The reviews and research papers I have found all indicate that CBD and delta-9-THC are immunosuppressive. In particular they suppress T-cell proliferation in response to antigen presentation - this is a bad thing. You want the T-cells to proliferate so that the immune response is stronger. There is no dose that appears to boost the immune system. The Medscape article you linked entirely discusses the immunosuppressive functions - lowering the inflammatory response so that people don't get something known as a cytokine storm. This is where the immune system releases cytokines, which are small signalling proteins that cause an inflammatory response. Too much cytokine production causes fluid leakage, swelling, etc. Notably this does not induce a T-cell response.
There's a good review here: https://www.ncbi.nlm...les/PMC4470840/. I am aware this is not CBD, but the usual "dosing" method of inhaling burning marijuana does not discriminate between CBD and Δ9-THC. CBD is of the same class of molecule (cannabinoids), and has the same responses in the literature that I could find.
Here's some quotes from section II: Effects of Δ9-THC on T-cells. Bolding in each case is mine.
Δ9-THC was also shown to depress proliferative responses induced by the Mixed Lymphocyte Reaction (MLR) of human peripheral blood T-cells exposed to allogeneic antigen presenting cells (Yuan et al. 2002) and murine spleen cells (Robinson et al. 2013).
A considerable number of studies examined which T-cell subsets were affected by the cannabinoid, and the mechanisms by which T-cell function was altered. Δ9-THC was found to differentially suppress the number of CD8 T-cells and reduce their cytolytic activity (Klein et al. 1991;Pross et al. 1990).
Cooperation between antigen-presenting cells, T-cells and B-cell is required. A number of laboratories had shown that Δ9-THC inhibited this antibody forming cell (AFC) assay. (Baczynsky and Zimmerman 1983;Eisenstein et al. 2007;Lefkowitz and Klager 1978;Smith et al. 1978;Watson et al. 1983).
Kaminski's laboratory showed that Δ9-THC given per os for 7 days differentially suppressed antibody responses to a T-dependent antigen, SRBCs, but not to a T-independent antigen, DNP-Ficoll, supporting the conclusion that the effect is on T-cells or on antigen-presenting cells that are needed for T-dependent responses.
Now on to CBD - CBD like other cannabinoids is immune-suppressive, it upregulates the CB1 and CB2 receptors, which induces T-reg upregulation (these are a suppressive form of T cells...). Below is a quote from this abstract. Note that responder T-cells are the "protective" ones.
Most importantly, the Us/o+CBD-induced CD4+CD25+ Tregs robustly suppressed responder T cell proliferation, demonstrating that the mechanism by which CBD is immunosuppressive under low-level T cell stimulation involves induction of functional Tregs.
How about this one, seeing as you are interested in vaccines - enhanced virulence of a vaccine = bad. Note that the vaccina (smallpox) vaccine is a live virus vaccine:
Considering a recent case of unusually severe cowpox virus infection in a young drug taker these data confirm a risk of "soft drugs" for acquiring poxvirus infection or enhancing side effects of the smallpox vaccine and perhaps also other live vaccines.
I am afraid to say that the OP in the first of your links is incorrect in their reading of the literature. Their quotes from links are missing substantial amounts in information, and seem to be focussing entirely on the word endocannabinoid, but missing the critical bit, which is what they actually do. As far as I can tell none of the links provided mention t-cell activation in response to infection, they all are talking about inflammation, and cancer largely. Here's a quote from one of the "footnotes" from the second post (note, I've gone for the pubmed link as this is more commonly used in the scientific community than the original archive.is - it's a free paper either way):
. We hypothesized that the intrinsic release of eCBs from immune cells during activation by pathogenic antigens mitigate inflammation, but also suppress overall innate and adaptive immune response.
Note that the innate and adaptive immune responses are to infection. The quote the OP provided from these articles were cherrypicked to have some key words, but lacked an understanding of the significance of the paper.