Dr Krishna Reddy Nallamalla

The world has witnessed a great scientific feat in developing the Covid vaccines within just a year of the onset of the pandemic. Given the crisis, many regulators have issued emergency use authorization (EUA) for these vaccines, with a stipulation to put in place a robust post-market surveillance system. As a part of this stipulation, companies are required to track every vaccinated person for any adverse events as per prior definitions. An independent body will adjudicate these adverse events as being either or not related to the vaccine.

As part of greater transparency in the regulatory process, the information on various adverse events is publicly displayed or disclosed according to the situation. Current day digital technologies make the information available to everyone instantaneously. Everyone is free to give their opinion, unmindful of its impact on lay people. The result is the prevalent plague of information deluge (named as ‘infodemic’) that is bringing more havoc than the pandemic itself. It is one of the key reasons behind vaccine hesitancy among people.

Countries in European Union (EU) started reporting rare cases of an unusual blood clotting disorder in people recently vaccinated with the Oxford-Astra-Zeneca Covid vaccine. Many countries in the EU temporarily halted the administration of the vaccine until further investigation by the European Medical Agency (EMA). After thorough investigation, the EMA did admit a possible causal relation between abnormal blood clotting and the vaccine. However, it recommended the continuation of the vaccine given the greater benefit of getting vaccinated than the rare risk of the clotting disorder. UK reported 30 cases out of 18 million doses administered, i.e., less than 2 cases per million doses. Since the risk of Covid is less in people younger than 45 years of age, many countries are trying to avoid the said vaccine in younger populations.

The most prestigious medical journal, the New England Journal of Medicine (NEJM) published two articles in its latest issue, one from Germany (that studied 11 cases) and the other from Denmark (5 cases) on patients presenting with the rare clotting disorder, following the vaccination. All individuals were young (between 30 to 45 years of age). Thirteen of 15 reported cases were females. All presented clots in various vascular structures (predominantly veins in brain and abdomen) along with low platelet counts. Antibodies that bind platelets were detected in all cases. All cases were very similar to a well-known entity in clinical practice – heparin induced thrombocytopenia (HIT) – that happens in rare cases in patients after administration of the heparin injection that is generally used to prevent or treat clots. However, there was no history of heparin administration in these cases prior to presentation. The authors have termed the new disorder as Vaccine Induced Thrombocytopenia (VIT) to differentiate it from HIT. 

It is still not clear why some young people develop this disorder following a specific vaccine. Similar rare cases have also been reported with theJ&J vaccine. Both the vaccines use adenovirus as the vector. The Russian vaccine, Sputnik V and the Chinese vaccine also use the adenovirus vector. However, there are no reports of similar cases from these vaccines. Given the lack of data transparency with these two vaccines, it is not clear whether these vaccines also have similar adverse events. Researchers are vehemently investigating the exact cause for this rare complication.

While we await further scientific data, it is important for people to understand the issue in the right perspective. Every drug, device, and vaccine used in clinical medicine has adverse effects. All these adverse effects are detailed in product labels and information sheets. These products are approved by regulatory bodies based on the risk-to-benefit ratio, i.e., the benefit of taking the product versus the risk of taking it. The benefit has to clearly exceed the risk manifold. In this specific instance, the risk of not getting vaccinated outweighs the risk of developing this rare disorder. Supposing a 1000 people out of one million (0.1%) or one in 1000 test positive during a surge, 10 to 30 people may die due to serious illness (assuming a case fatality rate of 1 to 3% depending on the demographics). If the same one million people were to get Astra-Zeneca vaccine, and two were to develop the clotting disorder (as per the prevalence reported from UK) and one were to die of the disorder, the benefit outweighs the risk by 10 to 30 times. Supposing younger people have a 0.1% case fatality rate, the risk is similar or slightly higher compared to the benefit. That explains why some countries are adopting the stance of restricting the use this vaccine in younger people.

Given the complexity of arriving at a practical decision, people should wait for appropriate international (WHO) and national bodies (Ministry of Health) to come up with guidance on use or non-use before jumping to conclusions based on ill-informed opinions. The media should be highly responsible while reporting these issues. Just as every profession has professional ethics to adhere to, media too should be bound by the ethic to be responsible to the society. Even individual experts, their reputation notwithstanding, have to be very careful in the words they use in public discourse, during debates, and interviews. It is the primal response of people to respond to a threat – real or perceived – by avoidance (evolutionary flight response). Perceived risk should not override the real benefit.

Dr Krishna Reddy Nallamalla
President, InOrder
Country Director, ACCESS Health International.