It is possible to test positive for both COVID-19 and influenza, or the flu, at the same time. This co-infection, informally called “flurona,” is not a new variant but a combination of two established respiratory infections.
The Possibility of Co-infection
Co-infection with influenza and SARS-CoV-2, the virus causing COVID-19, occurs because both are respiratory viruses capable of infecting cells within the same host. The human body can be susceptible to multiple pathogens simultaneously, particularly during periods when both viruses are circulating widely in the population. Infection with one virus can even increase susceptibility to another, as the immune system is already engaged in responding to the initial threat.
While co-infection might seem uncommon, it is a recognized medical event. Studies indicate varying co-infection rates; some reviews suggest it occurs in less than 1% of COVID-19 patients. However, other research shows co-infections with two or more viruses can be detected in a higher percentage of positive respiratory samples, particularly during peak seasons. This highlights the complex interplay between different viruses within the human respiratory system.
Symptoms and Potential Severity
The symptoms of COVID-19 and influenza can overlap considerably, making it challenging to distinguish between a single infection and a co-infection based on clinical signs alone. Common symptoms for both include fever, cough, fatigue, body aches, sore throat, and a runny or stuffy nose. A notable difference is that loss of taste or smell is more frequently associated with COVID-19, though it can also occur with the flu.
Co-infection with both viruses can lead to more severe illness compared to having only one infection. Research suggests patients with co-infections face increased odds of requiring invasive mechanical ventilation, increased ICU admission, and a higher risk of in-hospital mortality. The combined impact of both viruses can exacerbate lung damage and provoke heightened inflammatory responses, leading to worse outcomes.
Getting Diagnosed and Treated
Given the significant overlap in symptoms between COVID-19 and the flu, specific diagnostic tests are necessary to accurately identify which virus, or viruses, are present. Healthcare providers often use multiplex PCR tests, which can detect genetic material from SARS-CoV-2, influenza A, and influenza B from a single respiratory sample. These molecular tests offer higher accuracy than rapid antigen tests and can provide results within a few hours.
Upon diagnosis, treatment for co-infection involves supportive care, such as rest and hydration, to manage symptoms. Antiviral medications specific to each virus are also prescribed. For COVID-19, antiviral drugs like nirmatrelvir with ritonavir (Paxlovid) or molnupiravir (Lagevrio) are used, while oseltamivir (Tamiflu) is a common antiviral for influenza. It is safe to take antivirals for both infections concurrently, as they target different viral mechanisms. Early initiation of antiviral treatment is important for reducing the risk of severe illness.
Strategies for Prevention
Preventive measures are highly effective in reducing the risk of contracting both COVID-19 and the flu, or other respiratory viruses. Vaccination is a primary strategy; individuals should stay up-to-date with recommended COVID-19 vaccines and receive an annual flu shot. It is safe and effective to receive both vaccines during the same visit.
Other public health recommendations also play a role in prevention. Practicing hand hygiene, like frequent washing or using hand sanitizer, limits virus transmission. Wearing masks in crowded or indoor settings, especially when respiratory virus circulation is high, and avoiding close contact with sick individuals can further reduce exposure. These measures collectively contribute to protecting against both infections.