The flu is an acute disease that affects the upper and/or lower respiratory system (nose, pharynx, larynx, bronchi) and it is caused by three types of RNA viruses, A, B and C. Type A or B viruses are the main cause influenza in humans, while cases of influenza C are rarely reported in humans. Symptoms of the flu usually include high fever, muscle and joint ache, headache, extreme fatigue, runny nose, sore throat, and cough. Symptoms usually arise 1-4 days after infection and can last for 2-7 days. Some of the complications that can occur, usually in high-risk groups, are pneumonia from the flu virus itself or from germs, mainly pneumococcus, dehydration, asthma attacks in people with bronchial asthma, chronic bronchitis, heart failure or complications from diabetes.

Respiratory Syncytial Virus (RSV) can cause respiratory tract infection in patients of all ages and it is the leading cause of lower respiratory tract infections during infancy and childhood. RSV invades the epithelial cells of the upper respiratory tract creating large clusters of cells. The necrosis of these clustered cells leads to inflammatory secretions and obstruction of the airway. Subsequently, the descent of the viruses into the lower respiratory tract can lead to swelling and contraction of the alveoli causing bronchiolitis and pneumonia, leading to severe respiratory disease requiring hospitalization. In most patients, mild to moderate infection is caused with symptoms similar to the common flu, making it difficult to distinguish between the infections of the respiratory tract.

SARS-CoV-2 is a new strain of the virus that can result in a variety of complications, ranging from a simple cold to severe acute respiratory syndrome type 2 (SARS), which rapidly spread worldwide, resulting in the declaration of a pandemic by the World Health Organisation (WHO), in March 2020.

These viruses are highly transmissible from human-to-human, through droplets of saliva and mucus during coughing, sneezing, speaking spreading the virus in the air. The gathering of a large number of people in small and closed spaces as well as the cold weather increase the possibility of their transmission to the community. The symptoms of the three infections are common, making it difficult to distinguish the virus that causes the disease.

This test allows qualitative detection between the two types of influenza A and B (Flu A / B), respiratory syncytial virus (RSV) and SARS-CoV-2 through Real Time RT-PCR in samples from nasal and pharyngeal smear taken by trained nurses in a specially designed area, on the ground floor of our premises.

The test principle is based on the amplification of highly conserved areas of M1-gene (Flu A/B), N-gene (RSV), the E- (Envelope) and N- (Nucleocapsid) genes of SARS-Cov-2, as well as the E-gene region common to all SARS-like coronaviruses (SARS-CoV, SARS-CoV- 2). The procedure starts with the extraction of nucleic acids from the sample, which is carried out automatically by four state-of-the-art extractors available in our laboratory, minimising the factor human error while maximising the sensitivity of the method. Subsequently, polymerase chain reaction takes place by highly trained molecular biologists of our laboratory, using multipliers manufactured by leading companies in molecular applications, such as QIAGEN and DNA technology. The presence of FluA, FluB, RSV and SARS-CoV-2 is detected by the increase in fluorescence observed during the reaction and each virus is detected in a different optical channel. Internal Process Control (IPC), which is added during RNA extraction, is detected in the same reaction as a labelled probe and allows the detection of RT-PCR inhibition by various agents. It also acts as a control by ensuring that viral RNA was isolated from the biological sample, thus preventing false negative results due to insufficient genetic material or improper sample transfer.

The intensity of the fluorescence corresponds the quantity of viral load detected by the real-time PCR amplifier and is present in the sample. The high sensitivity of the method can detect even the smallest viral load in the sample and accurately determine if an infection in a possible case is due to one of the viruses listed above, making it a valuable tool for the physician to provide the patient with specialized medical care.

The professionalism and ethics that distinguish our laboratory staff along with the advanced technologies and methods used in our laboratory, put us on the first line for the early detection of viral respiratory infections.