The post-vaccination blood clotting and low blood platelet levels seen in a small number of people who received the Johnson & Johnson COVID-19 vaccine has not been seen in any Americans who got shots from Pfizer or Moderna, a U.S. official said Tuesday.
Dr. Peter Marks, director of the Food and Drug Administration's Center for Biologics Evaluation and Research, told reporters on a call that "at this time, we've not found any reports of cerebral venous sinus thrombosis combined with thrombocytopenia" among those who received a Pfizer or Moderna shot.
Moderna said that they performed an assessment of people who got their shot found no association with the blood clots.
"A comprehensive assessment of the totality of the available safety data for mRNA-1273 after over 64.5 million doses administered globally does not suggest an association with cerebral venous sinus thrombosis (CVST) or thrombotic events," the Massachusetts-based pharmaceutical and biotechnology company said in a statement.
The analyses were performed using data through March 22, with numbers derived from U.S. and European health agency websites.
Figures for other countries were inferred "based on distribution and the proportion of doses distributed" and administered, the company added.
Only three COVID-19 vaccines are currently authorized for use in the United States.
The third is a shot from Pfizer-BioNTech.
A Pfizer spokesperson told The Epoch Times via email that the company "conducted a comprehensive assessment of ongoing aggregate safety data" for its shot.
The assessment "provided no evidence to conclude that arterial or venous thromboembolic events, with or without thrombocytopenia, are a risk associated with the use of our COVID-19 vaccine," the spokesperson said in an emailed statement.
The analysis included a review of all post-vaccination adverse events through March 27.
Regulators authorized the Pfizer and Moderna vaccines in December 2020. So far, the vast majority of shots administered in the United States have been from one of the companies.
As of April 12, 97.9 million of the vaccines administered were from Pfizer, while 84.6 million were from Moderna.
Just 6.8 million, in comparison, were from Johnson & Johnson.
About 160,000 were not identified, according to Centers for Disease Control and Prevention data.
Both the Pfizer and Moderna shots are built on messenger RNA technology while Johnson & Johnson's uses an adenovirus vector, similar to one from the UK's AstraZeneca that is being considered for authorization by the Food and Drug Administration.
But a small number of people who got AstraZeneca's vaccine have also experienced blood clots.