My guess is that the vaccine was a wild one which had been brought in for study to the research laboratory. My further guess is that it escaped not because anyone caught it, but because the laboratory animals are routinely sold off to the local market traders instead of being incinerated, as a perk of the job for under-paid technicians. Although this seems to have been a laboratory-induced pandemic, poor agricultural and food handling practices are another important contributor to pandemics generally, including living too close to animals and crowding animals together unnaturally.
Once pathogens get into human populations, Darwinian natural selection applies. The most contagious ie the mildest version survives. It does not help the virus to spread if it kills, or sends to bed, whoever it infects. Although we will not know for another couple of weeks, the omicron mutation seems to be the end of the road for this virus. If the virus is no more dangerous than a common cold, as seems likely on the evidence so far, lockdowns, passports and booster vaccines are exactly what should not be applied; it seems as if we have a natural vaccine and it should be encouraged to spread as fast as possible.
The poor outcomes from the original version of Covid seem to have been due largely to the pre-existing epidemic of malnutrition, including overweight and vitamin deficiency. Nobody in authority seems to want to talk about these issues.
Throughout the course of the epidemic, Dr John Campbell has made video reports almost every day. He is
worth following. Unfortunately, politicians and commentators seem mostly not to have taken on what he has been saying.
Covid is probably over but there will be other pandemics. Action needs to be taken to reduce the risk, and everyone needs to be better prepared. The root causes need to be tackled.