re "Of the approximately 15,000 who had received one shot and got infected, about 50 died. Among almost 2,000 fully vaccinated people, only four died from the disease, showing a case fatality rate of 0.21%."
Note: I got the Pfizer two-shot sequence earlier this year. Due to the highly contagious Delta variant, I'm also wearing an N95 mask when I'm out shopping etc...
Study shows why second dose of COVID-19 vaccine shouldn’t be skipped
med.stanford.edu
A different type of vaccine
The Pfizer vaccine, like the one made by Moderna Inc., works quite differently from the classic vaccines composed of live or dead pathogens, individual proteins or carbohydrates that train the immune system to zero in on a particular microbe and wipe it out. The Pfizer and Moderna vaccines instead contain genetic recipes for manufacturing the spike protein that SARS-CoV-2, the virus that causes COVID-19, uses to latch on to cells it infects.
In December 2020, Stanford Medicine began inoculating people with the Pfizer vaccine. This spurred Pulendran’s desire to assemble a complete report card on the immune response to it.
The team selected 56 healthy volunteers and drew blood samples from them at multiple time points preceding and following the first and second shots. The researchers found that the first shot increases SARS-CoV-2-specific antibody levels, as expected, but not nearly as much as the second shot does. The second shot also does things the first shot doesn’t do, or barely does.
“The second shot has powerful beneficial effects that far exceed those of the first shot,” Pulendran said. “It stimulated a manifold increase in antibody levels, a terrific T-cell response that was absent after the first shot alone, and a strikingly enhanced innate immune response.”
Unexpectedly, Pulendran said, the vaccine — particularly the second dose — caused the massive mobilization of a newly discovered group of first-responder cells that are normally scarce and quiescent.
First identified in a recent vaccine study led by Pulendran, these cells — a small subset of generally abundant cells called monocytes that express high levels of antiviral genes — barely budge in response to an actual COVID-19 infection. But the Pfizer vaccine induced them.
This special group of monocytes, which are part of the innate museum, constituted only 0.01% of all circulating blood cells prior to vaccination. But after the second Pfizer-vaccine shot, their numbers expanded 100-fold to account for a full 1% of all blood cells. In addition, their disposition became less inflammatory but more intensely antiviral. They seem uniquely capable of providing broad protection against diverse viral infections, Pulendran said.
“The extraordinary increase in the frequency of these cells, just a day following booster immunization, is surprising,” Pulendran said. “It’s possible that these cells may be able to mount a holding action against not only SARS-CoV-2 but against other viruses as well.” |
