources.

In addition, Laboratory Medicine has been able to "reinvent itself" to provide its activity in COVID-19 monographic hospitals such as the Nurse Isabel Zendal Emergency Hospital in Madrid or the COVID-19 Emergency Hospital in Seville.

Within the framework of the conference, Dr. José Ángel Noval, member of the SEQC^ML Committee on Point of CareLaboratory Testing, presented his personal experience in the implementation of a laboratory in a COVID-19 hospital and the importance of the Point of Care Testing methodology in it, as well as the possibility that the model could be a possible alternative solution to the traditional laboratory in future scenarios.