Why in news?

Recent reports of a rise in the seasonal influenza cases in the Delhi-NCR area signifies the importance of seasonal flu vaccination, especially for high-risk groups like the elderly.

What is seasonal flu?

It is an acute respiratory infection caused by influenza viruses.
Spread – According to the World Health Organization (WHO), there are around a billion cases of seasonal influenza annually, including 3–5 million cases of severe illness.

Seasonal flu causes 2,90,000 to 6,50,000 respiratory deaths annually. 99 % of deaths in children under 5 years of age with influenza-related lower respiratory tract infections are in developing countries.

Transmission – It is contagious and can be passed on from one person to another when they cough or sneeze.
Onset of symptoms – It begin 1–4 days after infection and usually last around a week.
Symptoms – They are high fever, cough, sore throat, body aches and fatigue.
Severity – It causes mild to serious illness and in a few cases, mostly coinciding with a delay in hospitalisation, can even lead to death.
Treatment – Most people recover without treatment.
Medicines such as paracetamol, antihistamines and cough Syrups can help and in severe cases, antiviral medications are recommended.
Prevention – Vaccination is the best way to prevent the disease.
- Injectable form – Inactivated influenza vaccines and recombinant influenza vaccines.
- Nasal Spray – Live attenuated influenza vaccines.

Similarities between Seasonal Flu and Common Cold

Similar symptoms like sudden cough and sore throat, with high fever, accompanied by muscle pain, body aches, headaches, fatigue and stuffy nose.

Dissimilarities between Seasonal Flu and Common Cold

Both are caused by different viruses.
Both can have varying symptoms and severity.

What are the different types of influenza viruses?

There are 4 types of influenza viruses
- Influenza A, B, C and D.
Influenza A and B viruses circulate and cause seasonal epidemics of disease.

Types of Influenza Viruses
Influenza A Viruses	They are classified into subtypes as per the combinations of the proteins on the surface of virus. Currently circulating in humans are Subtype A(H1N1) Subtype A(H3N2) Only influenza type A viruses are known to have caused pandemics.
Influenza B viruses	They are not classified into subtypes but can be broken down into lineages. They belong to either B/Yamagata or B/Victoria lineage.
Influenza C virus	It is detected less frequently. It usually causes mild infections, thus does not present public health importance.
Influenza D viruses	It primarily affect cattle and are not known to infect people.

There are 2 peaks of seasonal influenza in India, one from January to March and the other in in latter part of the southwest monsoon, in August-October. Predominant strains in this season are Influenza A and Influenza B.

What are the control measures taken?

Surveillance – India has developed a near real time surveillance of cases of Influenza like Illness (ILI) and Severe Acute Respiratory Infections (SARI) presenting themselves in health facilities.
It is also through the country-wide network of diagnostic laboratories.
- Integrated Disease Surveillance Programme (IDSP)
- Virus Research & Diagnostic Laboratories (VRDLs)
Public awareness campaigns – Information, Education, and Communication (IEC) materials are used to inform the public about symptoms, preventative actions, and when to seek medical assistance.
Efficient healthcare guidelines – Extensive guidelines covering ventilatory care, treatment procedures, and patient classification have been released to reduce complications and mortality.
Supplying antivirals – The public health system provides free access to oseltamivir (Tamiflu), which is advised by the WHO.
Its sale has been allowed under Schedule H1 of the Drug and Cosmetic Act from February 2017.
Protecting healthcare professionals – Steps are being taken to provide safety kits like N-95 face masks and personal protective equipment (PPE) kits.

What are the challenges in control measures?

Continuous evolution of Influenza viruses – High population density, poor hygiene practices, indiscriminate antimicrobial use and conducive weather lead to the survival and spread of the virus.
Low vaccination rates – Influenza vaccine is not included into the government’s Universal Immunisation Programme.
Low adult vaccination rates – It is often overlooked due to a lack of information, misconceptions, and financial hurdles.
No national policy requires flu vaccine for high-risk persons, leaving it up to state discretion.
Disparity in healthcare access – Rural & marginalized communities have limited access to immunizations and treatments.
Surveillance gaps in private healthcare - While public facilities disclose incidents, private healthcare data is frequently underreported, limiting real-time monitoring.
Climate change – Seasonal epidemics of influenza may shift spatially and temporally.

What lies ahead?

Improve preparedness – Anticipating an outbreak and inculcating a sense of preservation, particularly among the high-risk groups.
Prioritise vulnerable groups – More attention to children, senior citizens and people with chronic respiratory conditions.
Targeted awareness campaigns – It must be clear, urgent in tone, and make an impact on the high-risk groups particularly, because, very simply, vaccines save lives.
Formulating a national flu vaccination strategy – Steps can be taken to make annual flu vaccines mandatory for high-risk populations and incorporating influenza vaccines into government health programs and subsidize expenses.
Strengthening surveillance – Encouraging private hospitals to provide real-time data to flu surveillance networks.

Seasonal Flu