Table of contents:
- Online Symptom Test
- Result:
- Difference between COVID-19 and H3N2
- How to confirm the diagnosis
- What to do in case of suspicion

H3N2 infection symptoms usually appear between 3 and 5 days after contact with the virus, which corresponds to the incubation period of the virus, and the person can still transmit the virus during this period or after the onset of symptoms.
H3N2 symptoms are usually more intense in the first 48 hours, the main ones being:
- High fever in the first days, above 38ºC;
- Sore throat;
- Cough;
- Headache;
- Body pain, especially in the joints;
- Sneezing, runny nose and stuffy nose, in some cases;
- Chills;
- Loss of appetite;
- Nausea and vomiting;
- General malaise;
- Eye irritation;
- Diarrhea, especially in children.
In the case of suspected H3N2, it is important to stay in isolation, rest and drink plenty of fluids during the day to prevent transmission of the virus to other people and favor recovery. In addition, to relieve symptoms, the use of anti-inflammatory or analgesic drugs may also be indicated. Learn more about the H3N2 flu and its treatment.

Online Symptom Test
To know the risk of having the flu caused by the H3N2 virus, select the symptoms shown in the test below:
- 1. Fever above 38º C Yes No
- 2. Sore throat Yes No
- 3. Frequent coughing Yes No
- 4. Headache Yes No
- 5. Sneezing, runny nose and/or stuffy nose Yes No
- 6. Body pain Yes No
- 7. Loss of appetite Yes No
- 8. Fatigue and general malaise Yes No
Result:
Make an appointment with a specialist

Difference between COVID-19 and H3N2
COVID-19 and H3N2 influenza are respiratory infections, however they are caused by different infectious agents: COVID-19 is caused by the SARS-CoV-2 virus, while the H3N2 influenza is caused by the virus H3N2, which is a subtype of the Influenza A virus.
Because they are respiratory diseases, the symptoms can often be confused. However, the symptoms of COVID-19 become more intense as time goes on and can be persistent depending on the person's immune system, whereas in the case of H3N2 the symptoms are more intense in the first 48 hours, improving over the course of the day. time, even if no treatment is performed and usually last up to 10 days.
In COVID-19, it is still possible that there is loss of smell and taste, shortness of breath, excessive tiredness and difficulty breathing, which is not observed in the case of H3N2, whose symptoms are milder and include pain and inflammation throat, cough and stuffy nose, for example. See more about the difference between COVID-19, the flu and a cold.
How to confirm the diagnosis
Confirmation of the diagnosis is mainly done through the evaluation of symptoms, however, in some cases, specific tests may be requested by the doctor to differentiate H3N2 infection from SARS-CoV-2 infection, which is the virus responsible for COVID-19.
The test to confirm the diagnosis of H3N2 is done from a sample of the nasopharynx, which is collected through a swab. From this sample, it is possible to perform an exam to identify specific antibodies against the H3N2 virus, antigens or differentiate between H3N2 and H1N1. In addition, it is possible to perform a test to differentiate the H3N2 virus from the SARS-CoV-2 virus, through the real-time PCR test.
According to the signs and symptoms presented by the person, the doctor may also recommend performing an exam capable of identifying different respiratory viruses, being useful in the differential diagnosis of infection by Influenza A and B, respiratory syncytial virus, coronavirus, adenovirus, rhinovirus, enterovirus, among others.
What to do in case of suspicion
In case of suspected H3N2 infection, it is important to follow the recommendations of the State or Municipal He alth Department, as this way it is possible to prevent he alth units from becoming too full, which could increase the risk of virus transmission. Thus, in some cases, it may be indicated that a teleconsultation is carried out so that the signs and symptoms presented by the person can be evaluated and the need to perform a test to confirm infection by H3N2 can be verified.
Also, in the case of suspected H3N2 infection, it is important to stay in isolation for about 7 to 10 days to prevent transmission of the virus to other people. You should also rest, drink plenty of fluids during the day and have a light and easily digestible diet. It may also be recommended to use analgesic or anti-inflammatory drugs to relieve symptoms.
To prevent H3N2 infection and its transmission, it is also recommended that face masks be used, that hands be disinfected and washed regularly and that environments with many people and with little air circulation are avoided., it is important to maintain social distance and avoid sharing personal items.
Influenza vaccination is also a way to prevent the occurrence of H3N2, especially severe cases, which can happen more easily in the elderly, children and people with comorbidity. See more about H3N2 vaccination.