The earliest we are likely to see a second wave is probably October, but only if cases go unchecked and unmonitored.
Oh.
Shit.
Remember scientists think it took approximately 4 months from arriving in the UK to the peak in April, but it remained undetected from UK community transmission until early March.
Realistically that means November / December are going to be interesting, especially with a 31st December deadline looming over imports etc.
A second wave in the UK which isn't replicated in the EU would be devastating in more ways than one - it would effect labour availability and disaster planning. And that's without all the other possible issues.
This is a worst case scenario but we could be looking at something WORSE than no deal Brexit.
Bet you didn't imagine that at the end of last year. We thought it possible that a hostile nation could try and create trouble, but this surpasses that.
Also don't forget a no deal strategy rests heavily on US (Trump) support, and we have an election in November. And the domestic situation in the US is looking 'interesting' and we might find huge shifts in focus, massive unrest and/or a change in government.
A perfect storm of shit is potentially brewing.