Late October/early November last year we had the worst virus we can remember having as adults in this household (we're in our late 40s/early 50s).
We nicknamed it the Zombie Flu as it took around 6 weeks to go in total. You would just think it had gone and it would rear its hideous head again in a slightly different form. Neither of us are particularly prone to colds and 'flu in general. This was so bad that for the first time ever I debated paying for the 'flu jab.
Partner is a nurse (elderly care mainly although not in an NHS hospital, in the care home system locally, we live in a beautiful, rural part of England with a warm, if wet, climate, that has quite an elderly demographic overall - we both used to work for the NHS, them on the nursing side and me in admin/learning), and thinking back, they remember someone who had been working in China visiting their ill parent in the home they were working at, around the same time as we got sick. Many members of staff there got sick at the same time and we both remember it happening very quickly. And we're used to the drill of making sure clothing is changed, stuck in the washing machine at 60 degrees at least, items sanitised, gloves etc if there's been any contact with anything horrid, but this still got through.
That's as much as we can remember at the moment about the probable rate of transmission (we've had a couple of bereavements since and other family stuff to deal with too) but this was a virus like no other either of us had come across. And they grew up and trained in South Africa, so they're used to working in a resource poor environment where infections are endemic.
The only other time, as an adult, I've been quite as ill as we were last autumn was when I taught English (high school level) for a couple of years in the Far East. And I was 30 years younger then, so threw it off much faster.
I've never had headaches like it; I honestly thought it was the beginning of a brain tumour. We weren't particularly snotty or sneezy, but our coughs were so bad I think we tried every brand of cough mixture available on the market, plus our own concoctions of honey and lemon and whisky (that went down like a lead balloon, when I used the good Bushmills and the even better limited edition Scotch....). We also tried other ways of combating it (steam inhalation, Olbas oil, Vicks, every aromatherapy oil I knew was safe, menthol crystals dissolved in hot water, mini-nebuliser, you name it). We found our temperature fluctuated a lot as well - we did buy a very basic thermometer, but again, having trained in South Africa, they're very good at being able to do observations we've largely lost the knowledge of here. We've become so reliant on technology.
Although we both have underlying chronic health conditions they're not respiratory; my dad had very bad lung problems but he didn't pass them on to me.
I'm not saying what we had was what they're now calling COVID-19 by any means, but the first COVID-19 case(s) was/were NOTIFIED to the WHO at the end of December last year. When the antibody tests are available I would be interested to be tested if the possibility was there (but obviously not ahead of someone who really needed it).
Just a shout out here for all the medics and nurses and delivery people and teachers and everyone else doing an amazing job at keeping us all going, and good thoughts and (suitably socially distanced) hugs to everyone else.