Covishield and the Rare Case of TTS: Weighing Risks and Benefits

AstraZeneca’s Covishield vaccine, a mainstay in India’s fight against COVID-19, has been under scrutiny due to a rare side effect known as Thrombosis with Thrombocytopenia Syndrome (TTS). This news can be concerning, but it’s crucial to understand the risks involved and make informed decisions.

What is TTS?

TTS is a rare condition characterized by blood clots forming in unusual locations alongside a low platelet count (platelets are blood cells that help with clotting). Symptoms can include:

  • Severe headaches
  • Vision problems
  • Difficulty breathing
  • Chest pain
  • Leg swelling
  • Abdominal pain

These symptoms typically appear within 4 to 28 days of receiving the vaccine.

How Common is TTS with Covishield?

The good news is that TTS is an extremely rare side effect. The European Medicines Agency (EMA) [1] states that while a few cases have been reported, the benefits of the vaccine far outweigh the risks.

Here’s some perspective:

  • In the European Union, with hundreds of millions of Covishield doses administered, the EMA estimates a risk of 4 to 6 cases per million vaccinated people [2].
  • India, which has vaccinated a significant portion of its population with Covishield, has reported a similarly low incidence rate [3].

Why Did AstraZeneca Acknowledge the Risk?

AstraZeneca’s acknowledgement in court documents pertains to an ongoing legal case [4]. This doesn’t necessarily indicate a change in their position on the overall safety of the vaccine.

Should You Worry About Getting Covishield?

The overwhelming consensus from health authorities like the World Health Organization (WHO) [5] is that the benefits of Covishield in preventing severe COVID-19, hospitalization, and death far outweigh the very small risk of TTS. COVID-19 itself carries a much higher risk of blood clots than the vaccine.

Who is More Susceptible to TTS?

While anyone can develop TTS, certain factors may increase the risk:

  • Age: Reported cases have been more frequent in younger adults, particularly women under 60 [6].
  • Underlying health conditions: Individuals with conditions affecting blood clotting or platelets may be at slightly higher risk.

What if I’m Concerned About TTS?

If you have any concerns about TTS after receiving Covishield, be aware of the symptoms and seek immediate medical attention if you experience any of them. Early diagnosis and treatment can significantly improve outcomes.

Understanding Thrombosis Thrombocytopenia Syndrome (TTS)

TTS is a rare but serious blood clotting disorder that affects a small fraction of individuals who have received the AstraZeneca vaccine. It is characterized by the formation of blood clots in various parts of the body, along with a low count of blood cells called platelets, which are essential for clotting.

The Risk-Benefit Analysis

While the occurrence of TTS is concerning, it’s crucial to note that the overall risk of developing this condition after receiving the AstraZeneca vaccine is extremely low. According to experts, the benefits of the vaccine in preventing severe Covid-19 illness and death far outweigh the risks of developing TTS.

AstraZeneca’s Response

AstraZeneca has faced legal challenges related to TTS, with claimants alleging that the vaccine caused death or serious injury. The company, while contesting these claims, has accepted in court documents that its vaccine can, in very rare cases, lead to TTS.

Expert Opinion

Infectious disease experts emphasize the rarity of TTS and urge the public not to panic. They highlight the challenges of differentiating between complications caused by the vaccine and those associated with Covid-19 itself.

Here are some resources for further information:

Vaccination: The Best Defense Against COVID-19

Despite the rare possibility of TTS, Covishield remains a highly effective and safe vaccine. Vaccination is the single most powerful tool we have to control the COVID-19 pandemic and protect ourselves and our loved ones.

Additional Considerations

  • Talk to your doctor: If you have any underlying health conditions or specific concerns, discuss them with your doctor before getting vaccinated. They can assess your individual risk factors and advise you accordingly.
  • Benefits outweigh risks: The overwhelming scientific evidence confirms that the benefits of Covishield in preventing severe COVID-19 far outweigh the extremely low risk of TTS.
  • Stay informed: Reliable sources like the WHO and CDC offer the latest information on COVID-19 vaccines and potential side effects.


The acknowledgement of TTS as a rare side effect of Covishield shouldn’t overshadow the vaccine’s proven effectiveness in preventing serious illness and death from COVID-19. Weighing the risks and benefits, vaccination remains the best course of action for most people. By staying informed, talking to your doctor, and getting vaccinated, we can collectively move towards a safer and healthier future.