They have no idea how long antibodys last either natural or from the vaccine as this virus has not been studied for very long outside of China. The western medical world has only known of it since about feb or mar
No reason to believe it won’t behave like most other similar viruses which would put it right around a a year to 18 months. I base this off I from my sister in law who works in research in pharma and is currently working in covid albeit on the testing side.
