US pauses use of Johnson & Johnson vaccine after “rare and severe” blood clots

Health officials in the United States have decided to pause administration of the Johnson & Johnson Covid-19 vaccine while they investigate a number of cases of “rare and severe” blood clots. According to a CNN report, a 45 year old woman has died and another patient is in critical condition. In total, there were 6 blood clot incidents, out of more than 6.8 million vaccine doses administered. All of the cases involved female patients between the ages of 18 and 48, with symptoms developing between 6 to 13 days after inoculation.

Speaking to CNN, Dr Carlos del Rio from Emory University School of Medicine says that such side-effects are extremely rare, pointing out that they’re more likely to be observed outside clinical trials, due to the larger number of people involved.

“It’s a very rare event. You’re talking about 1 per million, and when you give millions of doses of vaccines, you will see events like this that you couldn’t see in the clinical trial just because you didn’t have millions of people enrolled.”

He adds that blood clotting may be occurring for the same reason seen with the AstraZeneca vaccine, given that both jabs are adenovirus vector vaccines. The other vaccines in use in the US – Pfizer and Moderna – are mRNA vaccines.

Peter Marks from the US Food and Drug Administration agrees that there appear to be similarities between the incidents of blood clots reported with both the Johnson & Johnson and AstraZeneca vaccines.

“The AstraZeneca is a chimpanzee adenoviral vector vaccine. The Janssen is a human adenoviral vector vaccine. We can’t make some broad statement yet, but obviously they are from the same general class of viral vectors. We don’t have a definitive cause, but the probable cause that we believe may be involved here – that we can speculate – is a similar mechanism that may be going on with the other adenoviral vector vaccine. That is that this is an immune response that occurs very, very rarely after some people receive the vaccine and that immune response leads to activation of the platelets and these extremely rare blood clots.”

Janssen is the vaccine arm of Johnson & Johnson. Yesterday, the manufacturer issued a statement confirming a decision to delay the European rollout of its Covid-19 vaccine. The statement goes on to say that anyone who has already received the jab and experiences a severe headache, abdominal pain, leg pain or shortness of breath within 3 weeks of being inoculated should see a doctor. However, it adds that such side effects are extremely rare.

Last month, the Johnson & Johnson single-dose vaccine became the third jab to be approved for emergency use in Thailand.

SOURCE: CNN