Have I got the flu or Covid-19?

The best card in the prevention pack for the winter is to get the flu vaccine

As the evenings begin to close in and a distinctly autumnal air prevails, the sense of a challenging winter ahead is difficult to ignore. For many patients, an ever-growing concern is being vocalised in conversations with their doctors: how will we know if our annual flu-like illness is influenza or Covid-19?

Get swabbed and have the PCR Covid test is the obvious answer. But the turnaround time on these tests is likely to lengthen as demand rises. And with false positive and false negative test results a fact of life, clinical judgement will be central to addressing the concerns of anxious patients and their relatives.

Listening, and listening even more, will be key. Speaking to Medscape, an online magazine for doctors, Dr Lewis Jay Kaplan, a critical care surgeon at the University of Pennsylvania, says every patient has a story, “and it’s up to you to figure out which chapter you’re in and how far along you happen to be”.

Each patient’s story can point to the correct clinical approach. We know that, traditionally, some 80 per cent of diagnoses are made by attentively listening to the patient, without any hands-on clinical examination. Following up with a series of questions about how the illness has impacted them, how their symptoms differ from the usual, and how they responded to treatment, will further refine the doctor’s assessment. A narrative based medicine approach such as this is especially useful as the majority of primary care consultations will be carried out via telemedicine.


The biggest challenge in the months ahead is the degree to which signs and symptoms between Covid-19 and the flu overlap. A fever, headache, muscle pain, cough, and fatigue are common to both.

A badly blocked and congested nose and sore throat are characteristic of the flu; shortness of breath and losing your sense of smell and/or taste point firmly towards Covid -19. Gastrointestinal symptoms such as diarrhoea occur in up to 40 per cent of novel coronavirus infection cases.

Chart comparing coronavirus, flu and and cold

But some people infected with Covid-19 have no symptoms, while others have mild symptoms. And the common cold – caused by a myriad of viruses including other strains of coronavirus – remains the most likely diagnosis if someone has a runny nose, a sore throat and a normal temperature. However, a major red flag and something not to be ignored, is the onset of breathlessness or difficulty breathing. Should this happen, seek urgent medical attention.

What about those unfortunate enough to be hit with the double whammy of overlapping influenza and Covid -19 infection? Early studies suggest about one in four Covid-19 patients have been diagnosed with an additional respiratory infection, including influenza. But researchers in Hong Kong and Japan have reported a reduction in influenza cases during Covid-19 outbreaks.

Preventing flu might make the Covid pandemic more manageable, and preventing coronavirus transmission might reduce the occurrence of flu as well, as witnessed in South Africa and Australia during the Southern Hemisphere’s just-completed winter period. And while it is possible the novel coronavirus is mutating into a less virulent strain, the evidence is anecdotal at best.

Interestingly, scientists who have tracked historical epidemics have found that outbreaks of respiratory viruses usually do not reach their peaks during the same time period. Though no-one knows exactly why this is, one study has postulated that temporary bursts of immunity to different viruses at a cellular level could be at play.

The best card in the prevention pack for the winter is to get the flu vaccine. This will help you escape flu or at least minimise it’s effects. It will also reduce the chances of contracting flu and Covid-19 simultaneously.

I truly believe a flu jab and a renewed zeal for hand washing and social distancing will make the winter ahead a bearable one.

Dr Muiris Houston at dotMD 2019, Bailey Allen Hall NUIG

by Muiris Houston
This article originally appeared in The Irish Times

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