How easy are they to manufacture?

Once a pathogen’s genome has been sequenced, it is relatively quick and easy to design a vaccine against any of its proteins.  For instance, Moderna’s RNA vaccine against COVID-19 entered clinical trials within two months of the SARS-CoV-2 genome being sequenced. This speed could be particularly important in the face of new emerging epidemic, pandemic pathogens or pathogens which are rapidly mutating.