Can summer slow down the coronavirus outbreak in India? New studies shed light
A new study found that in extreme cold and very hot and wet conditions the novel coronavirus is “largely absent.” But does it mean India should just wait for summer to come in full bloom? NO! Read why.
Can the onset of summer halt the spread of coronavirus and Covid-19 in India? This question has been repeatedly asked since the earliest reports of Covid-19 in this country. But will it? A new study shows that temperature and humidity do make a difference in the ability of the virus to infect large numbers.
Since the beginning of the outbreak, there have been differing opinions on this subject, as most of it is still speculation. After all, this particular strain of coronavirus didn’t exist until around November last year.
As soon as the earliest reports of covid-19 started arriving, several people were of the opinion that India has an "innate, natural defence against coronavirus".
Several experts including K K Aggarwal, president, Heart Care Foundation of India, said that India is largely safe because "after ravaging the countries that have more agreeable climatic conditions, viruses — no matter however deadly — lose their killer edge once they encounter India's relatively high temperature and humidity that make life difficult for them."
US President Donald Trump's televised claim that April sunshine could chase away the scourge, also helped the theory gain some steam. After all, influenza outbreaks in the past have wilted with seasonal changes.
A doctor in Maharashtra took it too far claiming that the fear over novel coronavirus is unwarranted because it's a "Chinese fad" which will not survive the Indian summer. He was duly served a notice by the Maharashtra Medical Council for prima facie violation government advisories and was asked to substantiate his claim.
This theory, propounded by several others, was almost shut down by the Union Health Ministry on March 12 with a short and clear response: even though flus are not usually common in summer, there is no evidence or study to suggest that high temperature kills coronavirus. Even officials of the World Health Organization had called it a myth saying there’s no reason to believe temperature will play a role in the outbreak but that the subject was worth investigating.
What the studies say
He states that there has been suggestive evidence that temperature and humidity do make a difference in the spread of the coronavirus - like Iran, which accounts for about 90% of coronavirus cases in the Middle East, is unique in the region for mostly sitting on a plateau where winter conditions resemble most European countries.
At the same time, some Southeast Asian nations with close business and tourism links to China have seen surprisingly few cases, even if you assume their less developed public health systems are not testing enough. Thailand, Indonesia, and the Philippines have each seen fewer cases than Estonia, Slovenia or Iceland, despite a combined population more than 100 times as large.
Then he talks about the study which plots recorded cases against climate conditions to suggest that there is indeed a significant correlation between outbreaks and the weather.
Acting on the generalisation that all organisms have a degree of environmental specialization, that is apart from the host and the virus itself, an ideal environment also plays a huge role in the virus' spread.
The researchers from Spain, Portugal, and Finland stated that the virus is "largely absent" in very hot and humid conditions, and in extreme cold conditions like in polar climates.
"Much of the tropics have low levels of climate suitability for spread of SARS-CoV-2 Coronavirus owing to their high temperatures and precipitation (used here as a surrogate for humidity), followed by polar climates, where conditions of extreme cold temperatures seem to be beyond the virus critical minimum tolerance values."
This means that people in tropical and polar climates are unlikely to see local transmission of cases, which can work in favour of India once the summer sets in. Though it has started getting warmer in some parts of India, much of north and north-east India are still warming up to a late summer.
The study also finds that arid regions will see a higher rate of infections but the worst-hit areas will be temperate countries and high-altitude areas closer to the equator.
Another study Fickling cites comes to a similar conclusion after analyzing the infection rates in 100 Chinese cities. "That rate, known as the R0, is a key determinant of an infection’s propensity to spread. For Covid-19 it’s currently estimated to be around 2.2, but moving it below 1 should, if sustained, be enough to turn the current out-of-control epidemic into an outbreak that goes extinct on its own," he states.
A study by four Beijing-based researchers found that increasing the temperature by one degree centigrade reduces the R0 by 0.0383 and increasing humidity by 1% pushes it down by 0.0224.
Can we relax then? No.
Having talked about these studies, it's far from certain that a hot and humid Indian summer could halt the coronavirus' march. The findings of these studies confirm our traditional knowledge that flu outbreaks ease in summer. So we must be careful to see that we don't favour our confirmation bias ahead of scientific and real facts.
Let's say even if the spread of SARS-CoV-2 or the novel coronavirus slows down in the summer, some evidence suggests it migrates to the opposite hemisphere, before returning again with cooler weather. So, even if the coronavirus does subside in the summer, it could return in the fall.
Also, as Fickling suggests, "Both studies are still just computer models, and neither has been through peer review. On top of that, even a reduced rate of infection will only slow, rather than halt the spread of this pandemic. In most places, it won’t even be sufficient to push the R0 below 1, in the absence of other measures such as social distancing."
Things look so grim right now, with a possibility of a grimmer few months, that maybe "we should take whatever comfort we can get".