Ask the Past: avoiding Covid

I'm going on my first holiday in ages next week, and I'm worried that I'll catch Covid and have to miss it. Do you have any tips for avoiding infection?

Unsurprisingly, none of the books I looked at can offer any suggestions for avoiding Covid, but I found a lot of books that talked about colds and flu. Unfortunately, it also seems like most of them had no idea where the flu came from. According to the entry on influenza in Domestic Medical Practice (1913):

Although the facts of its prevalence indicate a poison as its cause, we do not not what that poison is, nor the special circumstances of its production.

Even so, there were remedies out there. The lady's every-day book (1880) has this suggestion for avoiding catching a cold that is bound to be useful:

Protecting the back with wash-leather or flannel, should be well observed by those who would avoid catching cold. Many persons are not aware that it is quite as necessary to protect the back between the shoulders, and especially under the blade bones, where the lungs come near the surface, from cold and draughts, as it is the chest.

Harmsworth's Household Encyclopedia (1922) has slightly more up to date suggestions:

As influenza patients rarely confine themselves to the house until they are forced to do so, opportunities are not lacking for communicating the disease to others. Some good might be done by not breathing directly into other people's faces. Pure air is a first consideration, and those who can keep in the open air diminish their risks. Respirators have the disadvantage that they become hot and perhaps unwholesome. Washing out the throat and nose with a weak solution of permanganate of potash has appeared to be effective in some cases. There is no specific drug, but a dose of ammoniated tincture of quinine, 1/2 dram, twice or thrice a day may be worth trying.

And finally, here's a useful piece of advice from the 23 July 1931 edition of the Poverty Bay Herald

Don’t stop smoking if you have a cold. Dab “NAZOL” on your cigarettes—it clears the lungs.

I'm sure that will help.