Influenza is an acute respiratory disease that is caused by influenza viruses, usually subtypes of influenza A or B. COVID-19 is caused by a coronavirus infection (called SARS-CoV-2).

It is understood that COVID-19 and flu viruses reproduce in similar ways. Both COVID-19 and influenza may have no symptoms (asymptomatic) to severe symptoms. Typical COVID-19 and flu symptoms include fever, cough, trouble breathing, sore throat, runny or stuffy nose, headache, myalgia (muscle pain), nausea, vomiting ,and diarrhea. Loss of taste or smell may be additional symptoms of COVID-19.

In case of influenza, symptoms normally progress anywhere from 1 to 4 days after infection. During the first 3-4 days, older children and adults with influenza appear to be the most contagious. In COVID- 19, a person develops symptoms as early as 2 days  or as late as 14 days after infection and the time period can differ. It is possible to remain infectious for at least 10 days after testing positive for COVID-19 whether anyone is asymptomatic, or their symptoms go away.

COVID-19 is more contagious than influenza. It has also been shown that COVID-19 has more super-spreading events than influenza. This implies that the COVID-19 virus will spread to many individuals rapidly and easily. In both COVID-19 and influenza disease, complications may develop. Among those at the greatest risk are older adults, people with some underlying medical conditions and pregnant women. There are several FDA-licensed influenza vaccines developed annually to protect against the 3 or 4 flu viruses that scientists believe to circulate each year.

There is currently no vaccine to prevent COVID-19. Influenza ( flu) vaccinations cause antibody development in the body approximately two weeks after vaccination. These antibodies protect against viral infection. The United States Centers for Disease Control and Prevention ( CDC) tracks influenza virus isolates internationally in collaboration with the World Health Organization (WHO) and its tracking network to monitor the activity of the disease. The normal trends of influenza activity in the United States is shown in the table.


In the fall and winter, the flu season occurs in the United States. Although influenza viruses circulate year-round, between December and February, flu activity peaks most of the time, but activity can last as late as May.

To detect influenza viruses in respiratory specimens, there are a variety of flu tests available. Rapid influenza diagnostic tests (RIDTs) are the most common. RIDTs function by identifying the parts of the virus that activate an immune response (antigens). In about 10-15 minutes, these tests will provide results. At MCI Diagnostic Center, BD Veritor System is used for the rapid detection of Flu A +B.The BD Veritor System for Rapid Detection of Flu A+B is a chromatographic immunoassay to detect influenza A and B viral antigens in samples processed from respiratory specimens.

MCI Diagnostic Center is also doing RT-PCR ( REVERSE TRANSCRIPTION POLYMERASE CHAIN REACTION)-“gold standard” test for diagnostic detection of SARS-CoV-2.  Besides RT-PCR, MCI is doing rapid antigen tests for SARS-COV-2 in symptomatic patients. Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) ( Coronavirus disease (COVID-19) antibody test is also performed from blood to assess the immune response to the virus.