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 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 https://bit.ly/3zoCSAY 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
https://bit.ly/38icqN6 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.
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 One in four vaccinated LA
residents got COVID
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 https://bit.ly/2XWWZIx.
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." Click for a Reuters graphic https://tmsnrt.rs/3c7R3Bl
on vaccines in development.
(Reporting by Nancy Lapid; Editing by Tiffany
Wu)
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