AstraZeneca’s COVID-19 vaccine is 74 percent effective in preventing symptomatic illness, according to data from its U.S. clinical trial published in the New England Journal of Medicine on Wednesday.
The phase 3 trial involved more than 32,000 participants in the United States, Peru, and Chile, who either received two doses of the COVID-19 vaccine or a saline injection four weeks apart. However, data was based only on 26,212 participants.
The vaccine’s overall effectiveness of 74 percent was slightly lower than the initial analysis of 76 percent reported earlier in March by the drugmaker. But the vaccine was still 100 percent effective against severe or critical disease as no cases were observed in the fully vaccinated group compared to eight in the placebo group.
Participants in the vaccinated group experienced more solicited adverse events, which were “mostly mild or moderate and were fewer in number after the second dose,” within 28 days than those in the placebo group (40.6 percent versus 29.7 percent). However, the number of occurrences of adverse events requiring medical attention or of special interest were similar in both groups.
Researchers of the study said there were no cases of a rare but serious blood clotting with low platelets disorder called thrombosis with thrombocytopenia syndrome (TTS) associated with the vaccine, which began to surface in late February 2021.
“Although no evidence of increased overall risk of thrombosis or thrombosis with thrombocytopenia was noted among participants who received AZD1222 in this trial, thrombosis with thrombocytopenia syndrome (also known as vaccine-induced immune thrombotic thrombocytopenia) is rare,” the authors wrote.
“Independent safety reviews by regulatory authorities of available clinical and real-world evidence have concluded that the benefits of AZD1222 outweigh the potential risks, with protection from the serious consequences of COVID-19 increasing with age and SARS-CoV-2 infection rate.”
A committee responsible for preparing the European Medicines Agency’s opinions regarding human medicines said that it could not “identify particular risk factors that make TTS more likely” after analyzing all the available data related to the blood clotting disorder that occurred after receiving the AstraZeneca vaccine.
“The evidence did not allow EMA to identify particular risk factors that make TTS more likely. Although spontaneous reports when put in relation to the exposure have suggested that the risk may be higher in women and in younger adults, and lower after the second compared to the first dose, the limitations of the way the data is collected mean that none of these differences could be confirmed,” the committee said in a statement on Sept. 17.
The committee also said that the second dose may be continued to be given between the recommended four and 12 weeks after the first dose since there was “no evidence that delaying the second dose has any influence on the risk of TTS.”
In April, the EMA’s safety committee announced that blood clots with low platelets should be “listed as a very rare side effect” of the AstraZeneca COVID-19 vaccine and reminded health care professionals and individuals getting the vaccine to “remain aware of the possibility” of the severe clotting disorder within two weeks of vaccination.
Despite the reported cases of blood clots and low platelets, the EMA says the condition is “very rare, and the overall benefits of the vaccine in preventing COVID-19 outweigh the risks of side effects.”
A study funded by the drugmaker and released in July showed that its COVID-19 vaccine carried a small risk of blood clotting with low platelets after the first shot. The estimated rate of serious blood clotting disorder after the first injection was 8.1 per million in those who were vaccinated.
A spokesperson for AstraZeneca told The Epoch Times in an email that it will submit an application for approval from the Food and Drug Administration “later this year.”
“Currently, the situation with respect to the pandemic and availability of alternative vaccine supply in the US doesn’t really support an Emergency Use Approval. So, we believe that US approval will be via a BLA [biologics license application] which we expect to be submitted later this year,” the spokesperson said.
The AstraZeneca COVID-19 vaccine is only administered to adults 18 and older and is being used in countries including several European countries, Brazil, Australia (for people over 50), Canada (for those over 55), India, South Korea, and Papua New Guinea.