When a vaccine is used 3 days before its expiration it still effective?
Some vaccines may lose their potency after the expiration date, while others may still be effective for a short time. It is important to follow the manufacturer's instructions for storage and use of vaccines.
In general, it is not advisable to use a vaccine after its expiration date, as there is no guarantee of its effectiveness or safety. If you are unsure about whether or not a vaccine is still effective, it is best to consult with a doctor or pharmacist.