Covishield Side Effects and Safety Measures: The Rare Risk of TTS Explained:


In a significant development, AstraZeneca has acknowledged for the first time that its Covishield vaccine, developed in partnership with the University of Oxford, can potentially cause rare side effects. Among these is Thrombosis with Thrombocytopenia Syndrome (TTS), a serious condition characterized by the formation of blood clots and a low platelet count.

This admission comes amidst ongoing legal challenges, with the pharmaceutical giant facing a class action lawsuit alleging that the vaccine led to death and severe injuries in some individuals. Despite these concerns, the World Health Organization continues to endorse Covishield as safe and effective for all individuals aged 18 and above, noting that the occurrence of TTS is "very rare." This revelation highlights the complex balance between vaccine efficacy and the risks of rare adverse effects in the global fight against COVID-19.

covishield side effects

About the vaccine

The Covishield Vaccine was a crucial tool in the fight against the coronavirus disease 2019 (COVID-19), which is caused by the highly infectious coronavirus SARS-CoV2. This vaccine was specifically approved for active immunization in individuals who are 18 years and older. The main goal of the vaccine was to prevent COVID-19, helping to curb the spread of this disease.

Developed in collaboration between Oxford University in the UK  and the leading biopharmaceutical company AstraZeneca, the vaccine has undergone extensive clinical trials. These trials were successfully carried out in multiple countries including South Africa, Brazil, and the UK. Additionally, bridging studies were conducted in the Indian population, which played a significant role in the approval of the vaccine by the national regulatory authority.

Covishield is administered through an injection into the muscle of the upper arm. The complete vaccination process requires two doses, which should be administered 4 to 6 weeks apart.

Side effects of Covishield:

Covishield vaccine is generally well-tolerated, but like all vaccinations, it can cause side effects in some individuals. These effects can range from mild to severe, although severe reactions are less common.

Common side effects include:

  • Injection site reactions: These are the most frequent and may include pain, swelling, and redness at the injection site.
  • Headache: A prevalent side effect that usually resolves within a few days.
  • Nausea and Vomiting: These symptoms can occur shortly after the vaccination and are typically temporary.
  • Muscle and Joint Pain: Recipients may experience pain in muscles and joints, which generally diminishes after a few days.
  • Fever, Chills, and Flu-like Symptoms: Many individuals report a mild fever, chills, or an overall flu-like feeling post-vaccination, indicating the body's immune response.
  • Fatigue: A feeling of tiredness or exhaustion is common but usually short-lived.

Severe side effects include:

  • Myocarditis: In rare cases, the vaccine can lead to myocarditis, an inflammation of the heart muscle, which might present symptoms related to heart failure.
  • Arrhythmias: There is a slight increase in the risk of developing abnormal heart rhythms, either as a slowdown or a rapid, irregular heartbeat.
  • Thrombosis with Thrombocytopenia Syndrome (TTS): A very rare condition where individuals develop blood clots along with low levels of blood platelets, which could be serious.

It is important to monitor for any side effects following vaccination and consult a healthcare provider if any severe or persistent symptoms occur.

Understanding the rare side effect of Covishield: TTS

Thrombosis with Thrombocytopenia Syndrome (TTS) is an infrequent but serious condition that has been observed in individuals who have received adenoviral vector COVID-19 vaccines, including Covishield. This section aims to provide a detailed understanding of TTS, its mechanisms, classification, and symptoms.

Mechanism of TTS

  • TTS occurs when blood clots form in unusual parts of the body such as the brain or gut, coupled with a drop in platelet counts. Platelets are crucial for blood clotting, and a decrease in their number can lead to significant health risks.
  • The onset of TTS is linked to the immune response to the vaccine. Specifically, the body produces antibodies that mistakenly attack a protein essential for clotting, leading to both thrombosis and thrombocytopenia.

Classification of TTS

The Centers for Disease Control and Prevention (CDC) classifies TTS into two tiers based on severity and symptoms:

Tier 1:

  • Involves rare and severe clotting events such as cerebral venous sinus thrombosis (brain) or splanchnic vein thrombosis (gut).
  • Accompanied by a significantly low platelet count (below 150,000 per microliter).
  • Diagnosis can be supported by a positive anti-PF4 ELISA test, although it is not mandatory for all cases.
  • This tier is more commonly observed in younger individuals and is considered more severe.

