Should Bhutanese worry after Astra Zeneca withdraws its COVID-19 vaccine

The announcement by drug company Astra Zeneca that it is withdrawing its COVID-19 vaccine internationally has caused some flutter in Bhutan given that this was the same vaccine that was given as the first dose in Bhutan.

The particular reason for worry is after the company admitted in 100-million-pound lawsuit in UK that in very rare cases the vaccine can cause Thrombosis with Thrombocytopenia Syndrome or TTS.

According to the Melbourne Vaccine Education Center TTS is characterised by thrombosis formation (blood clots) combined with thrombocytopenia (low platelet count) with symptoms typically presenting in the 4-42 days after vaccination.

According to the Center for Diseases Control (CDC) TTS is classified into 2 tiers based on the location of thrombosis and severity of symptoms. 

Tier one which is more severe and with higher chancer of morbidity is when it occurs in uncommon areas like the brain and gut.

Tier 2 which is less severe and more common is when it occurs in the leg or lungs.

TTS seem to be caused by a rare immune reaction to the vaccine.

It is estimated that the risk of developing TTS after dose 1 of Vaxzevria (AstraZeneca) was approximately 2.6 per 100,000 persons, with those under 60 years experiencing more severe outcomes. The risk of developing TTS following dose 2 occurred at a much lower rate.

The Melbourne Vaccine Education Center said there currently no evidence that adenoviral vector vaccines increase the overall risk of developing other standalone thromboses (eg. other clotting disorders leading to deep vein thromboses, pulmonary emboli, myocardial infarction, stroke) beyond the baseline rate in the general population.

The fact that Astra Zeneca causes TTS is not new information as back in April 2021 itself the European Medicines Agency (EMA) pointed this out which the EMA said should be listed as very rare side effects of the COVID-19 Vaccine AstraZeneca.

In the case of Bhutan while it went for Astra Zeneca in the first round it largely went for  Moderna in the second, third and fourth rounds with Pfizer used for children above 5.

The former Health Minister Dasho Dechen Wangmo said there was no recorded TTS case in Bhutan as there was a Side Effects and Adverse Reaction Committee that followed patients.

Dasho said that the ministry was aware of the TTS risk and it must be understood that there can be no 100% safety in any vaccine which is why people are put under 30 minutes observation after any vaccine.

She said the vaccines serve a greater good.

The current Director of the National Medical Services (NMS) Dr Mimi Lhamu Mynak and former head of the Side Effects and Adverse Reaction Committee said there was not even a single case of TTS in Bhutan.

She said people were followed after the Astra Zeneca dose with follow up questions by calling them on the phone and even when the second dose in the form of Moderna was given people were asked if they had any TTS side effects and it was not seen.

Talking in The Guardian paper the chair of epidemiology at Deakin University in Australia, Prof Catherine Bennett, said the vaccine had played a pivotal part in the worldwide fight against the virus, particularly in the early days of the pandemic when limited vaccines were available.

“It has saved millions of lives and that should not be forgotten,” she said.

AstraZeneca said the decision was made because there is now a variety of newer vaccines available that have been adapted to target Covid-19 variants. This had led to a decline in demand for the AstraZeneca vaccine, which is no longer being manufactured or supplied.

Prof Catherine said, “It was a really important part of the initial global response. However, it targeted the initial ancestral variants. We’ve now moved into a vaccine chain where we have products available that are chasing the variants that are emerging.

In the case of Bhutan even if TTS happened given the global average of 2.6 per 100,000 people it may have happened to 10 people and this could range from the mild to the more serious.

Balance that against the 700 to 1,000 lives that could have been lost in Bhutan if the country was unvaccinated and a deadly variant like Delta had hit.

Bhutan kept out the deadlier Wuhan and Delta strains and vaccinated itself and opened itself to the milder Omicron strain.

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