AstraZeneca vaccine is 79% effective, blood clots not detected in US study, Bay Area doctors say

SAN FRANCISCO (KGO) -- On Monday AstraZeneca released preliminary data that shows it's 79% effective in preventing symptomatic COVID-19 and 100% effective against severe disease and hospitalization.

"I think that really establishes this vaccine is out there with the other existing vaccines as extraordinary effective," said Dr. Annie Luetkemeyer, UCSF Professor of Medicine & Infectious Diseases and HIV.

UCSF's Dr. Annie Luetkemeyer and Dr. Susan Buchbinder with the San Francisco Department of Public Health, were both involved in the three Bay Area AstraZeneca trials. This is the part that excited Dr. Buchbinder, "100% is against severe disease hospitalization and deaths. So that's very good news."

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The safety efficacy analysis of this trial was based on over 32,000 participants in the U.S, Peru and Chile.

"The study has been monitored by data safety monitoring board or DSMB very closely. And it's the same DSMB that is monitoring many of the other studies. Thus far, there have been no concerns about safety," said Dr. Luetkemeyer.

According to Dr. Luetkemeyer, 20% of people who were enrolled in the trial were over the age of 65 and added " It's 80% effective in preventing symptomatic disease in people over the age of 65."

Multiple European countries stopped the use of AstraZeneca after 18 out of 2 million people reported blood clots in the brain in the U.K.

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"It was an extremely rare event," said Dr. Buchbinder and added, "They found that there were actually more in the placebo arm than there were in the vaccine arm. So there was no excess rate of blood clotting in the vaccine trial itself."

Dr. Buchbinder highlighted that the AstraZeneca vaccine trains the body, so if you are later exposed to COVID "you will recognize it and clear it out of the system effectively."

Luz Pena: "Is there anything particularly from the AstraZeneca vaccine that might be causing these blood clots?"

Dr. Luetkemeyer: "If you just look at millions of people you will find that people will get blood clots so there is not something specific that I think is different about AstraZeneca. There are some small differences between all these vaccines some have to do with the type of envelope that it uses and the DNA information is delivered."


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Researchers in Norway and Germany found that the AstraZeneca vaccine could potentially trigger an autoimmune reaction leading to these clots.

"I think that is a hypothesis that those researches have, and we do know that coronavirus in general can be associated with a robust immune response including some autoimmune response. I really think it's too soon to say with certainty," said Dr. Luetkemeyer.

Both doctors agree that based on the U.S data, this vaccine is effective no blood clots have been reported in the U.S trials.



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