Tier 2:

  • Consists of more common thrombotic events, such as deep vein thrombosis (legs) or pulmonary embolism (lungs).
  • Also features low platelet counts similar to Tier 1.
  • A positive anti-PF4 ELISA test is essential for confirming diagnosis in Tier 2 cases.

Symptoms of TTS

The symptoms of TTS can vary but typically include:

  • Severe headaches
  • Stomach pain
  • Swelling in the legs
  • Difficulty breathing
  • Cognitive impairments or seizures

If these symptoms appear following vaccination, it is crucial to seek medical attention immediately to manage the condition effectively.

Thrombosis with thrombocytopenia syndrome treatment

Thrombosis with thrombocytopenia syndrome (TTS) is a newly recognized condition. Due to its similarity to heparin-induced thrombocytopenia (HIT), treatment strategies typically follow those used for HIT, adapting as more is learned about TTS. Treatment commonly involves:

  • Intravenous Immunoglobulin (IVIG) Infusions: Administered to mitigate the immune response associated with TTS.
  • Non-Heparin Anticoagulants: Used instead of heparin to manage thrombosis without worsening thrombocytopenia.

Treatments are personalized, with healthcare providers possibly recommending additional strategies based on individual patient conditions.

Lifestyle Changes to Manage TTS:

Thrombosis with thrombocytopenia syndrome (TTS) requires careful lifestyle management. Here’s how you can minimize risks:

  • Quit Smoking: Stop smoking to significantly reduce your risk of blood clots.
  • Moderate Alcohol: Limit alcohol intake to avoid affecting platelet levels crucial for clotting.
  • Good Dental Hygiene: Maintain oral health to prevent bleeding from dental treatments.
  • Choose Safe Activities: Avoid contact sports like football or basketball to reduce injury risks. Consult with healthcare providers for safer activity alternatives.
  • Travel Safely: Always wear a seatbelt to decrease injury risk in accidents.
  • Inform Healthcare Providers: Share your medication details with healthcare providers before any surgery or dental procedure to manage bleeding risks.

Diet Recommendations:

  • Consume: Fresh fruits and vegetables for essential vitamins; nuts, seeds, and avocados for healthy fats.
  • Avoid: Foods that can interfere with clotting (e.g., red grapes, blueberries, garlic, onions, ginger), especially in large quantities; foods high in saturated or trans fats; refined grains and added sugars; alcoholic beverages completely.

When to Worry?

After receiving the Covishield vaccine, most side effects are generally mild and resolve without the need for medical intervention. However, certain symptoms should prompt immediate medical attention. These symptoms may indicate serious, potentially life-threatening conditions. If you experience any of the following after being vaccinated, it is crucial to seek emergency medical care promptly:

  • Shortness of Breath: Difficulty breathing can be a sign of a severe allergic reaction or pulmonary issues.
  • Chest Pain: This could indicate cardiac complications, which are rare but serious.
  • Leg Swelling: Swelling in the legs can be a symptom of deep vein thrombosis (DVT), a blood clot that requires immediate treatment.
  • Severe Headache: If you experience a headache that is more severe than typical headaches or does not go away, it might signify a more severe condition, such as a blood clot in the brain.
  • Bruising or Bleeding: Unusual bruising or bleeding can suggest a bleeding disorder, which might be triggered by an immune response.
  • Severe Abdominal Pain: This pain could be an indicator of an abdominal blood clot or other serious abdominal conditions.
  • Vision Changes: Any sudden vision changes should be treated as urgent, as these could indicate a serious issue, including a stroke.
  • Unusual Rash: An unexpected rash can be a sign of an allergic reaction or other significant health issues.

If you encounter any of these symptoms following your vaccination, do not hesitate to seek medical help immediately.


TTS, although serious, remains an exceedingly rare condition. However, vaccine recipients need to be vigilant about their health post-vaccination.

Individuals who receive the Covishield vaccine should be aware of the symptoms of TTS and other severe side effects. Early intervention is key to effectively managing and treating TTS, thereby minimizing the risk of severe outcomes. Consulting with a healthcare provider can provide personalized guidance based on individual health profiles and help mitigate concerns about the vaccine.