Most parts of India are in the grip of swine flu with western and southern states of the country the worst hit. Tamil Nadu and Karnataka account for more than 55% of all cases, while Maharashtra has recorded half of all deaths.
India had 8,648 cases and 345 swine flu deaths till May 7 this year, compared to 1,786 cases and 265 deaths in 2016, reveals data from the ministry of health and family welfare.
Tamil Nadu alone recorded 2,798 cases till May 7, which is more than the total tally of 2016.
Maharashtra has the highest death toll, with 181 people succumbing to H1N1 complications till May 7.
With just 130 infections, Gujarat has an unexplainably high death toll of 31, which puts the state’s death rate – the percentage of people dying of the infection – at close to 23.8%, compared to the national average of 3.98%.
India witnessed worst outbreak of the Swine flu, renamed the influenza A(H1N1)pdm09 virus by the World Health Organistion (WHO), in the pandemic years of 2009-10 when the disease affected close to 50,000 people and killed more than 2,700 across the country.
“Flu outbreaks appear to hit western India harder, show India’s earliest records when Odisha, West Bengal and the north-east India escaped the worst of the 1918 Spanish Flu outbreak, which killed 40 million people worldwide,” said an epidemiologist at the Union health ministry and family welfare.
“We definitely need studies to understand why the virus behaves differently in different parts of the country.”
“Viruses are not predictable at all. This year, the hotspots in Maharashtra are in Aurangabad, Nashik and Pune, but Mumbai is not affected,” he said.
“We don’t have an answer to this. We definitely need studies to understand why the virus behaves differently in different parts of the country,” says Dr Soumya Swaminathan, director general of the Indian Council of Medical Research.
Each year, annual influenza outbreaks affect 5-15% of the world’s population, estimates the World Health Organisation, causing symptoms of fever, lethargy and cough.
Most people recover within a week, with deaths occurring from complications such as pneumonia and multi-organ failure in people at risk, such as children with respiratory problems, pregnant women, older adults and those with chronic ailments such a lung diseases, heart disease and diabetes.
People are infectious from the day before they develop symptoms until up to a week after.
Influenza A (H1N1)pdm09 virus has been the predominant seasonal flu strain worldwide over the past seven years. But in 2017, the influenza A(H3N2) and B viruses became the predominant strains, said the WHO.
In India and the Maldives, influenza A(H1N1)pdm09 continues to be the predominant strain, with neighbouring Pakistan reporting sporadic cases of influenza A(H3N2) viruses in the recent weeks.
Flu peaks twice a year in India, in July and August and again from October to February. But cases are reported throughout the year.
Getting vaccination each year reduces symptoms, shortens the duration of the illness and lowers doctors’ visits and flu-related hospitalizations.
But people in India rarely get vaccinated against H1N1.
Each year, the WHO recommends a vaccine that targets the three most deadly flu strains based on flu-tracking data from 143 National Influenza Centres in 113 countries, including India. In the 2017 vaccine, the A/California/7/2009 (H1N1)pdm09 virus has been replaced with an A/Michigan/45/2015 (H1N1)pdm09 virus, while the other two viruses -- the A/Hong Kong/4801/2014 (H3N2) virus; and B/Brisbane/60/2008 – remain the same as last year.
The quadrivalent vaccine against four flu viruses includes the B/Phuket/3073/2013 virus.
Vaccinating people at risk is a must in regions where infection continues throughout the year and chances of death from complications are higher because of late diagnosis, undernourishment and poor health infrastructure.
In older persons, vaccination lowers influenza-related illnesses by 60% and deaths by 70-80%.
Among healthy adults, it reduces illness by 70-90%, and in children, cuts flu-related ICU admission by 74%.
Treatment in hand
“Now is a good time for people in India to get vaccinated against seasonal flu because it takes four to six weeks for the protective effects to kick in. Getting vaccinated now will protect people when the flu peaks during the monsoons and again in winter,” said Dr Krishan Chugh, director and head of pediatrics at Fortis Memorial Research Institute, Gurugram.
“As more people get vaccinated, the viral load in the community goes down.”
“Vaccination not just protects you from infection but also makes you less contagious and reduces the transmission of infection. As more people get vaccinated, the viral load in the community goes down and everyone develop ‘herd immunity’, which makes fewer people vulnerable to serious flu complications,” said Dr Chugh.
All inactivated influenza vaccines contain trace levels of egg protein and should not be given to people with egg protein allergies.
The antigenic shift from A/California/7/2009 (H1N1)pdm09 to A/Michigan/45/2015 (H1N1)pdm09 in 2017 is a minor change and has not led to drug resistance against standard anti-viral medicines used to treat the H1N1 or influenced viral entry into cells, transmission and tissue tropism (cells and tissues that host the virus in the body).
“The Michigan strain has been milder than the California strain in the US and with fewer deaths this year, the trend in India seems to be the same,” said a health ministry official who did not want to be named.
Oseltamivir and zanamivir, the antiviral drugs used to treat H1N1, lower the viral-load, shorten the duration and severity of illness and make the patients less contagious.
“Both medicines are manufactured in India and all states have procured drugs. The government does not stockpile the flu vaccine because its life is nine months to a year, but since it is also manufactured in India, there’s no shortfall,” said the ministry official.