SARS-CoV-2 vaccines: Much accomplished, much to learn

Scientists with NIH’s National Institute of Allergy and Infectious Diseases (NIAID) note that while they have gleaned useful information on the first coronavirus vaccines to be distributed publicly, there is still a huge learning curve to navigate. Rare and very seriously adverse effects, for instance, typically do not come to light until after millions of people have been immunized. In addition, while most adverse events occur in the early weeks and months after vaccination, longer-term effects cannot be ruled out. Another question that will continue to demand close attention is the extent to which vaccines protect against infection and transmission, as well as the duration of that protection. Special populations—including children, expectant mothers, individuals with underlying conditions, and people on medications that might influence immune response to vaccines—represent another significant concern and consideration. While the data is trickling in from Pfizer and Moderna’s vaccines, both of which are messenger RNA (mRNA) based, FDA emergency use authorization is likely in the pipeline for AstraZeneca, whose candidate is based on a chimpanzee-derived adenovirus, and for Johnson & Johnson/Janssen, which is using a human adenovirus. Beyond that are prospects from Novavax and Sanofi/GlaxoSmithKline, both of which are produced using recombinant baculovirus. “Acknowledging that there is still much to learn while strongly encouraging vaccination is arguably one of the most critical challenges facing health care providers today,” the NIAID colleagues write. “Having a clear understanding of the data supporting the use of these new vaccines is critical to addressing that challenge.”