ps. Third, depending on company & product lot: the mRNA-LPN may be contaminated with weird, inappropriate DNA fragments (toxins) from RNA manufacturing process.
It's been proven that the product lots which show up for injection into people, are different & sometimes more contaminated than the nice clean product lots which that company sent in for government approval.
Pfizer was nailed last month:
We...identified large amounts of DNA after RNase A digestion in all lots with concentrations ranging from 32.7 ng to 43.4 ng per clinical dose. This far exceeds the maximal acceptable concentration of 10 ng per clinical dose that has been set by international regulatory authorities...including the SV40 promoter/enhancer
"SV40 promoter/enhancer" means: contamination that will cause cancer.
Do not assume other companies are better.
BUT, this factor applies to mRNA vaxx in mass production (covid). For RSV clinical trial (thread topic), company probably sent in clean lots. So, RSV trial problems would be the other problems, stated earlier.