Covid and flu: differences and symptoms: how to recognize and distinguish them

A sick woman reading a book

A difficult winter is upon us, with theincrease in cases of flu in conjunction with the reactivation of the Covid-19 infection, still very active today, there are many questions. Let's try to answer.

How to distinguish Covid-19 and Influenza

For the uninitiated the distinction between Covid and flu it may seem easy. Different symptoms, different diseases, different courses, surely it will be easy for an expert to distinguish them. But no.

Rather, it's so hard to tell them apart, especially in the early stages, that even the World Health Organization had to dedicate an episode of its "Science in 5 minutes" format to this very issue, to ensure that healthcare professionals were adequately trained on the matter.

In general: the symptoms of Covid are "worse" (i.e. more intense) and involve the respiratory and gastrointestinal tracts more.

What are the symptoms in common between Influenza and Covid-19

They are various symptoms in common between the two diseases, which can therefore lead to an erroneous diagnosis or an erroneous perception of the disease by the patient.

  • Headache
  • Temperature
  • Muscular pains
  • Sporadic or persistent cough
  • Frequent sneezing

What are the symptoms of Covid that are not present in the flu

Until the first variants, one of the clearest symptoms of the Covid-19 infection was loss of taste or smell, sooner or later we all learned of some relative or friend who discovered that they had been infected with Covid precisely following the onset of these symptoms.

But already from Omicron, then continued with Cerberus and Gryphon, the series on this symptom has collapsed sharply taking it from a fairly frequent symptom to a rare symptom.

However, there are other more frequent symptoms that have a slightly different manifestation in Covid than in the flu

  • More intense sore throat
  • Gastrointestinal disorders such as
    • Threw up
    • Diarrhea
    • Bellyache
  • More marked respiratory complications

The symptoms of the Gryphon and Cerberus variants

Unlike the old Covid variants, as Omicron already did, the new variants they have different symptoms, which characterizes them with a definition less lethal and more paraflu, but more marked than the classic seasonal flu.

  • Nasal congestion
  • Sore throat
  • Severe headaches
  • Cough
  • Muscular pains
  • Temperature
  • Intestinal disorders
  • Abnormal heart rhythm
  • Respiratory complications

Therefore, swabs remain the most important tool to be able to distinguish the two infections without a shadow of a doubt.

Is it possible to have double contagion from Covid and Influenza?

Many have wondered about the issue, and it is precisely on this topic that the experts have been involved to investigate the matter further.

Historically we already know that double contagion is possible in the case of the flu, as it happens, even with a fair number of cases, that people get infected with multiple forms of flu even one after the other if the immune response to one does not cover the other.

This is why medicine has always pushed for annual flu vaccination, as the coverage associated with it allows you to expand the protection of the immune system on more forms of flu.

Such a case is, presumably, feasible even with the contagion from Covid-19, although statistically it is more unlikely.

For example, in the case of the flu, it can happen that one of the two forms of flu replaces the other bringing it to a "lighter" expression, as if they were in competition with each other.
It is not known whether double contagion from flu and Covid can proceed in the same way, but it is a hypothesis that Massimo Andreoni, of the Italian Infectious Diseases Society, fears as possible when asked if double contagion was possible.

Theoretically yes, but we don't know what the result is. There may also be an antagonistic effect, with one of the two pathologies causing the other to manifest itself in a less important world. It is a hypothesis that has been made, in the light of the very low circulation of the flu in the last two years. It could have been caused, as well as by the masks, by this phenomenon

Massimo Andreoni
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Written by Andrew Navarro
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