Vaccines against sudden acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are designed to elicit immune responses that prevent recipients from getting — or becoming seriously ill or dying from — novel coronavirus disease (COVID-19). Two available COVID-19 vaccines are based on genetically engineered messenger RNA (mRNA). After administration, such molecules give muscle cells “instructions” for how to make target proteins — e.g., the SARS-CoV-2 spike (S) protein. Immune-system detection of those proteins prompts creation of neutralizing antibodies. Immediately upon delivery of…