POCT
Clarissa Chan, PharmD
With so many similarities in symptoms for both COVID-19 and influenza, misdiagnoses can occur when infection is not confirmed by a laboratory test. Community pharmacies are positioned as the front line of defense when patients present with flu-like or COVID-19 symptoms. An increasing number of diagnostic tests used in community pharmacies are able to detect the presence of COVID-19 or influenza viruses, in some cases with just a single sample.
Although last year’s flu season was virtually non-existent due to wide-scale social distancing, experts hypothesize a resurgence of the flu this fall due to a variety of factors including children returning to in-person school, declining use of masks, and lack of immune response to the flu this past year. From a public health standpoint, it will be important to identify and treat people efficiently.
Using a multiplex assay that tests for both viruses can save testing materials and provide faster results for some patients. More states are beginning to authorize pharmacists to administer both tests individually or together in one assay.
Frequently asked questions
Is it possible to be infected with COVID-19 and one or both influenza A or B viruses at the same time?
Yes, co-infection can occur with both COVID-19 and flu. Positive tests for both SARS-CoV-2 and one or both seasonal influenza (A and/or B) viruses means that nucleic acid or RNA specifically from these viruses is detected. These test results should always be interpreted based on clinical findings and observations to determine diagnosis and treatment.
How long is an infected patient able to spread the COVID-19 or influenza virus?
People may be concerned about a previous exposure to COVID-19 or influenza for themselves or family members. Knowing how long it has been since a person was exposed can provide clues as to which virus they may have contracted and which test to use.
Most people with the flu are contagious for about 1 day before they show symptoms. For COVID-19, though, it is possible for people to spread the virus for about 2 days (or possibly earlier) before experiencing any signs or symptoms and remain contagious for at least 10 days after signs or symptoms first appeared.
Which virus is more contagious?
While the COVID-19 and influenza viruses both spread from person-to-person between people who are in close contact (within about 6 feet), the virus that causes COVID-19 is generally more contagious than an influenza virus.
Also, the COVID-19 virus can spread quicker and easier to a lot of people at the same time, and it is more likely than influenza to continue spreading as time progresses.
Who should get tested?
While caused by two different viruses, both COVID-19 and influenza can present with similar symptoms such as fever, cough, and shortness of breath. CDC recommends testing for COVID-19 in any symptomatic patients and some at-risk populations exposed to the virus.
When determining the right test, keep in mind that symptoms can take longer to present in COVID-19 patients. Typically, a person experiences symptoms anywhere from 1 to 4 days after infection with influenza, while COVID-19 symptoms may not appear until up to 14 days after infection.
Should someone be tested even if they are asymptomatic?
Maybe. Asymptomatic and pre-symptomatic patients can be tested if they have respiratory symptoms consistent with COVID-19, especially when they have been in close contact with someone who is known to be infected or in a geographic area with a high level of COVID-19 infection.
While tests are highly accurate, a negative test result should not be used by itself to rule out exposure and infection with SARS-CoV-2, influenza A, and/or influenza B viruses, or to determine whether an individual may be contagious.
What should my patients expect with testing?
Most commercially available multiplex assays that test for influenza, COVID-19, or both require a sample collected through a simple nasopharyngeal swab.
Other sample collection methods may include nasal aspirate, nasal wash, throat swab, and bronchoalveolar lavage fluid. Depending on the testing device used, patients can expect test results in as little as 15 minutes in some cases, while other tests take up to 8 hours.