SARS-CoV-2 is associated with various clinical outcomes, including asymptomatic infection, mild upper respiratory infection, severe lower respiratory infection manifested as pneumonia and respiratory failure, and in some cases, death.
Influenza is a contagious viral infection of the respiratory tract with transmission mainly through aerosolized droplets (ie coughing or sneezing) and usually peaks in the winter season. Symptoms generally appear within two days of exposure to an infected person and include headache, malaise, fever, chills, cough and sinus congestion, but also less common gastrointestinal symptoms (ie, nausea, vomiting, or diarrhea) mostly in children. Pneumonia can occur as a complication of influenza infection, causing increased morbidity and mortality in pediatric, elderly, and immunocompromised populations (e.g. patients being treated for conditions that reduce the strength of their immune system or with chronic lung disease).
Influenza viruses are classified into types A, B and C. Influenza A (Flu A) is the most common type of influenza virus in humans, generally responsible for seasonal influenza epidemics and potentially pandemics. Influenza A viruses are further classified into subtypes based on two surface proteins: hemagglutinin (H) and neuraminidase (N). Seasonal influenza is usually caused by subtypes H1, H2, H3, N1, and N2 of influenza A. Influenza A viruses can also infect animals such as birds, pigs and horses. Influenza B infections are generally limited to humans and are less often the cause of epidemics.
Respiratory syncytial virus (RSV) is composed of two strains (subgroups A and B) and causes an infectious disease that mainly affects infants, the elderly and immunocompromised persons. The virus can cause upper respiratory infections such as colds and lower respiratory infections that manifest as bronchiolitis and pneumonia. RSV remains the leading cause of hospitalizations in infants worldwide. Due to the fact that RSV infection develops only weak immunity, both children and adults can become infected again and again. Symptoms appear four to six days after infection and are usually self-limiting, lasting about one to two weeks in infants and about five days in adults. RSV season is usually flu-like, with infections starting to increase in the fall and lasting until early spring with symptoms consistent with a cold, such as a runny nose, fatigue, headache and fever.
The use of assays that provide rapid results to identify patients infected with these viruses can be an important factor in effective screening, appropriate treatment selection, and prevention of widespread outbreaks.
The procedure is simple, safe and painless. The possible existence of three viruses separately: Covid-19, influenza and RSV can be detected with only one nasopharyngeal swab, leading to differential diagnosis.