What WHO said on TTS risk from covid vaccines
In 2023, the World Health Organization (WHO) reported the emergence of Thrombotic Thrombocytopenia Syndrome (TTS) as a rare adverse event associated with COVID-19 non-replicant adenovirus vector-based vaccines, epecifically, individuals vaccinated with AstraZeneca’s ChAdOx-1 vaccine and Johnson & Johnson’s Janssen COVID-19 Ad26.COV2-S vaccine.
“Knowledge about TTS following vaccination with a COVID-19 adenovirus vector-based vaccine is rapidly evolving. WHO will continue to monitor the situation closely for any changes that may affect this interim guidance and will update the guidance as needed,” WHO said in its April 2023 report.
In patients exhibiting platelet-activating anti-PF4 (PF4) antibodies, this condition has been identified as vaccine-induced immune thrombotic thrombocytopenia (VITT). Some individuals may experience delayed-onset symptoms, such as persistent headaches lasting at least three days, with unusual characteristics and warning signs like treatment resistance and progressively worsening headaches, even in the absence of cerebral thrombosis, WHO said. This condition is termed pre-VITT syndrome if these patients exhibit other typical VITT features, including decreased platelet count, elevated D-dimer levels, and the presence of anti-PF4 antibodies. Pre-VITT syndrome may indicate an early stage of VITT, underscoring the importance of prompt identification and early treatment to prevent major thrombosis development, WHO said.
Recent epidemiological data suggests that the cumulative incidence of TTS is higher following the initial dose of the COVID-19 vaccine compared to subsequent doses, the world health body said.
TTS should be suspected in patients presenting with severe, persistent, or unusual symptoms such as headaches, blurred vision, weakness or numbness, abdominal pain, breathing difficulties, chest pain, limb swelling or pain, and unusual skin bruising or petechiae within 3 to 30 days following vaccination, WHO said, adding that such patients should undergo prompt investigations to assess thrombotic events and the presence of thrombocytopenia.Individuals who develop thrombosis shortly after vaccination, typically within 3 to 30 days, should be evaluated for thrombocytopenia, increased D-dimer levels, and positive anti-PF4 antibodies.
WHO Recommendations Summary:
- Anti-coagulation treatment is recommended for all patients presenting with TTS following COVID-19 vaccination.
- Heparin may be used for anti-coagulation in individuals with TTS following COVID-19 vaccination in settings where non-heparin-based anticoagulants (NHACs) are not available.
- Intravenous immunoglobulins (IVIGs) or NHACs are recommended for individuals with TTS following COVID-19 vaccination.
- Platelet transfusion is not recommended for TTS patients following COVID-19 vaccination except in emergency situations necessitating surgery, severe thrombocytopenia (<50 x 109 platelets /L), or bleeding.
- No recommendation is provided for steroid treatment due to insufficient evidence, but steroids may be administered in combination with other treatments.
What an ex-AIIMS doctor says
Dr. MV Padma Srivastava presently serves as the Chairperson of Neurology at Paras Hospitals, Gurugram, and previously held the position of Head of the Department of Neurology at AIIMS, where she played an active role during the COVID-19 pandemic. “Although we do observe such instances, they represent a small percentage when compared to the significant number of cases where vaccines effectively prevent severe illnesses,” she stated.
