Six states Maharashtra, Tamil Nadu, Gujarat, Delhi, Rajasthan and Madhya Pradesh account for over 80 per cent Covid-19 cases in India! Most cases in these states are from densely populated metropolitan cities where social distancing is difficult and hygiene a concern.
And now, India Today Data Intelligence Unit (DIU) has found that not only coronavirus, but these states are also hubs of swine flu infections. The findings were made after calculating the correlation of coronavirus cases and deaths with Acute Respiratory Infection (ARI), pneumonia and swine flu, all of which affect the respiratory system and have similar symptoms.
Symptoms of Covid-19 are similar to ARI fatigue, fever, chills, sore throat and difficulty in breathing. Covid-19 at a severe stage can advance into pneumonia. The swine flu pandemic, which shook the world in 2009, also impacted the human respiratory system. Also known as H1N1 virus, the swine flu outbreak occurred in India in 2015.
What does data say?
DIU calculated the correlation coefficients of cases/deaths of coronavirus with ARI, pneumonia and swine flu. The cross-sectional analysis showed that the correlation of coronavirus with ARI and pneumonia is weak (close to 0). This means states with high or low coronavirus cases/deaths do not exhibit high incidence of ARI and pneumonia.
However, things change for swine flu.
DIU calculated the correlation coefficient of cases/deaths of coronavirus as of May 25 with the five-year average swine flu cases/deaths in 33 states and Union Territories. For both cases and deaths, we found significant positive correlation of high degree.
Cases
The Pearson correlation coefficient “r” between coronavirus cases and five-year average swine flu cases was 0.73, which is high. The P-value was less than 0.05, which means the correlation coefficient was also statistically significant.
This in simple terms means that states with a high number of coronavirus cases had also recorded a high number of swine flu cases.
For instance, Maharashtra had a little over 50,000 Covid-19 cases as of May 25. On an average, it also records 3,937 H1N1 infections every year, which is the second highest in India after Gujarat (4,461) the state with the third highest number of coronavirus cases.
The vice-versa is also true. So far, the total cases in the seven north-eastern states have been low below 700, of which 92 per cent is from Assam and Tripura. These states also recorded low swine flu cases in the last five years an average of 68 per year.
Deaths
The correlation between Covid-19 and H1N1 deaths was even stronger than cases. The correlation coefficient between coronavirus and swine flu deaths was 0.92, which is very high. Here too, the P-value was less than 0.05, which means the coefficient was significant.
Just like cases, states, where the coronavirus death toll was high, had also recorded a high swine flu death toll in the last five years. Maharashtra has the highest number of coronavirus deaths in the country at 1,635. It also had the highest number of swine flu deaths in the last five years an average of 483 per year, which is the highest in the country.
Maharashtra is followed by Gujarat, both in coronavirus and swine flu deaths. Around 830 people had died of Covid-19 in Gujarat as of May 25. The state also reported 250 swine flu deaths every year on an average. Some bigger states such as Kerala, Bihar, Jharkhand and Odisha have witnessed low death counts for both coronavirus and H1N1 influenza.
Expert opinion
Bhramar Mukherjee, professor of epidemiology at University of Michigan, USA, believes this correlation could be partly due to high population density. “Some of it is explained by total population, percentage of urban population and population density. Maharashtra and Gujarat have high total and urban population. We know ‘R’ in rural and urban areas is drastically different,” she says.
‘R’ is the reproductive rate of the virus, which tells us how many persons can be infected by one confirmed case.
Giridhar R Babu, professor and head of lifecourse epidemiology at Public Health Foundation of India, says, “The correlation between H1N1 and Covid-19 seems to be associated with the general susceptibilities of the population to flu-like illness in these areas. However, correlation is not causation and therefore we need to explore further in terms of what the commonalities are across these regions.”
Professor Bhramar Mukherjee, however, pointed out that both Covid-19 and H1N1 have different targets. “There are two major differences between Covid-19 and H1N1. One, mortality rates appear to be much higher for Covid-19 and it appears to be more infectious. Two, H1N1 deaths are common among people below 65 years of age, while Covid-19 deaths are higher among the elderly (65 and above),” she said.
More facts
The case fatality ratio of Covid-19 in India was 2.89 per cent as of May 25, while the average swine flu fatality rate in the last five years has been 6.17 per cent. This means swine flu has been deadlier than Covid-19, but that’s because of percentages at play.
It took swine flu five years to infect 1,26,958 people in India, while almost 1.4 lakh people have been infected by coronavirus in just four months. In the last five years, swine flu killed more than 7,800 people, while coronavirus has killed over 4,000 people in four months.
Further, the transmission rate of coronavirus at the current stage, according to a preprint study by a group of doctors is in the range of 2-2.5, while the same for the 2009 H1N1 pandemic was 1.4-1.6, which explains why coronavirus is so contagious.
Moreover, a vaccine for swine flu is now available, which is not the case with coronavirus.
