As of August, India has reported 14,447 influenza cases and 239 deaths, with Kerala recording the highest—2,929 cases and 52 deaths. NCDC confirms flu strains match those spreading globally
Published Nov 08, 2024 | 7:00 AM ⚊ Updated Nov 08, 2024 | 7:00 AM
flu vaccine
The National Centre for Disease Control (NCDC) has advised health professionals to administer the Southern Hemisphere 2024 quadrivalent vaccine—SH24 flu jab—to protect against four different influenza strains, as winter approaches and the disease continues to claim lives.
India has reported 14,447 influenza cases and 239 deaths as of August, with Kerala recording the highest numbers: 2,929 cases and 52 deaths.
According to NCDC, in India, influenza surveillance is conducted through a structured network of DHR-ICMR VRDLs and the National Influenza Centre (WHO-NIC) at ICMR-NIV Pune, which is also a WHO Collaborating Centre for GISRS, since July 2021. Under this surveillance, a network of 30 sites collects data and monitors influenza activity throughout the year.
The recommended vaccines include:
According to the National Centre for Disease Control (NCDC), recent testing of flu viruses in India shows they match the types spreading worldwide. These flu strains align with those included in the Southern Hemisphere 2024 flu vaccine recommended by the World Health Organisation (WHO), indicating that the vaccine should effectively protect people from the most common flu strains expected this season.
Additionally, testing has shown that these flu viruses remain fully responsive to antiviral drugs known as neuraminidase inhibitors, meaning current medications in this category continue to be effective for treating flu infections.
“The surveillance data for antiviral resistance among the tested influenza viruses indicates complete sensitivity to neuraminidase inhibitors, suggesting that the current neuraminidase inhibitors remain effective for the treatment of influenza infections,” said the NCDC.
“Neuraminidase inhibitors are a type of antiviral medication used to treat influenza. They work by blocking the function of neuraminidase, an enzyme on the surface of flu viruses. Neuraminidase allows newly created flu viruses to leave an infected cell and spread to others in the body,” said Hyderabad based physician Dr Sai Kiran Chilukuri.
By inhibiting this enzyme, neuraminidase inhibitors prevent the virus from spreading further, which helps to contain the infection. This limitation reduces the severity and duration of flu symptoms.
“In light of this, it is advisable to use the Southern Hemisphere 2024 quadrivalent vaccine in the upcoming influenza season. However, if the SH 2024 recommended component influenza vaccine is not available, it is recommended to procure the latest available quadrivalent influenza vaccine,” the NCDC stated.
Seasonal flu, also known as influenza or H1N1, is a contagious viral infection that primarily affects the respiratory system, including the nose, throat, and sometimes the lungs. This illness typically spreads during certain times of the year, particularly in the fall and winter, which is why it is called “seasonal.” The flu can cause serious complications, such as pneumonia, and may require hospitalisation.
In India, influenza is a significant public health concern, and vaccines are given to help protect against it. Since flu viruses change quickly, new vaccines are developed twice a year.
“Getting vaccinated reduces the risk of getting the flu and can lessen the severity of the illness. It also helps prevent the spread of the virus, especially to vulnerable groups like the elderly,” said Dr Chilukuri.
There are two main types of flu viruses that commonly affect people: Type A and Type B. Symptoms of the flu include fever, chills, cough, sore throat, runny or stuffy nose, body aches, fatigue, and sometimes vomiting or diarrhoea.
“The virus spreads through droplets when an infected person coughs, sneezes, or talks, and can also spread by touching contaminated surfaces and then touching your face,” said Dr Dr Chilukuri
The WHO recommends annual flu vaccinations, with the vaccine being administered in February for people in the Northern Hemisphere and in September for those in the Southern Hemisphere. India falls within the Southern Hemisphere tropical Asia vaccination zone, which influences the choice of flu vaccine strains tailored for the region’s seasonal patterns.
“While most people recover from the flu within one to two weeks, it can lead to serious complications in certain groups, such as young children, the elderly, and those with pre-existing health conditions like asthma, diabetes, or heart disease. Although the Indian Academy of Pediatrics (IAP) has not recommended universal vaccination due to limited data on flu-related illness and death in India, they do advise vaccinating high-risk children as soon as the vaccine becomes available, typically before the rainy season begins,” said Dr Chilukuri.
The WHO suggests that flu vaccinations in India should begin in April and continue until September, aligning with the monsoon and winter months when flu activity peaks.
Flu vaccine costs range from ₹2000 to ₹2500, depending on factors like brand and hospital service provider. While influenza vaccines are not widely available in government hospitals, they can be found in private hospitals and clinics. Government employees may have access to the vaccine through the Central Government Health Scheme (CGHS).
In September, the World Health Organisation (WHO) announced its recommendations for the composition of influenza vaccines for the 2025 flu season in the Southern Hemisphere.
These guidelines followed a four-day meeting focused on the influenza virus composition, held twice annually for each hemisphere. During these consultations, WHO convenes experts from its Collaborating Centres and Essential Regulatory Laboratories to review influenza virus data provided by the Global Influenza Surveillance and Response System (GISRS).
The recommended virus strains serve as a critical reference for national vaccine regulators and pharmaceutical companies to develop and licence vaccines for the upcoming flu season. Regular updates are necessary because influenza viruses constantly evolve, and vaccines must be adjusted to ensure optimal protection.
For the 2025 Southern Hemisphere flu season, WHO’s recommendation for trivalent vaccines includes the following strains:
A/Victoria/4897/2022 (H1N1)-like virus
A/Croatia/10136RV/2023 (H3N2)-like virus
B/Austria/1359417/2021-like virus
A/Wisconsin/67/2022 (H1N1)-like virus
A/District of Columbia/27/2023 (H3N2)-like virus
B/Austria/1359417/2021-like virus
For quadrivalent vaccines, the B/Yamagata lineage component remains unchanged, with the inclusion of a B/Phuket/3073/2013-like virus.
The names of influenza vaccine strains, such as A/Victoria/4897/2022 (H1N1)pdm09-like virus, follow a specific format, each part providing essential details about the virus. Here’s a breakdown of the key components:
Trivalent Vaccine Strains:
Quadrivalent Vaccine Addition:
This classification system provides clear, detailed information about each strain, ensuring vaccines are correctly formulated to protect against the most prevalent viruses for each flu season.
(Edited by Ananya Rao)
