• Elie Dolgin

Pamela Sherry is eager to become immunized against COVID-19. But she has put off getting a jab.

“I believe vaccines work,” she says. “I want the protection.” Yet she is prone to acute immune reactions and has blood circulation problems, so she has concerns about the shots available in the United States, where she lives — those based on messenger RNA (mRNA) and viral-vector technologies. Although safe for most of the population, they have been linked to rare but potentially severe side effects, including heart inflammation and blood clots

So Sherry has been waiting for the menu of vaccine options available to her to expand. In particular, she is holding out for a vaccine built from purified proteins. Unlike the relatively new technologies that the mRNA and viral-vector COVID-19 shots are based on, protein vaccines have been used for decades to protect people from hepatitis, shingles and other viral infections. To elicit a protective immune response, these shots deliver proteins, along with immunity-stimulating adjuvants, directly to a person’s cells, rather than a fragment of genetic code that the cells must read to synthesize the proteins