H3N2 Virus: Symptoms, Causes, and Prevention

It may start subtly as a fever, persistent cough or extreme exhaustion that won’t go away. What at first seems like another bout of the flu, which happens to come around every year, is increasingly recognised as the H3N2 influenza virus. There has been a rise in influenza cases among people residing in many cities in India recently, with people wanting to know whether this is the H3N2 flu.

According to the World Health Organisation (WHO), H3N2 or Influenza A virus, causes more severe symptoms among older adults and children as compared to the H1N1 virus. 

The distinguishing factor in this particular season, however, is not just the increase in numbers but also how the disease affects certain individuals and how rapidly symptoms develop in such people. This is why knowing about H3N2, its transmission, and prevention strategies is important.

As always before, the aim is not to cause alarm but to take precautions. In the following blog, we will look into the symptoms, causes and preventive measures for the H3N2 virus.

What Is the H3N2 Virus?

H3N2 virus is one of the subtypes of the influenza A virus. It is one of the primary agents that cause influenza. Depending on the type of virus and the proteins present in the virus, the virus is named accordingly. The H3N2 virus got its name from two types of proteins present in the surface layer of the virus, namely, hemagglutinin and neuraminidase.

The strain was first discovered in humans in the late 1960s and has spread in every flu season. Since the virus mutates continuously, H3N2 has become one of the most dominant strains in current flu seasons, frequently evolving new variants which partially break the immune mechanism built up from previous vaccinations or infections.

Unlike the common cold virus, H3N2 causes more severe illness developing faster. It also affects animals as well as humans, which gives the virus more opportunities to mutate through genetic reassortment, a vital reason for which annual flu vaccine matters.

H3N2 vs Common Cold vs COVID-19

It is important to understand that H3N2, COVID and the common cold can present with different degrees of severity, and not all individuals suffer from similar symptoms. Therefore, it is important to understand the most common and vital symptoms.

Features	H3N2	COVID-19	Common Cold
Beginning	Within 1-4 days of exposure.	Gradually begins	Gradually starts, within 2-3 days.
Fever	100℉ or above.	Can range from mild to severe	Mild or very rare.
Cough	Dry cough; can stay for weeks.	Common	Mild or often present with mucus.
Fatigue and body aches	Moderate to severe.	Can be extreme	Mild
Other symptoms	Sore throat, diarrhoea, and vomiting in a few cases.	Shortness of breath, loss of smell, loss of taste, sore throat.	Runny or blocked nose with sneezing.

How Does H3N2 Spread?

It is not just a simple virus. There are a few conditions that trigger the spread of the virus.

• Close contact in crowded places such as public transport.
• Lower immunity among the population.
• Changes in humidity and temperature levels result in the thriving of respiratory viruses.
• The virus can be transmitted through contaminated surfaces.
• The constant mutation of the virus helps it to break the immune defences.

Certain environmental factors cause the virus to thrive even more: a dense population of individuals in urban areas, cold or fast-changing weather (this increases the survival period of the virus outside the host), low immunisation rates, bad cough and sneeze etiquette, and crowded environments such as schools, daycare centres, and hospitals. The infected individual is capable of spreading the virus one day before the onset of his symptoms.

Several reasons contribute to increasing incidences of H3N2:

• High population density, particularly in urban areas, due to the proximity of the infected individual and all the other people surrounding him/her.
• Very cold weather and sudden changes in weather, because it makes it possible for the virus to survive longer in the environment.
• The rate of immunisation being very low, which means many people have no immunity against the disease.
• The incorrect manners used when coughing and sneezing, which is not covering the nose and mouth.
• Close-contact places like schools, kindergartens, and hospitals where the virus is easily transferred from one person to another.

Infected individuals have the potential to transmit the virus about a day prior to experiencing the first symptoms themselves.

H3N2 vs Swine Flu

The following table shows the comparison between these two types of virus.

Features	H3N2	Swine Flu
Beginning	Within 1-4 days of exposure.	Patients often become unwell within a few hours.
Fever	100℉ or above.	High-grade fever, often for a long period.
Cough	Dry cough, can stay for weeks.	Persistent cough lasting up to 3 weeks.
Fatigue and Body ache	Moderate to severe.	Severe body ache with weakness.
Other symptoms	Sore throat, diarrhoea, and vomiting in a few cases.	Sore throat, shortness of breath and wheezing.

What are the Main Symptoms of the H3N2 Virus 

Having knowledge about the timeline of symptoms of the H3N2 virus helps you to identify the condition promptly.

Usually, after being exposed to the H3N2 virus, symptoms will appear in 1 to 4 days’ time. The sudden development of symptoms is one of the things that distinguish flu from just having a regular cold.

