Developments in vaccines / drug safety

[R7ehr]

Back in Covid-19 times, I got the J&J shot instead of the Moderna or Pfizer, because I was more comfortable with the old fashion vaccine technology than the MRNA.

“SCIENTISTS FIGURED OUT THE PROBLEM WITH JOHNSON & JOHNSON’S COVID VACCINE”

“Rare but dangerous blood clotting associated with that vaccine as well as AstraZeneca’s had a genetic cause, according to a new paper.”

By Roxanne Khamsi

In 2021, just months after the first COVID vaccines debuted, concern was growing about an exceedingly rare but sometimes deadly outcome of certain shots. Two related vaccines—one from AstraZeneca and the other from Johnson & Johnson—were linked to dangerous blood clotting.
Out of almost 19 million doses of Johnson & Johnson’s version given in the United States during the first two years of the pandemic, at least 60 such cases were identified. Nine of them were fatal. In the United Kingdom, where almost 50 million doses of the AstraZeneca shot were given, 455 cases occurred; 81 people died. In Germany, at least 71 cases were identified, also linked to AstraZeneca. By late spring, use of both the AstraZeneca and the Johnson & Johnson vaccine was paused, and ultimately both were pulled from the market. But the mystery surrounding the rare blood clotting caused by these vaccines lingered.”

“In the study, Greinacher and his colleagues looked at the antibodies in stored blood from 21 patients with VITT. Among those antibodies, they found a subset that could glom on to a portion of the adenovirus and to one of the body’s own molecules, PF4, that can influence blood clotting. A person who received one of the adenovirus vaccines but did not have a reaction also had antibodies against that same part of the adenovirus. But, crucially, that person’s antibodies did not cross-react with PF4.
Those antibody molecules also offered clues about the immune cells that made them. And the scientists were able to link the immune cells responsible for VITT to patients who had two specific DNA variants. A wider survey of 100 VITT patients found that all of them had immune cells with one of these genetic types—which are far from universal. This signaled to the researchers that having these particular variants is a strong risk factor for blood clotting following an adenovirus vaccine.
But the study also showed that this genetic background on its own was not enough to cause VITT. The immune cells that made the dangerous antibodies had experienced an additional small genetic change, and that extra mutation had prompted them to produce those cross-reactive molecules.”

“These results also mean that adenovirus-based vaccines could be made safer if they can be designed without the protein region that triggered the dangerous antibodies in VITT. “Instead of abandoning an entire vaccine platform because of a rare problem, we can engineer around the specific issue, and that’s the power of this kind of science,” Joann Arce of the Precision Vaccines Program at Boston Children’s Hospital told me. The hope is that understanding the biology of a rare event like VITT, and then addressing it, helps bolster public trust in vaccines too. Greinacher told me that adenovirus-based vaccines remain vital, including for the development of vaccines for diseases that affect mostly low- and middle-income countries. The shots could also be useful in a future pandemic, because they can be scaled up in production relatively quickly.
Still, this one study may not have entirely answered the question of why adenovirus-based COVID vaccines caused clotting. A study published last year from Ju’s group suggested that a separate biophysical mechanism might cause a viral component found in the AstraZeneca vaccine to directly aggregate platelets, independent of the immune reaction identified in VITT. And a bigger mystery remains open too—why infections themselves are sometimes associated with dangerous blood clotting. Rushad Pavri, an immunologist at King’s College London, told me that the new study—because it shows how similarities between a virus particle and an innate protein involved in clotting can confuse the immune system—can shed light on that question. Ultimately, understanding why viruses can provoke immune overreactions might help limit damaging complications from sickness to begin with.”

https://apple.news/A4C2w4eUFQWKydc2fGaP-_g