Hong Kong flu has returned to Russia: what are its symptoms, what is dangerous

The incidence of influenza is increasing in Russia. According to Rospotrebnadzor, the influenza A(H3N2) strain, also known as "Hong Kong", was detected in more than 80% of cases. At the moment, there are reports of at least six regions where the virus could have entered. Experts warn that the peak of the epidemic wave is expected soon after the end of the New Year holidays. For more information, see the Izvestia article.

What is the Hong Kong flu?

Hong Kong flu is a type of seasonal influenza A caused by a strain of the virus, which is designated as A(H3N2). Acute respiratory disease affects the mucous membranes of the nose, oropharynx, trachea and bronchi, leading to serious complications. The strain got its name after the first major outbreak that occurred in Hong Kong in 1968. Then, in just two weeks, about 500 thousand cases of the disease were registered.

The highly contagious virus quickly spread beyond Asia. By the end of 1968, he had reached Great Britain, the countries of Western and Eastern Europe, and also affected Australia, part of Africa, and the states of Central and South America. According to various estimates, the death rate reached from one to four million people during that period. Most deaths were recorded among infants and the elderly.

The pandemic wave reached the USSR, where the peak incidence occurred in 1969 and 1970. Despite the fact that the vaccine was developed fairly quickly, its mass production and use began after the main peak of morbidity in many countries. However, the A (H3N2) strain has not disappeared since then. The virus mutates quickly, which preserves the likelihood of re-infection.

The danger of H3N2 lies not only in its severe course, but also in the high risk of complications that can develop on the 4th-7th day of the disease. These include:

• viral and bacterial pneumonia;
• otitis media and sinusitis;
• myocarditis (inflammation of the heart muscle);
• inflammation of the bronchial mucosa (bronchitis);
• damage to the nervous system (meningoencephalitis);
• severe respiratory failure;
• exacerbation of chronic diseases.

The surge in morbidity in Russia

The last cases of Hong Kong flu infection in Russia were recorded in late October and early November 2023. Most people got sick while abroad. The highest number of cases was observed in the Tyumen, Amur, Oryol regions, Perm Krai and Sakhalin Oblast.

A new increase in the incidence has been recorded since November 2025. The difficult situation has developed mainly in the eastern and central regions of Russia — in the Far East, Siberia and the Urals. Information about confirmed cases is also coming from other regions.

For example, in the Tyumen region, the virus was detected in three people, including two children, and in the Orel region — in a student of a local college. The infection was reportedly brought to Sakhalin from abroad by one of the local residents.

Clinics are preparing to increase the flow of patients. According to Rospotrebnadzor, the epidemiological picture is complicated by the simultaneous circulation of COVID-19. According to the agency, about 9.7 thousand cases have been registered recently.

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How the A (H3N2) virus is transmitted

The transmission mechanism of Hong Kong flu is standard for many respiratory viruses. The main one is airborne: when coughing, sneezing and talking loudly with an infected person.

The virus can remain active on various surfaces, such as door handles and handrails in transport. Getting from them to the hands, and then to the mucous membranes of the mouth, nose or eyes, it easily penetrates the body.

The insidiousness of the Hong Kong strain lies in the fact that, as a rule, only 1-2 days pass from the moment of infection to the appearance of the first symptoms. A person remains contagious for another 5-7 days, which ensures the rapid spread of the disease in groups.

The main symptoms of the disease

The disease is characterized by an acute, often sudden onset. The main symptoms include:

• a sharp rise in body temperature to 39-40 °C,
• severe chills;
• a headache;
• sore throat;
• aching muscles and joints;
• a dry, debilitating cough.
• marked weakness and loss of strength.

This season, doctors also note acute "shooting" pain in the ears associated with edema of the eustachian tube, which can lead to complications in the form of otitis media. Redness of the whites of the eyes is also often observed.

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Who is at risk

The severe course of the Hong Kong flu and the development of complications most often occur in patients whose immunity is still being formed or whose immune system becomes more vulnerable with age.

The virus poses a serious threat to:

• children under 5 years of age;
• elderly people over 65 years of age;
• pregnant women.

The virus is also dangerous in the presence of chronic diseases of the lungs, cardiovascular system, diabetes mellitus, obesity, as well as for people with immunodeficiency conditions.

Preventive measures: how to protect yourself

In the context of the increasing incidence of Hong Kong flu, prevention is of key importance. The only reliable way to protect against severe forms of influenza and its complications is vaccination. Modern vaccines are developed taking into account the mutations of the virus, therefore they are quite effective. And although vaccination does not guarantee complete protection against infection, it significantly reduces the risk of severe disease.

Other measures:

• Hygiene: regular hand washing with soap, the use of antiseptics, wearing masks in crowded places.

• A balanced diet rich in vitamins and a healthy lifestyle, which helps strengthen the overall immune system.

• Ventilation and humidification of the air, regular wet cleaning of the premises.

• Responsible behavior: if symptoms of acute respiratory viral infections or flu appear, you should stay at home, call a doctor and limit contact with others.

Earlier, Izvestia was told whether there is a threat of a pandemic of avian flu in Russia.

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