And the greater problem with science communication regarding intramuscular vaccines, and the political theater surrounding it, is that neither "side" actually gives the full story because they worry nuance would be lost and facts without context used against them.
Yes, intramuscular vaccines for sars-cov-2 work, for about 6 months, to significantly reduce the likelyhood of serious disease in the internal organs. They do this by getting your body to produce serum igG antibodies against the shape of the spike protein produced, or delivered, by whatever mechanism. They also train your T cells to recognize more broad coronavirus epitopes that hold up longer against changes in spike coding.
But the igG antibodies in the body serum produced by intramuscular vaccination do not appear in any useful quantity in the upper respiratory mucosa (a different immune compartment). And the T cells definitely do not get there. The upper respiratory mucosa is where respiratory viral diseases infect. Intramuscular vaccination does not protect against sars-cov-2 infection of the upper respiratory mucosa. It just means that your lungs, which have some serum igG antibodies seep in, are protected and your body organs are protected. You can and do still get infected and transmit the virus to others at the same rate as the un-intramuscularly vaccinated.
The intramuscularly vaccinated should not be exempted from any mask requirements and people really, really have to become aware of this if we're going to stop the pandemic. It's either that or intranasal vaccination, the smart move, like India is pushing towards. Enough of the intramuscular boosters. We need intranasal to stop the spread.
Pretending intramuscular vaccination is some be all end all that stops spread is stupid and deadly. It is only the first partial step.