The European Medicines Agency (EMA) announced yesterday that the overall benefits of the AstraZeneca and Johnson & Johnson vaccines against Covid-19 outweigh the risks, even when they added warning labels to both vaccines for extremely rare but potentially fatal deaths.
J&J said yesterday, April 20, that it would continue delivering its vaccine to Europe, in accordance with Coreper's instructions. U.S. officials continue to look into the eight reported U.S. cases of rare thrombosis associated with low platelet counts after the vaccine was given.
The British health regulator has recommended that people under the age of 30 receive a different coronavirus vaccine, if possible, instead of the AstraZeneca vaccine, while some other European countries give the vaccine only to the elderly.
Amid concerns that these rare cases of side effects could undermine confidence in the global coronavirus vaccination campaign, vaccine and immunology experts say the risk of thrombosis for both vaccines remains extremely low in both vaccines. deaths and serious illnesses from Covid-19.
Here is what has become known so far:
What has happened;
Reports of AstraZeneca and J&J vaccines include extremely rare cases of thrombosis, mainly a type of thrombosis called cerebral venous thrombosis (CVST) observed in combination with low platelet counts, called thrombocytopenia.
The European regulator also reported that most blood clots appeared in the brain and abdomen, as with the AstraZeneca vaccine, Vaxzevria, which is also being studied for similar blood clotting problems.
The US Centers for Disease Control and Prevention (CDC) has scheduled a meeting for April 23 to consider a link between thrombosis and the J&J vaccine, and possibly a decision. US services, like European services, describe these cases of thrombosis associated with vaccines as extremely rare.
According to the European Medicines Agency, there have been 325 cases of rare thrombosis associated with low platelet counts worldwide following vaccination with Covid-19, at a time when more than 928.000.000 million doses of vaccine have been administered worldwide, according to a New York Times count.
In particular, 287 cases have been reported related to the AstraZeneca vaccine, 8 to that of Johnson & Johnson, 25 to Pfizer and 5 to Moderna, said Peter Arlett, head of data analysis at EMA.
Of these, 142 cases have been reported in the European Economic Area (EEA) out of almost 30.000.000 doses of the Astrazeneca vaccine administered in the last three months in Britain and the EEA.
The J&J vaccine review by the EMA covered eight cases of people receiving the vaccine in the United States. All cases were under 60 years of age and most involved women who developed symptoms within three weeks of receiving the vaccine.
These 8 cases occurred while 8.000.000 doses of the J&J vaccine have been administered in the US to date.
The EMA said earlier this month that of the cases it had examined in depth, 18 had died.
What do pharmaceutical companies say?
J&J said a new label on its vaccine packaging would include a warning about the risk of a rare side effect and instructions on how to identify and treat it. The company announced yesterday, April 20, that it will resume cargo shipments to the European Union, Norway and Iceland and is working to restart clinical trials.
AstraZeneca, which is still distributing its vaccines, said it was "working to understand individual cases and possible mechanisms that could explain these extremely rare cases".
What do regulators say?
The US regulator has suspended the use of the J&J monosodium vaccine "as a precautionary measure" to ensure that healthcare providers are fully aware of potential side effects and can plan for "proper identification and management".
In part, the suspension has been used to ensure that physicians are aware of treatment options, including medications that should be given to help treat thrombosis, without further endangering patients' lives.
The UK regulator for medicines and healthcare products, meanwhile, has issued its recommendation for an alternative vaccine to AstraZeneca for people under the age of 30, after examining 79 cases of rare thrombosis associated with low platelet counts. , with 19 deaths - 13 women and six men.
Eleven of the deaths involved people under the age of 50 and three under the age of 30.
What treatment is recommended?
In the United States, health officials have reported that the treatment of thrombosis that may be related to the J&J vaccine is different from what may be standard in such cases.
"Usually, an anticoagulant drug called heparin is used to treat blood clots," they say. "In this context, heparin administration can be dangerous and alternative therapies must be administered," they added.
The EMA has so far stated that heparin should not be given until a diagnosis of a similar condition - called heparin-induced thrombocytopenia (HIT) - is ruled out. Alternative anticoagulants may be used, such as fondaparinux or argatroban.
But even when HIT is ruled out, the EMA notes that "it is not yet clear whether patients with post-vaccination thrombosis syndrome could be treated with heparin, mainly because there is little evidence."
German doctors and scientists investigating thrombosis associated with the AstraZeneca vaccine have also said that the issue of heparin remains "unclear" and have recommended that professional doctors administer intravenous immunoglobulin along with anticoagulants.
How did the health regulators come to their decisions?
For the AstraZeneca vaccine, the EMA said in March that, on average, only 1,35 cases of CVST could normally be expected in the under-50 age group within 14 days of receiving the vaccine.
By comparison, four in 10.000 women would develop blood clots after taking birth control pills.
British officials advising people under the age of 30 to receive an alternative vaccine have drawn statistics from the Wheaton Center at the University of Cambridge.
According to the Center, the risk of serious harm from vaccination decreases as the age of the vaccinated increases and the number of admissions to intensive care units decreases rapidly thanks to vaccinations, enhancing the benefit / risk ratio of the AstraZeneca vaccine.
The Center concluded that just 0,4 people for every 100.000 in the 50-59 age group will suffer vaccine-related injuries, while 95.6 ICU admissions per 100.000 people will be avoided.
What is the EU doing now?
The EMA, which says the benefits of using AstraZeneca and J&J vaccines continue to outweigh the risks, said unusual low-platelet blood clots should be reported as very rare side effects and has left countries to decide how to proceed.
Their decisions may vary from country to country, the EMA said, depending on factors such as infection rates and whether there are vaccine alternatives. Denmark, for example, has chosen to suspend the use of the AstraZeneca vaccine and is still considering plans for the J&J vaccine.
Is there a theory for the cause of thrombosis?
Among the possible causes being investigated is that the vaccine activates an unusual antibody in rare cases. So far, risk factors such as age or gender have not been segregated.
While most of the cases reported so far involving the AstraZeneca vaccine have been recorded in women, scientists in Germany say this may be misleading, as women make up the largest population group of people who have received the vaccine.
Health regulators and scientists are also investigating whether the problem of thrombosis can affect the entire class of so-called viral vaccine-based vaccines, which the EMA said was possible, noting differences between the two vaccines.
German scientists at the University of Greifswald have concluded that the extremely rare cases of low platelet thrombosis - something they call "VITT" (immunological thrombocytopenia after vaccination) - are activated in AstraZeneca vaccine.
Separately, Norwegian scientists came to similar conclusions in their own research.
J&J has agreed to work with scientists at the University of Greifswald to investigate the possible causes.