| MOPV | monovalent oral poliovirus vaccine |
|---|---|
| OA | obstructive apnea; occipital artery; occipito-anterior; occiput anterior; octanoic acid; ocular albi... |
| OA/BVM | oral airway/bag-valve-mask |
| OAS | old age security; oral allergy syndrome; osmotically active substance |
| OAW | oral airways |