Ensuring laboratory and diagnostic process in the conditions of a pandemic of a koronavirusny infection is an important point which allows to organize fast and timely diagnostics of an infectious disease, and, therefore, expeditious identification of both sick, and contact persons that allows to carry out medical and anti-epidemic actions.
Today major importance for etiological diagnostics of COVID-19 has identification of virus RNA. In each health care system there is a certain list of the registered sets of instruments for diagnosis of reagents for this purpose. Now laboratory examination on SARS-CoV-2 RNA is recommended to be conducted to all patients, the SARS having signs.
If to talk about screening researches, then as those it is recommended to use the test for SARS-CoV-2 virus antigen definition in smears from a nasopharynx or a stomatopharynx by an immunochromatography method.
What requirements to material which goes to a research? As a main type of substrate for a laboratory research on RNA of a coronavirus serves material which is received at capture of a smear from a nasopharynx (the fence from two nasal courses is surely carried out) and a stomatopharynx. Such smears gather in one test tube for bigger concentration of a virus in the studied material.
Besides, if the patient has symptoms of a disease of the lower respiratory tracts and when receiving a negative take in smears from a mucous nasopharynx and a stomatopharynx, material from the lower respiratory tracts can be investigated in addition, namely: a phlegm (at its existence), the washing waters of bronchial tubes received at a bronkhoskopiya or carrying out trazeobronkhialny lavage), tracheal or nasopharyngeal aspirate. At the patients who are on IVL for the purpose of identification of SARS-CoV-2 RNA receiving and a research of contents of a trachea is recommended. Besides, as additional material for a research biopsy or autopsiyny material of lungs and other materials, such as whole blood of the patient or fecal masses can be used.
It is necessary to remember that material samples for a laboratory research should be considered potentially infected therefore during the work with them all requirements for treatment of materials of this kind have to be considered. Health workers who carry out a material intake for researches or transport tests in laboratory, have to be trained in practice of safe handling of dangerous biomaterial, strictly observe precautionary measures and use all necessary individual protection equipment. Transportation of samples is carried out with observance of all necessary requirements. Material handling for a laboratory research is possible on ice. The term of performance of a research on coronavirus RNA identification in laboratories of the medical organizations should not exceed two days from the moment of receiving biological material.
In some managements the attention to a possibility of carrying out differential diagnostics is paid for what in addition to a research on a koronavirusny infection conduct researches on causative agents of other respiratory infections: influenza viruses of type A and B, a respiratory and syncytial virus, parainfluenza viruses, rhinoviruses, adenoviruses and also carrying out bacteriological or PTsR-diagnostics on Streptococcus pneumoniae is recommended, to Haemophilus influenzae of type B, Legionella pneumophila and also on detection of other causative agents of bacterial respiratory infections. For express diagnostics rapid tests can be used.
Several words should be told about identification of antibodies. Identification of antibodies to SARS-CoV-2 has auxiliary value for diagnostics of the current infection and the basic for assessment of an immune response on the flowing or postponed koronavirusny infection. IgA begins to be formed and be found approximately from the second day from the beginning of a disease, reach peak in two weeks and remain a long time. IgM begin to come to light approximately in a week from the beginning of infection and can remain within two months and more. Approximately from third week or earlier IgG are defined. Feature of an immune response on COVID-19 is the small period of time between emergence of IgM and IgG, and sometimes and their simultaneous producing. For definition of existence of IgG it is recommended to use sets of reagents with quantitative definition of an antiserum capacity that will allow to estimate tension of immunity in dynamics and to make selection of potential donors of rekonvalestsentny plasma.