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Adenovirus, flu or COVID-19?

Select symptoms and see what the CDC and the Russian Ministry of Health clinical guidelines say about each infection. This is not a diagnosis but a reference with sources.

Select symptoms

Choose one or more symptoms: the table will show what the sources say about them.

SymptomAdenovirusFluCOVID-19
Feveroccurs [1]occurs [2]occurs [2]
Fever above 38 °C (100.4 °F) for more than 3 daystypical up to 5–7 days [3]typical up to 5–7 days [3]no data
Sore throatoccurs [1]occurs [2]occurs [2]
Coughoccurs [4]occurs [2]occurs [2]
Runny or stuffy noseoccurs [4]occurs [2]occurs [2]
Red eyes, pink eyetypical [1] [3]not among typical symptoms [2]not among typical symptoms [2]
Swollen lymph nodestypical [4]not among typical symptoms [2]not among typical symptoms [2]
Vomiting, diarrheaoccurs [1]occurs diarrhea more common in children [2]occurs [2]
Loss of taste or smellnot among typical symptoms [1]occurs [2]typical more common with COVID-19 [2]
Muscle pain, body achesoccurs [4]occurs [2]occurs [2]
Shortness of breathno data pneumonia is among its possible manifestations [1]occurs [2]occurs [2]

Typical — the source highlights the symptom as a distinctive feature of the infection. Occurs — the symptom is on the list of symptoms. Not among typical symptoms — the source does not name it among the usual symptoms; this does not mean it never happens.

Key differences

AdenovirusFluCOVID-19
Causea DNA virus without an envelope [5]an RNA influenza virus [3]the RNA coronavirus SARS-CoV-2 [3]
When symptoms appearfor respiratory viral infections in general, 1–14 days after infection [4]after 1–4 days [2]after 2–5 days, sometimes up to 14 [2]
How long contagiouspeaks on day 3 after infection, low-level for up to 2 weeks [3]from a day before symptoms; most contagious in the first 3 days of illness [2]on average about 8 days from symptom onset [2]
Specific antiviralsnone approved [1]available, prescribed by a doctor [3]no data in our sources

You can't tell them apart by symptoms

Flu and COVID-19 symptoms are often the same, and only a test can confirm the diagnosis [2]. The same goes for adenovirus: it is detected with a rapid test or a PCR swab [3].

This page does not make a diagnosis. If you notice warning signs, see a doctor: list for children, for adults.

How testing worksAll adenovirus symptoms

Sources

  1. CDC (US Centers for Disease Control and Prevention). About Adenovirus. Updated December 16, 2025. Accessed October 7, 2026.
  2. CDC (US Centers for Disease Control and Prevention). Similarities and Differences between Flu and COVID-19. Updated September 17, 2024. Accessed October 9, 2026.
  3. Russian Ministry of Health, Union of Pediatricians of Russia. Clinical guidelines “Acute respiratory viral infection (ARVI)”, children, ID 25_3, published in the guidelines database on September 2, 2026 (in Russian). Accessed October 8, 2026.
  4. Russian Ministry of Health. Clinical guidelines “Acute respiratory viral infections (ARVI) in adults”, ID 724_2, published in the guidelines database on August 4, 2025 (in Russian). Accessed October 9, 2026.
  5. ICTV (International Committee on Taxonomy of Viruses). ICTV Virus Taxonomy Profile: Adenoviridae 2022. J Gen Virol 103(3). Accessed October 7, 2026.

This article was prepared by our editorial team from official sources and does not replace a doctor’s advice. Found an error? Write to us.