Finally getting around to Jane Campion’s Bright Star and watching John Keats slowly die after catching a chill, and I wondered where the science is on this nowadays. I know it’s been proven that cold is an unlikely direct cause of human illness. But what about indirect? Can a chill affect the immune system to make succumbing to a viral infection more likely? Or is that too purely confirmation bias?
A study showed that rhinovirus replicates faster in cold temperatures so there’s that…
I’ve never believed there was a connection, unless you really stress your system. But I’m really curious if anyone has data.
Just a theory but cold temperatures may push people into spending more time indoors and in closer contact with other people. This would drive up infection rates.
The air is also drier when it’s cold out, and I’ve seen a pair of studies they found people more likely to catch respiratory bugs when the air is dry. But that’s just “it’s cold out”, not, “a person was cold”.
Was this the phrase that was used? I know what you’re asking, but “catching a chill” could mean catching an illness that gives you chills, like a fever, as opposed to catching an illness from being chilled. I.e. is the “chill” a cause or a symptom?
That makes a lot of sense - it isn’t necessary for your entire body to ‘be cold’ (because that’s hypothermia), just for the membranes that form the first line of defence to be cold.
Keats died of tuberculosis, which he almost certainly caught from his brother Tom – the sort of thing people in the early 19th century usually attributed to “catching a chill” in combination with some sort of hereditary predisposition. (You can be infected with TB for a long time before showing any symptoms, so it wasn’t obvious to people that it was contagious in the same way that, say, measles is contagious. They did observe that family members often took ill and died one after another over a period of months or years, as eventually happened with all three of the Keats brothers. Their sister Fanny, who wasn’t living with them at the time, was the only sibling to live to old age.)
I would be surprised if getting chilled affects the immune system enough to trigger a latent TB infection, although it’s plausible that having a cold or other viral infection might.
Cold alone probably isn’t enough to trigger respiratory infections, unless it’s so severe that you develop hypothermia, which can trigger a number of detrimental effects.
While some viruses replicate better in colder, dryer environments, and immune function might be compromised to some extent by cold, the evidence isn’t overwhelming.
It looks like colds and flu may be more prevalent in winter primarily because we’re indoors more and in closer contact with germy people.