Re: carbon monoxide poisoning
Since it's been a couple of months since your CO scare, I hope someone has fixed the cause of the leak. In January, it was most likely your heater, or a supplementary heater, or some internal combustion engine (like a home generator) running inside the house or inside an attached garage. It is most important to find and eliminate the cause of the carbon monxide. (It could even have been from a temporary activity like running gas/diesel floor sanders, waxers, etc,). Or, even use of unvented gas heaters that are poorly adjusted on their fuel/oxygen mix. If you are unsure, call the gas company of an industrial hygienist, or safety company to check for you. And you were smart to have a CO alarm.
As to any long term effects to humans, the answer is probably no. Your body does not have a means of storing CO. It just does it's damage and goes away. The main dangers to worry about are if you are any of the victims were pregnant during the exposures. There are cases of fetal brain damage when the mother was overexposed to CO and collapsed. The mother was not harmed in particular, but the baby (born later) was. If a pregnancy was involved, you should talked to your OB GYN about this. Amount of damage may be related to mom's exposure.
The last ways CO can be harmful is it can be immediately toxic. In other words you "wake up dead". Or you are in a place where you pass out, fall, and have a injury that can in itself be harmful. Keep in mind that for years OSHA allowed factories to have 50 ppm of CO in factory air. Most authorities now have lowered that number to as low as reasonably possible.