Naumova EA, Dierkes T, Sprang J, Arnold WH. The oral mucosal surface and blood vessels. Head Face Med. 2013 Mar 12;9:8. doi: 10.1186/1746-160X-9-8. PMID: 23497446; PMCID: PMC3639856.
It also has antibodies (humoral immune response).
Immunoglobulin A (IgA) is the most abundant antibody isotype in the mucosal immune system.
Li Y, Jin L, Chen T. The Effects of Secretory IgA in the Mucosal Immune System. Biomed Res Int. 2020 Jan 3;2020:2032057. doi: 10.1155/2020/2032057. PMID: 31998782; PMCID: PMC6970489.
And the vaccine triggers the development of those antibodies.
We evaluated the serum anti-spike (anti-S) IgG, anti-nucleocapsid (anti-N) IgG and anti-S IgA response following vaccination against SARS-CoV-2 in a cohort of first-responders. Among the 378 completely vaccinated participants, 98% were positive for anti-S IgG and 96% were positive for anti-S IgA.
Montague, B.T., Wipperman, M.F., Chio, E. et al. Elevated serum IgA following vaccination against SARS-CoV-2 in a cohort of high-risk first responders. Sci Rep 12, 14932 (2022). https://doi.org/10.1038/s41598-022-19095-7
While I can completely and utterly understand the medical profession's careful monitoring of a situation, particularly when it comes to negative birthing outcomes in the US, the first response should not be the vilification of parents until they are 1099% sure they have evidence that supports such action.
But, then again, when we had our first kiddo and she received an incorrectly inserted epidural there wasn't even a single apology from anyone, let alone the anesthesiologist who let the epidural leak into her skin, eventually puffing up the skin to a noticeable bubble, rather than where it was supposed to be, leaving her in excruciating pain to the point where I had to scream at the nurse's station for 45 straight minutes until someone would listen instead of just telling me she was fine and we were overreacting. Or the doctor who was stitching her up afterward, lacking any and all bedside manner, by saying he should have taken a before and after photo of her vagina, in front of me and my wife, because he had done such a great job.
When it came to our stay in the NICU: we were asleep in a room on another floor, our first in 40+ hours, they performed surgery on our daughter w/o asking our permission or informing us first because they attempted to call the room we were in but we didn't answer--only later to find out that the room's phone had been removed and wasn't there. No one thought to come to the room or even call the nurses' station literally next to the room to have them ask/inform us of the surgery first.
But, sure, go ahead and add on immense stress in one of the most stressful situations of our lives through false accusations while protecting your doctors to the nth degree.
Again, just from what I have seen at county where substance use is a pretty banal, common occurrence and CPS often placed children in foster care straight from the newborn nursery.
I'm sorry that you had such a negative experience. Maybe it was at a hospital that doesn't deal with substance use issues much?