The Cambridge, England based pharmaceutical company, AstraZeneca has had, like its Covid vaccine cohort, Johnson & Johnson, a very bad month. Following dozens of reports of blood clots and at least 18 deaths believed to be the result of an adverse reaction to the AstraZeneca vaccine, the European Medicines Agency (EMA) acknowledged the blood clot risk. Although the EMA stopped short of recommending halting the vaccine, several countries have done just that, including Italy, Sweden, France, Germany, Norway, Denmark and the Netherlands. 

Consequently, the chances of the company receiving emergency use authorization for its vaccine by the US FDA, should it seek to do so (as of this writing, the company has not done so), are slim. 

Another setback for AstraZeneca, albeit less publicized, is the news earlier this week that its diabetes drug Farxiga was not successful in treating COVID patients at risk of severe complications, reports MedicalXpress.com. 

AstraZeneca said, per MedicalXpress.com, that its trial “assessing the potential of Farxiga to treat patients hospitalised with COVID-19 who are at risk of developing serious complications… did not achieve statistical significance”.  

Some people who contracted Covid developed diabetes even though they had no previous history of blood sugar problems. It is not clear if Farxiga would have been used for this subset of Covid patients. 

As for AstraZeneca’s Covid vaccine, it is authorized by the World Health Organization and the European Union. Produced in conjunction with the pharmaceutical company’s academic research partners at Oxford University, the vaccine was the hope for much of the world to return to normalcy. Less expensive to produce and easier to store and distribute, the vaccine was supposed to provide protection to dozens of developing countries who don’t have the resources to purchase the more expensive Pfizer and Moderna vaccines. 

Time Magazine reports that two new studies provide a detailed explanation of how AstraZeneca’s vaccine may cause blood clots. 

Vaccine-induced immune thrombotic thrombocytopenia

Although reports of fatal or injurious blood clots are said to be extremely rare—as of last week, in the UK, there were 7 deaths blamed on blood clots that were triggered by the AstraZeneca vaccine—public health officials around the world are taking a cautious approach. Time Magazine reports that in some people who received the AstraZeneca jab, there were higher levels of antibodies directed against a cluster of immune-related cells that the body might form in response to the vaccine.

These clusters include blood-clotting platelets. Blood clots are the body’s natural response to cuts and injuries. However, when antibodies stick to the platelets, dangerous clots can form in the cardiovascular system. The researchers describe the condition as “vaccine-induced immune thrombotic thrombocytopenia.”

Many of the cases involved young recipients of the AstraZeneca jab. In response to the risk of blood clots, the EMA issued a recommendation that those under 30 get another vaccine, if possible. Despite the risk of blood clots, the European agency recently concluded that the benefits of vaccination in protecting against COVID-19 outweighed the small risk posed by clotting.

However, the two studies referenced in the Time Magazine article, both published in the New England Journal of Medicine, “will reignite questions about the safety of the vaccine, and potentially lead to new policies or even stricter monitoring of people who receive it,” writes TIME’s Alice Park. 

How Does The AstraZeneca Vaccine Work?

It uses so-called vector-based technology, which uses non-replicating viral vectors. Viral vectors deliver genetic material into cells. The antigen (the material that fights the virus) is also injected into the nuclei of cells.

Vector-based technology, says the TIME Magazine report, is only approved for use in a rabies vaccine for animals. To date, COVID-19 is the only human disease that vector vaccines are approved to prevent. 

Park interviewed a vaccine expert who did not wish to be identified. The expert said of the studies on the AstraZeneca vaccine, “These results cast a shadow on this vaccine and now other vaccines—the Russian vaccine, and Johnson & Johnson—relying on this technology.” 

The expert added, “Now all of these will be looked at with higher scrutiny, and they should be.” 

Like AstraZeneca’s vaccine, Johnson & Johnson’s single dose vaccine has been associated with blood clots (at least one fatal) in rare cases. 

How Long Does It Take For Blood Clots From The AstraZeneca Vaccine To Develop?

In one of the studies published in NEJM, the case history of 28 people who developed blood clots was reviewed. All 28 developed different types of clots five to 16 days after vaccination. Six of the 28 died from their clotting complications, reports TIME. The other NEJM examined five Norweigan health care workers, all of whom developed blood clots seven to 10 days after receiving the AstraZeneca vaccine. Three of the health care workers died. 

The effect of the blood clotting from the AstraZeneca vaccine is similar to rare side effects of the blood-thinning medication, heparin (Warfarin). 

Although reports of the blood clots are rare, “it’s tough to see healthy people in their 30s and 40s dying [after receiving] the vaccine when they probably would have been fine with a COVID-19 infection,” said a co-author of the Norweigan study. 

Read the full article on Time.com here.