Here’s an expert opinion from the National Academy of Sciences on the prospective effects of various conditions of temperature and humidity on the “novel coronavirus”. From the conclusion:
Some limited data support a potential waning of cases in warmer and more humid seasons, yet none are without major limitations. Given that countries currently in “summer” climates, such as Australia and Iran, are experiencing rapid virus spread, a decrease in cases with increases in humidity and temperature elsewhere should not be assumed. Given the lack of immunity to SARS-CoV-2 across the world, if there is an effect of temperature and humidity on transmission, it may not be as apparent as with other respiratory viruses for which there is at least some pre-existing partial immunity. It is useful to note that pandemic influenza strains have not exhibited the typical seasonal pattern of endemic/epidemic strains. There have been 10 influenza pandemics in the last 250-plus years—two started in the northern hemisphere winter, three in the spring, two in the summer and three in the fall. All had a peak second wave approximately six months after emergence of the virus in the human population, regardless of when initial introduction occurred.
Additional studies as the SARS-CoV-2 pandemic unfolds could shed more light on the effects of climate on transmission.
In summary, though experimental studies show a relationship between higher temperatures and humidity levels, and reduced survival of SARS-CoV-2 in the laboratory, there are many other factors besides environmental temperature, humidity, and survival of the virus outside the host, that influence and determine transmission rates among humans in the “real world”.
Cheery, no?
Is this a fair summary?
- We shouldn’t bet the farm on the summer baking the virus out.
- It is likely, nearly certain, that SARS-CoV-2 will return in the late summer or early fall.
To that I would add that New York City may have provided a nearly optimal environment for the virus: it was the right temperature, the right humidity, and a lots of travel back and forth with China in the weeks of active spread there.
Said another way, I don’t think we should be too quick to attribute successes against SARS-CoV-2 to the actions that have been taken. We don’t know enough, it’s more complicated than that, and the situation is very fluid.
Are Iran and Australia currently in “summer†climates in the same way? Yesterday Tehran had a high of 46 degrees, low of 32. What was it when it was spreading? Australia didn’t have community spread until March (sister contracted from brother returning from trip from Iran; healthcare worker caring for the 30 or so non-community spread cases).
This I learned from Australian healthcare website: “While you can catch the flu at any time, it’s more likely to happen in the colder months of the year (April to October).” Weather sounds crazy on the other side of the world, but in different ways.
Yeah, I thought of commenting on that as well. It was summer (until a couple of weeks ago) in Australia but not in Iran. That heat or humidity are factors but not exposure to sunlight is an assumption not a demonstrated fact.
Everything in Australia sounds crazy. Maybe it’s from all of that standing upside down. 😉 I guess that’s why I like their television.
Looks like NYC Covid probably mostly from Europe.
https://www.foxnews.com/science/new-york-area-coronavirus-outbreak-originated-primarily-in-europe-not-china-report
Steve
I had read that elsewhere. Given the experience in Italy and Spain it does make you wonder if a different strain of the virus emerged in Europe, particularly in Southern Europe. Historically, the relationship between Italy and Iran has been strong and IIRC Italy has been a major Iranian trading partner. Relationship?
The more I read about this virus, the less I know. I’m not convinced we can expect what happened 100 years ago to recur.
But take comfort, no matter how many times it comes around, it can only kill you once.
@steve, there have been a couple of genomic papers out the last couple of days that are getting panned by genomicists. Can’t tell if this is one of them.
https://twitter.com/LucyvanDorp/status/1248368782248214529
(Not thinking its crazy that China to Iran to Italy to US. My city’s first case was traced from Switzerland through Florida.)
No, different papers.
Here in Georgia we’ve had a disproportionately high number of deaths, which when coupled with low rate of testing leads to the assumption that we have many more cases than the confirmed number. Weather has been unseasonably warm, generally high 70’s and even into low 80s some days. We did have a lot of rain until recently which makes me wonder if the controlling factor is UV light rather than temperature.
When I read about the NYC- Europe connection my thought was that the China travel ban probably helped a great deal on the west coast but the Europe travel ban came much later so lots of cases made their way to East cast, especially NYC.
But the idea of a more virulent strain also seems like a plausible hypothesis.