How likely are you to catch Covid twice?
Eventually, pretty likely - immunity fades and viruses evolve.
Fewer than 1% of all cases recorded in the UK before November 2021 were reinfections.
But Omicron's different structure gives it a better chance of sneaking past the body's early defences, which were based on exposure to previous Covid strains.
So the rates of reinfection have been about 10 times higher this year compared with rates seen earlier in the pandemic.
This new "Spring" Omicron - known as BA.2 - drove UK infections back up to record levels.
The Office for National Statistics said about one in 13 people in the UK had Covid in the week ending 2 April, although this had dropped to about one in 15 by the week ending 9 April.
This had fallen again to about one in 17 by the week ending 16 April.