It has been reported that Johnson & Johnson contacted Pfizer, Moderna, and AstraZeneca about investigating the clots and to “speak with one voice about safety.” However, both Pfizer and Modera declined, indicating that their vaccines were not associated with blood clots.
It has been reported that Johnson & Johnson contacted Pfizer, Moderna, and AstraZeneca about investigating the clots and to “speak with one voice about safety.” However, both Pfizer and Modera declined, indicating that their vaccines were not associated with blood clots.
The two companies didn’t see a need to duplicate regulators’ investigations, and they are already studying the blood clotting. Some of the sources said there were concerns Pfizer and Moderna might be linked to the blood clotting issue.
So far, both the AstraZeneca-Oxford and Johnson & Johnson COVID-19 vaccines have been associated with very rare but potentially life-threatening blood clots. The actual cause of the clotting has not been determined.
In addition, the blood associated with each vaccine appears to be different from the other. The U.S. has paused the distribution of the J&J vaccine. The AstraZeneca-Oxford vaccine has been halted in about 20 European countries but has yet to be authorized in the U.S.
In the case of the J&J vaccine, the blood clots are cerebral venous sinus thrombosis (CVST), which were observed in combination with low levels of blood platelets (thrombocytopenia). The reported cases occurred in women between 18 and 48, with symptoms appearing six to 13 days after the shot.
In the AstraZeneca-Oxford vaccine, the clots are deep vein thrombosis (DVT) and pulmonary embolism. It is not clear if the vaccines are causing the clots or if the mechanisms behind the clotting in the two vaccines, if it is there at all, are the same.
AstraZeneca agreed to work with Johnson & Johnson. WSJ points out that rival drugmakers have partnered and shared information far more than usual during the pandemic.
A J&J spokesman said the company believed a collaborative effort could help answer questions about the clots and patient safety. It is also working with regulators in the U.S. and Europe on specific blood clotting events. All companies indicate that the benefits of the vaccines, even AstraZeneca and Johnson & Johnson’s, outweigh the risks.
In the J&J shot, the risk of blood clots is about 1 in 1 million. The risk of clots associated with the AstraZeneca vaccine appears to be about 5 in 1 million. According to a study by Oxford University, the risk for the Pfizer-BioNTech and Moderna vaccines appears to be somewhere in the 4 in 1 million range. However, about 16% of COVID-19 patients are at risk of severe blood clots, which is about 10 times higher than the mRNA vaccines’ risk from Pfizer-BioNTech and Moderna.
“COVID-19 markedly increases the risk of CVT, adding to the list of blood clotting problems this infection causes,” said Paul Harrison, professor of psychiatry and head of the Translational Neurobiology Group at the University of Oxford. “The COVID-19 risk is higher than we see with the current vaccines, even for those under 30, something that should be taken into account when considering the balances between risks and benefits for vaccination.”
While the Moderna and Pfizer-BioNTech mRNA vaccines use lipid nanoparticles to deliver mRNA coding for the COVID-19 virus’s spike protein, both the AstraZeneca-Oxford and J&J vaccines use common cold adenoviruses as vectors, a human adenovirus for the J&J vaccine, a chimpanzee adenovirus for the AstraZeneca-Oxford vaccine.
There has been some debate on whether this “abundance of caution” over the clotting risks is actually an “over-abundance of caution.” The chances of blood clots are statistically extremely rare.
“It might turn people off from getting vaccines, but the flip side of that is these are brand-new vaccines,” said Kawsar Talaat, assistant professor in the department of international health at the Johns Hopkins Bloomberg School of Public Health. “When we see a safety signal arise, we stop and examine it, and decide how best to move forward in order to maximize people getting vaccinated but also protecting people from adverse events.”
