mRNA vaccines trigger backup immune response; some cancer drugs may help
August 25, 2021; 5:12 PM EDT (Updated August 26, 8:19 AM EDT)
Antibodies wane but other immune defenses remain alert
A new study may help explain why mRNA vaccines by Pfizer/BioNTech and Moderna are more effective at preventing hospitalizations and deaths than they are at preventing infection. Test-tube experiments on blood samples from 61 fully vaccinated adults showed that by six months, vaccine-induced antibodies that can immediately neutralize the virus had declined. But so-called memory B cells, which produce new antibodies if they encounter the virus later on, had increased and become better at recognizing viral variants, according to a report posted on Monday on bioRxiv ahead of peer review. “Your immune system has a backup,” said study leader John Wherry of the University of Pennsylvania Perelman School of Medicine. B-cell production of antibodies might take a few days to get underway, but then these memory B cells “kick into action and prevent severe disease,” Wherry added.
Early data favors certain cancer treatments during pandemic
Certain cancer drugs may help protect patients with malignancies from being infected with the new coronavirus, preliminary data suggests. The drugs, known as mTOR/PI3K inhibitors and antimetabolites, target the parts of cells that the virus uses to enter and make copies of itself, including a “gateway” protein on cell surfaces called angiotensin-converting enzyme 2 (ACE2). The study of 1,701 cancer patients found that after taking underlying risk factors into account, patients treated with mTOR/PI3K inhibitors or ACE2-lowering antimetabolites were 47% less likely to test positive for the virus than patients who received other drug therapies. Gemzar (gemcitabine) from Eli Lilly appeared to be particularly promising, according to the report in JAMA Oncology on Thursday. The study does not prove that the drugs lowered infection rates, however, and much more research is needed to confirm their potential for protecting cancer patients from the coronavirus.
One in four infected LA residents had been vaccinated
From May through July 2021, as the Delta variant spread, 43,127 residents of Los Angeles County in California were diagnosed with SARS-CoV-2 infections. One in four had been fully vaccinated, though these patients had lower rates of hospitalization (3.2% versus 7.6%), intensive care (0.5% versus 1.5%) and need for machines to help with breathing (0.2% versus 0.5%) than unvaccinated patients, public health officials reported on Tuesday in the U.S. Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report. During the study period, the prevalence of the Delta variant rose from less than 9% to at least 87%, the authors note. As of July 25, hospitalization rates were 29 times higher for unvaccinated patients, they estimated, “indicating that COVID-19 vaccination protects against severe COVID-19 in areas with increasing prevalence of the SARS-CoV-2 Delta variant.”
(Corrects third sub-head on infection rate of vaccinated LA residents)
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