The path to herd immunity is tricky.
Both Pfizer-BioNTech and Moderna's COVID-19 vaccines trigger a consistent immune reaction in the human body that could protect recipients for years, according to a Monday report from the journal Nature.
While the effectiveness of drugs developed at world-record speeds at such an early stage is naturally tenuous, we may be nearing the stage where many vaccine recipients may breathe a sigh of world-historical relief.
However, with troubling developments amid Israel's Delta variant outbreak, there may still be cause for concern.
COVID-19 coronavirus immunity might last for years
The new findings lend credence to mounting evidence that most people who receive the two mRNA vaccines may need no further boosters, as long as the virus and its subsequent variants don't surpass an evolutionary threshold of potential effectiveness. And to be clear: this could happen. Those who contracted and survived the COVID-19 coronavirus before receiving a vaccine might be fine without a booster, even should the virus undergo a substantial evolutionary leap. "It's a good sign for how durable our immunity is from this vaccine," said Ali Ellebedy, a Washington University immunologist in St. Louis, who was also the lead author of the study, in a report from The New York Times.
However, the study didn't involve Johnson & Johnson's vaccine, but Ellebedy also said the immune response to this vaccine will likely be less durable than the one created via mRNA vaccines. Last month, Ellebedy and his study colleagues reported that COVID-19 survivors' immune cells identified a dormant version of the virus in bone marrow for up to eight months after the initial infection. Another team's study suggested that memory B cells see ongoing maturation and gain strength for at least one year post-infection.
These findings showed that immunity could last years, and perhaps an entire human lifespan for those who contracted the virus before receiving a subsequent vaccination. But without having first contracted the virus, this ongoing immunity might not hold up. To evaluate this possibility, Ellebedy and his team looked at the source of memory cells: the lymph nodes, which is a kind of training grounds for immune cells.
COVID-19 Delta variant may still pose some concern for Pfizer recipients
Once an infection or vaccination has occurred, a relatively unique structure called the germinal center coalesces in the lymph nodes, functioning like an advanced progress class for B cells, where their ability to effectively identify and target a wide array of viral genetic sequences is honed. The wider the scope of training and practice these cells have within the lymph nodes, the better equipped they are to combat future variants of the COVID-19 coronavirus. "Everyone always focuses on the virus evolving -- this is showing that the B cells are doing the same thing," said a University of Washington immunologist Marion Pepper, in the NYTimes report. "And it's going to be protective against [the] ongoing evolution of the virus, which is really encouraging."
This is crucial because, with every new infection, the coronavirus evolves, with a potential to transform into a mutation too powerful for some forms of immunity to thwart. Days ago, a report from the Wall Street Journal suggested that the Delta variant of COVID-19 illness might still infect those who had received the full, two-dose Pfizer vaccine, with roughly half of adults infected amid the Delta variant outbreak in Israel already ostensibly immune to the virus. Suffice to say that both the Pfizer and Moderna variants may provide long-term immunity, but for those who didn't previously contract the virus, this might not be the case.