The voluntary consent of the human subject is absolutely essential. This means that the person involved should have legal capacity to give consent; should be so situated as to be able to exercise free power of choice, without the intervention of any element of force, fraud, deceit, duress, overreaching, or other ulterior form of constraint or coercion; and should have sufficient knowledge and comprehension of the elements of the subject matter involved as to enable him to make an understanding and enlightened decision.

Bert Hubert’s excellent and widely shared article about Reverse Engineering the source code of the Pfizer-BioNTech SARS-CoV-2 Vaccine

Translational kinetics of mRNA-LNP delivered by different routes in vivo. Quantification of the bioluminescent signal measured in BALB/c mice injected with (A) 0.1 μg, (B) 1.0 μg or (C) 5.0 μg mRNA-LNPs by intradermal (i.d.), intramuscu

In this mouse model, the mRNA hit the hepatocytes and caused them to make plenty of luciferase, but not for long: at Day 1, the livers were lit up like a used car lot, but by Day 3, everything was gone. At that point, though, there was still some light coming from the sites of injection.

Δώστε ένα πακέτο στα μίνιονς του Kaiser και εύχομαι το billions να είναι ΚαλοPfizer Και όταν θα επέλθει η ανοσία στην αγέλη θα δούμε πόσες μέλισσες θα υπάρχουν στην κυψέλη και εν τέλει

Thus, this study provides the basis to pursue further efficacy studies in non-human primate models or even initiate clinical phase I studies using the currently available vaccines.

The exact time is not known, but it is estimated to be a few weeks. 

Following IM administration, the maximum concentration (Cmax) of the injection site muscle was 5,680 ng/mL, and the level declined with an estimated t1/2 of 18.8 hr

The spleen and liver had a mean Cmax of 86.9 ng/mL

Proximal lymph nodes had the second highest concentration at 2,120 ng/mL (tmax of 8 hr with a relatively long t1/2 of 25.4 hr)

Current injectable vaccines induce a systemic immune response by generating circulating IgG antibodies that neutralize pathogens before they can cause severe tissue damage. But IgG is not very good at controlling viral entry into the body. To do that, the mucosal immune system is needed. It produces secretory IgA at the site of viral entry, and in larger quantities than any other type of immunoglobulin in the body.

The Astra-Zeneca shot uses a modified chimpanzee adenovirus as vector. These viruses use the CD46 receptor instead of the usual CAR receptor for infecting cells. “We found that human umbilical vein and brain microvascular endothelial cells (HUVECs and HBMECs) were CD46-positive”

The Hsieh et al, Science, 2020 paper on HexaPro also notes that the HexaPro mod and the S-2P mod have the same ACE2 affinity (although they don’t make the comparison to wild-type). (Note that the conformational change upon binding is all about assisting viral entry into the cell, not binding the ACE2 receptor.)

Inadvertent injection into blood vessels has been raised in the comments here previously