Ricki Lewis

Most of us have an intuitive understanding of how a vaccine works: show the immune system a bit of a pathogen, or something mimicking it, and trick it into responding as if natural infection is happening. The COVID-19 pandemic ushered in a flood of vaccine options.

When I was writing "How the various COVID vaccines work," which ran here at DNA Science on September 10, I had to keep reviewing summary charts to remember who was doing what. Vaccine technology has gone beyond live, weakened, or killed virus, even past the once-groundbreaking subunit vaccines that present parts of a pathogen, like the hepatitis B surface antigen or pertussis toxin. Now we have DNA and RNA vaccines too, delivered in different ways.

The first two vaccines against COVID-19, Tozinameran (the Pfizer/BioNTech vaccine) and mRNA-1273, Moderna's still unchristened candidate on the brink of emergency use authorization, are mRNA. And that's confusing people, based, perhaps, on when they took high school biology (more on that coming). So here's a brief consideration of mRNA and how it can alert the immune system to fight SARS-CoV-2.

To continue reading, go to my blog DNA Science at Public Library of Science.

In ordinary times, a new report describing experiments on bits of smallpox scabs nestled in Civil War museum artifacts would have been mildly interesting. But these days, clues in old poxvirus genomes are especially intriguing because they may explain how some people resist COVID-19, perhaps thanks to a past run-in with a different coronavirus. According to another recently published study, these individuals haven't tested positive for COVID-19 or SARS or had contact with people who have, yet they have immune memory – T cells that recognize a coronavirus that infects bats.

Could exposure to one type of coronavirus protect against infection by another?

"The origins and genomic diversity of American Civil War era smallpox vaccine strains," published in Genome Biology, looks at a possible precedent to answer that question. Such cross-reactivity happens when an antibody or T cell recognizes a surface molecule common to more than one species of pathogen. It's a little like recognizing Eric Clapton in different bands.

A Brief History of Smallpox Vaccination

To continue reading, go to DNA Science, where this post first appeared.