While millions of people in dozens of countries have received the AstraZeneca Covid vaccine with few reports of ill effects, and its prior testing in tens of thousands of people found it to be safe, the vaccine is being investigated. A New York Times article explains the decision to pause the vaccine in European countries, with concerns about blood clots and abnormal bleeding in a small number of vaccine recipients. Stephan Moll, MD, professor of medicine in hematology, and David Wohl, MD, professor of medicine in infectious diseases contributed perspective to the article.
“The United States has 253 million adults,” said Moll. “So, if every day 2.3 million people in the United States get Covid-vaccinated, that means about 1 percent of the adult population gets vaccinated every day.”
Calculating further, he said, roughly 1 percent of the 1,000 to 2,000 daily blood clots — 10 to 20 a day — would occur in the vaccinated patients just as part of the normal background rates, not related to the vaccine.
“Only if epidemiological data shows that that rate is higher, would one start to wonder about a causative relationship.”
Wohl concurred, adding that he had not seen evidence that any of the Covid vaccines had caused blood clots, also called thrombosis, in the large clinical trials that led to their authorization. But he also noted, “There are differences between trials and real life.”
Read the full New York Times article here.