AstraZeneca’s COVID-19 shot and blood clots

Amid blood clot concerns following the inoculation with the vaccine developed by AstraZeneca (NASDAQ:AZN), two groups of medical experts from Norway and Germany say they have found the mechanism and a possible treatment for the rare events, the WSJ reports.

Several isolated cases of cerebral venous sinus thrombosis following the vaccination caused many countries across Europe to pause vaccinations with Astra’s COVID-19 jab leading the European Medicines Agency (“EMA”) to issue a statement backing its use.

Subsequently, countries such as Germany, France, and Italy resumed inoculations while Norway, Denmark, and Sweden continued to suspend the rollout subject to a further review of the EMA decision.

After investigating the cases in Norway, Pål André Holme, a professor of hematology and chief physician of the Oslo University Hospital said his team has identified an antibody created by the vaccine as the trigger for the adverse reaction.

A team of German researchers led by Andreas Greinacher, professor of transfusion medicine at the Greifswald University Clinic said they have independently reached a similar conclusion.

Noting that findings are no reason for people to fear to get Astra’s COVID-19 shot, Prof. Greinacher added, “very, very few people will develop this complication. but if it happens, we now know how to treat the patients.”

After a quick diagnosis, any midsize hospital could treat the condition, he said, and after a review of Prof. Greinacher’s findings, the German Society for Thrombosis and Hemostasis Research has issued guidelines on how to diagnose and treat the condition.

Neither the Norwegian nor the German studies were peer-reviewed, and within the next few days, Prof. Greinacher expects to submit his work for publication in the British medical journal The Lancet.

AstraZeneca has declined to comment and after a review of cases in Norway and Germany, the EMA has reiterated the vaccine’s favorable risk-benefit profile. The German government is assessing the findings and has not changed its decision to resume the vaccine rollout.Meanwhile, ahead of a possible decision by the FDA on emergency use approval for Astra’s COVID-19 shot, the U.S. government is sending millions of the vaccine doses to its neighbors.

The WHO Strategic Advisory Group of Experts on Immunization (SAGE) has issued interim recommendations for use of the Oxford/AstraZeneca COVID-19 vaccine (AZD1222).

Vaccination is recommended for persons with comorbidities that have been identified as increasing the risk of severe COVID-19, including obesity, cardiovascular disease, respiratory disease and diabetes.Although further studies are required for persons living with HIV or auto-immune conditions or who are immunocompromised, people in this category who are part of a group recommended for vaccination may be vaccinated after receiving information and counseling.Vaccination can be offered to people who have had COVID-19 in the past. But individuals may wish to defer their own COVID-19 vaccination for up to six months from the time of SARS-CoV-2 infection, to allow others who may need the vaccine more urgently to go first.

Vaccination can be offered to breastfeeding women if they are part of a group prioritized for vaccination. WHO does not recommend discontinuation of breastfeeding after vaccination.While pregnancy puts women at higher risk of severe COVID-19, very little data are available to assess vaccine safety in pregnancy.Pregnant women may receive the vaccine if the benefit of vaccinating a pregnant woman outweighs the potential vaccine risks.For this reason, pregnant women at high risk of exposure to SARS-CoV-2 (e.g. health workers) or who have comorbidities which add to their risk of severe disease, may be vaccinated in consultation with their health care provider.

People with a history of severe allergic reaction to any component of the vaccine should not take it.The vaccine is not recommended for persons younger than 18 years of age pending the results of further studies.The recommended dosage is two doses given intramuscularly (0.5ml each) with an interval of 8 to 12 weeks.Additional research is needed to understand longer-term potential protection after a single dose. 

Two versions of the vaccine – produced by AstraZeneca-SKBio (Republic of Korea) and the Serum Institute of India – have been listed for emergency use by WHO. When the vaccine underwent SAGE consideration, it had undergone review by the European Medicines Agency (EMA).The EMA has thoroughly assessed the data on the quality, safety and efficacy of the vaccine and has recommended granting a conditional marketing authorization for people aged 18 and above.

The Global Advisory Committee on Vaccine Safety, a group of experts that provides independent and authoritative guidance to the WHO on the topic of safe vaccine use, receives and assesses reports of suspected safety events of potentially international impact.The AZD1222 vaccine against COVID-19 has an efficacy of 63.09% against symptomatic SARS-CoV-2 infection.Longer dose intervals within the 8 to 12 weeks range are associated with greater vaccine efficacy.

SAGE has reviewed all available data on the performance of the vaccine in the settings of variants of concern. SAGE currently recommends the use of AZD1222 vaccine according to the WHO Prioritization Roadmap, even if virus variants are present in a country. Countries should assess the risks and benefits taking into consideration their epidemiological situation.Preliminary findings highlight the urgent need for a coordinated approach for surveillance and evaluation of variants and their potential impact on vaccine effectiveness. As new data become available, WHO will update recommendations accordingly.No substantive data are available related to impact of AZD1222 on transmission or viral shedding.

Bangladesh has to take cautious steps towards using the vaccine. In the meantime, we must maintain and strengthen public health measures that work: masking, physical distancing, hand washing, respiratory and cough hygiene, avoiding crowds, and ensuring good ventilation. 

* Writer, freelance journalist