Common Symptoms

Some of the common signs of the H3N2 virus are:

• High fever, generally above 100.4°F (38°C) degrees, possibly accompanied by shivering.
• Dry and ongoing cough.
• Sore throat that could be severe enough to affect the ability to swallow.
• Aching body and joints.
• Exhaustion and lack of energy.
• Headache.
• Nasal congestion and colds.
• Sometimes, there may be symptoms of nausea, vomiting or diarrhoea.

It can be anticipated that the fever and body aches will disappear within three days, and the coughing and tiredness will continue for one to two weeks.

Red Flag Symptoms- When to Act Promptly

If you or your loved one feel the following symptoms, then seek medical attention without any delay.

• Trouble breathing or experiencing chest pain
• Blue colouration of lips, face, or fingernails
• Fever that cannot be reduced by any form of medication
• Symptoms of dehydration, including very low urine production
• Disorientation or excessive drowsiness

Such symptoms may indicate complications like pneumonia, bronchitis, or ear or sinus infection.

H3N2 Virus Symptoms in Children

The symptoms of H3N2 virus among children will differ somewhat from those experienced by adults. In addition to fever, cough, and body aches, in children the virus may manifest itself as:

• Vomiting and diarrhoea
• Poor appetite and low fluid consumption
• Unusual irritability or increased drowsiness
• Breathing difficulty in severe cases

Children are highly susceptible to both acquiring and transmitting H3N2 influenza due to the frequency with which children touch their face and the amount of time spent with other children in schools and childcare facilities. 

How Is H3N2 Diagnosed and Treated?

If symptoms are severe, unclear, or affect someone in a high-risk group, a doctor may recommend testing to confirm influenza A and distinguish it from other respiratory illnesses.

How Doctors Confirm H3N2

The diagnosis of H3N2 virus includes clinical diagnosis as well as laboratory tests. Several special tests are performed to confirm the infection and differentiate it from other respiratory diseases. The tests are:

• Rapid Influenza Diagnostic Test

This test is performed for initial screening using a nose and throat swab, and it offers rapid results within a few minutes. This RIDT test is convenient for rapid results.

• Viral Culture

It allows further testing and characterisation of particular strains, which can be helpful to control the virus and monitor the evolution of the virus.

• PCR Testing

It is a molecular process that detects viral genetic material with sensitivity and specificity. This test is useful for confirming the infection when quick and accurate reports are needed.

• Serological Tests

Serological tests diagnose the presence of antibodies formed by the immune system in response to H3N2 virus infection. These tests may be performed for epidemiological investigations, research and surveillance.

How H3N2 Is Treated

For most healthy adults, treatment is supportive rather than curative:

• Ample rest to allow the body to overcome the infection
• Adequate fluid intake to avoid dehydration
• Fever reducers such as paracetamol and ibuprofen, as directed
• Salt water gargles and steam inhalations to help with the sore throat and congestion symptoms

Antiviral medications, such as oseltamivir, zanamivir, peramivir, or baloxavir, may be prescribed for high-risk individuals or those who are critically ill. They are most effective when started within two days of symptom onset and usually last for five days. However, antibiotics cannot cure H3N2 because it is a viral infection; antibiotics are used only if there is a secondary infection such as pneumonia.

How Can You Prevent H3N2 Infection?

The first and foremost measure is getting an annual flu shot, because the virus changes each year enough that the shot composition must change. Other than that, there are things people should do daily:

• Do not have any physical contact with those who show symptoms.
• Cover your nose and mouth when you cough or sneeze.
• Wash your hands frequently.
• Do not touch your face.
• Ensure that other good health habits such as good sanitation, exercise, sleep, and healthy dieting are maintained.

Who Should Prioritise Vaccination

Vaccines meant for seasonal flu can help prevent the flu all through the year. The CDC provides recommendations regarding individuals at risk of having severe influenza cases, including:

• Persons aged 65 years and older
• Pregnant women
• People with weakened immune systems or underlying health conditions
• Children younger than five years.

Because the influenza virus has the ability to mutate, while also having the ability to swap genetic information with another strain. 

Conclusion

H3N2 Influenza virus is a quick-acting influenza A virus which exhibits the symptoms of common influenza, such as fever, body pains, and coughing, and takes around a week to heal, provided that the infected person gets proper rest. The high risk of contracting severe complications due to the H3N2 virus includes children, the elderly, and people who have certain diseases, and they must keep a lookout for any symptoms. The best method of protection from getting H3N2 is yearly vaccination.

If you or your loved ones are suffering from any of the above-mentioned symptoms, then visit the best general physician in Gurgaon without any delay.

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