Doctors with long experience in diagnosing very sick patients describe it as one of the rarest and most confusing scenarios they have seen: A patient arrives in a hospital emergency department with one or more life-threatening blood clots in the brain, lungs, bones or abdomen despite low levels of platelets, the cells are the raw material for blood clots.
It is the medical equivalent of a traffic light flashing red and green at the same time.
‘Whoa!’ said Dr. Gregory Poland, intern at Mayo Clinic. “It’s everyone’s attention.”
The condition is called autoimmune thrombocytopenia. It occurs when the immune system ignites incorrectly and generates antibodies against the patient’s platelets – sometimes spontaneously, but mostly in patients treated with the blood thinner heparin.
Poland has said it has seen it once, maybe twice, in a decade-long career studying immune responses to diseases and vaccines.
But within a few weeks, it was reported in six patients in the United States.
All were women. All were between 18 and 48 years old. And everyone received Johnson and Johnson’s COVID-19 vaccine with one shot between six and 13 days before they got one of the many signs of a blood clot: sudden shortness of breath, a painful, swollen leg, an attack of extreme and unusual abdominal pain, or severe, rapid onset headache or neurological symptoms such as dull face, disorientation, or muscle weakness.
The six reports appear after 6.8 million doses of J&J vaccine went into Americans’ arms. Although extremely rare – apparently less than one in a million – one American patient died and a second was left in critical condition.
And on Tuesday, they urged the U.S. Centers for Disease Control and Prevention and the Food and Drug Administration to recommend a ‘break’ in the administration of Johnson & Johnson’s COVID-19 vaccine.
During the break, independent and federal experts will study whether the country’s most recent addition to its vaccine arsenal is the cause of the coagulation disorders, and whether the vaccine should still be recommended for all adults over 18 years of age. The CDC will meet. its advisory committee on immunization practices on Wednesday to consider the questions.
The break comes on the heels of a European Union decision to temporarily suspend the administration of a similar COVID-19 vaccine made by AstraZeneca.
After administering 20.2 million doses of the two-dose vaccine, European regulators collected approximately 44 reports of immune thrombotic thrombocytopenia, or VITT. It is suspected that it was not caused by heparin or a random autoimmune reaction, but by the AstraZeneca vaccine.
Most of the cases were seen in patients younger than 40, and 4 out of 5 were reported in women.
In a study among 11 patients in Germany and Austria who suffered VITT, six died. All showed high levels of antiplatelet factor 4 antibodies, which are involved in autoimmune thrombocytopenia.
The authors of the report speculated that free DNA in the AstraZeneca vaccine could possibly cause these abnormal antibodies.
Although the vaccines made by AstraZeneca and Johnson & Johnson differ in many ways, they are linked in one important respect. Both use an adenovirus – a common cold germ that is deprived of its ability to suck – to give the immune system the necessary solution to recognize and attack the SARS-CoV-2 virus.
The AstraZeneca vaccine uses an adenovirus derived from chimpanzees, while Johnson & Johnson’s vaccine uses a human adenovirus.
‘It is already clear to us that what we see with [the Johnson & Johnson] vaccines are very similar to what we see with the AstraZeneca vaccine, ”said dr. Peter Marks, the FDA’s head of drug evaluation, said.
Regulators, he added, would look at “the total evidence” to determine if the rare immune response was linked to the two vaccines’ common vectors.
AstraZeneca has not yet sought the FDA’s emergency use permit for its COVID-19 vaccine, although the company said it plans to do so soon.
No cases of blood clots in the presence of a low platelet count were reported among patients receiving the COVID-19 vaccines made by Pfizer-BioNTech or Moderna, both using mRNA technology instead of adenoviruses.
The warnings from the FDA and CDC also warned doctors about the symptoms and proper treatment of blood clotting complications in patients who recently had a dose of Johnson & Johnson vaccine.
“You get these blood clots and doctors will usually come to heparin, and it’s a no-no in this disorder,” said dr. Jeffrey Weitz, president of the International Society of Thrombosis and Haemostasis, and a professor of medicine at McMaster University in Canada said. Instead, he said, doctors are urged to treat such coagulation disorders with intravenous immunoglobulin.
The cause of these rare blood clots is unknown. But dr. Hanny Al-Samkari, a hematologist and researcher at Massachusetts General Hospital and Harvard Medical School, said that the immune system can form antibodies against a component of the vaccines against adenovirus, which then cross-react with platelets and activate them, create “lumps where it should not be.”
Women’s stronger immune systems can cause these reactions in them more than in men, Al-Samkari said.
And while it is far too early to draw a link to oral contraceptives, Poland says researchers are also likely to explore the possibility that women taking pills – which may increase the risk of getting blood clots – may be advised to get rid of them. of the enterovirus vaccines.
In a statement released Tuesday, Johnson and Johnson said they were “aware of an extremely rare disorder” involving people with blood clots in combination with low platelets in a small number of individuals taking the COVID-19. vaccine received.
The company said it was reviewing matters with both US and European regulators and “decided to proactively delay the launch of our vaccine in Europe.”
The reports of the blood clot are likely to deepen the concerns of about 30% of Americans who are reluctant to be vaccinated or have said they will not get a COVID shot. But federal officials said Tuesday that the “break” is necessary and that the government’s transparency should reassure Americans.
Poland, who has served as a consultant to Johnson & Johnson, AstraZeneca and other vaccine manufacturers, added that the speed with which government watchdogs detect and respond to a weak signal of potential problems should inspire confidence.
“Even in the midst of all this fog, our safety signals picked it up,” he said. ‘In a pea mist you see a light: is it a ship? Is it a lighthouse, is it the coast? We can not yet know. These things are so hard to tease, and they’re so rare. This is a logical reason for a break. ”