Do You Have COVID, Flu A/B or RSV?
With the removal of pandemic measures and the arrival of the holiday season, various infections of the winter season have started to circulate alongside COVID-19. The simultaneous circulation of SARS-CoV-2, influenza viruses, and RSV is causing surges in infection rates and hospital admissions around the world. Thus, if you experience common respiratory symptoms such as coughing, sneezing, fever, runny nose, and fatigue, it may be more difficult than ever to tell which of these viruses you are most likely infected with. Read along to learn more about these infections and how to best differentiate them.
What is COVID-19?
COVID-19 is a highly infectious viral respiratory infection caused by SARS-CoV-2. Following the identification of the first known case in the Wuhan District of China in December 2019, the virus rapidly spread across the globe and led to the current COVID-19 pandemic. SARS-CoV-2 is an RNA virus of the coronavirus family, which also includes other well-known viruses such as SARS and MERS. SARS-CoV-2 can transmit via respiratory droplets, aerosols, and contact with contaminated surfaces. The symptoms and severity of the disease may vary depending on many factors, including the age, medical history, vaccination status, and the overall health of the infected person, as well as the strain of SARS-CoV-2 responsible for the infection. While common symptoms of COVID-19 include cough, fever, chills, congested or runny nose, loss of smell or taste, headaches, myalgia, and fatigue, a significant portion of infected people develop little to no symptoms. Even in asymptomatic individuals, however, the infection may remain contagious for up to 20 days. People with compromised immune systems and other health conditions are at higher risk of developing critical symptoms and complications such as respiratory failure, shock, and multiorgan dysfunction. Some people can also continue to experience symptoms for a prolonged period of time following recovery.
What is Influenza?
Flu is a common and highly transmissible respiratory infection caused by different types of influenza viruses. Influenza viruses are single-stranded segmented RNA viruses of the family Orthomyxoviridae. Among the different types of influenza viruses, Influenza A and B have been observed to cause clinically significant diseases in humans. Thanks to its excessive mutation rate and vast host range, influenza A viruses have been able to generate several pandemics throughout history, including the Spanish Flu, Asian Flu, Hong Kong Flu, Bird Flu, and Swine Flu. Likewise, influenza B has been known to account for significant epidemics. Although they are known to affect a variety of non-human animals, Influenza C and influenza D have never been observed to cause significant symptoms among humans.
Regardless of its type, influenza viruses transmit primarily through the respiratory droplets and secretions of infected people and cause respiratory symptoms such as fever, muscle pains, chills, sore throat, dry cough, runny or stuffy nose, and fatigue. Gastrointestinal symptoms such as nausea, vomiting, and diarrhea are less common and usually occur in children. The severity of influenza symptoms usually ranges from mild to moderate. However, individuals with low or compromised immunities, pregnant women, older adults, and young children can develop more severe symptoms and complications. Indeed, the World Health Organization (WHO) reports that influenza accounts for 3 to 5 million cases of severe disease and approximately 650,000 deaths every year.
What is Respiratory Syncytial Virus (RSV)?
Respiratory syncytial virus (RSV) is a single-stranded RNA virus of the family Pneumoviridae. Depending on the infected individual and affected area, infection with a respiratory syncytial virus (RSV) can lead to different levels and forms of disease ranging from mild upper respiratory disease to severe lower respiratory disease. Although the vast majority of healthy people bounce back shortly after suffering minor symptoms like a runny or stuffy nose, cough, fever, sore throat, headache, and sneezing, the virus can cause more severe illness in infants, older adults, and those with low or weakened immune, pulmonary, or cardiac systems. RSV is currently among the most common causes of lower respiratory tract illness in infants younger than 1 year of age. In rare cases, upper respiratory infection and bronchiolitis caused by infection with RSV can lead to life-threatening complications such as pneumonia, respiratory failure, and apnea.
How Can You Differentiate COVID-19, Flu A/B, and RSV?
COVID-19, influenza, and RSV are completely independent infections caused by different viruses. However, due to the large overlap among their clinical presentations, disease onset, and seasonal patterns, it may be difficult to distinguish which of these viruses you may be infected with. Still, there are slight differences that may give you an idea about the virus you are most likely infected with. Symptoms of COVID-19 can emerge 2 to 14 days after exposure to SARS-CoV-2 and may include fever, chills, cough, sore throat, runny or congested nose, loss of taste and smell, tiredness, headaches, and muscle pain. Symptoms of flu also commonly include fever, chills, cough, sore throat, runny nose, muscle pains, fatigue, and headache but it has a much more rapid onset of 1-2 days. While gastrointestinal symptoms are relatively uncommon for both COVID-19 and flu, children infected with influenza viruses are more likely to experience nausea, diarrhea, and vomiting. Among these infections, RSV often causes the mildest disease with symptoms such as sneezing, runny nose, cough, fever, wheezing, and decreased appetite.
Especially in the winter season when COVID-19, flu, and RSV are increasingly circulating together, the differential diagnosis of these infections requires the use of diagnostic tests. Thus, both laboratory-based nucleic acid detection tests such as PCR and rapid antigen tests are widely utilized in the detection and differentiation of SARS-CoV-2, influenza, RSV, and other respiratory viruses of the winter season. Our RapidFor™ SARS-CoV-2 Rapid Antigen Test Kits, Influenza A/B Rapid Test Kit, and RSV Rapid Test Kit provide a quick, convenient, and highly accurate method for the detection of these viruses in a flexible array of sample types. Multiplex assays such as our RapidFor™ SARS-CoV-2 & FLU A/B Antigen Combo Test Kit and SARS-CoV-2 + Flu A/B + RSV Combo Rapid Test Kit allow for the simultaneous detection and differentiation of infections with COVID-19, influenza, and RSV in minutes. Finally, rapid antibody tests such as our RapidFor™ SARS-CoV-2 Rapid IgG/IgM Test Kit and RapidFor™ SARS-CoV-2 Neutralizing Antibody Test Kit can help check for past COVID-19 infections and assess the level of vaccine-induced or infection-induced immunity against SARS-CoV-2.
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Jung, H. E., Kim, T. H., & Lee, H. K. (2020). Contribution of Dendritic Cells in Protective Immunity against Respiratory Syncytial Virus Infection. Viruses, 12(1), 102. https://doi.org/10.3390/v12010102