All ‘Adverse Events Following Immunisation’ (AEFI) after COVID-19 vaccinations continue to be monitored, a senior Union Health Ministry official, who did not wish to be named, said on Thursday.
Earlier this week, the pharmaceutical company AstraZeneca has admitted in a U.K. court that its COVID-19 vaccine had the potential to cause thrombosis with thrombocytopenia syndrome (TTS), a rare side effect associated with blood clotting.
“After 2022-23, the demand for COVID vaccine dropped and now we are seeing less than a lakh people coming in for vaccination or the booster dose. In India, all vaccine-related AEFI are routinely monitored and COVID is no exception,” N.K. Arora, who has been a part of the National Technical Advisory Group on Immunisation (NTAGI), said.
While doctors in India maintained that the information on TTS was nothing new, a senior Health Ministry official said: “It’s pertinent to note that TTS can also occur in the absence of vaccination.’’
In India, vaccines against the COVID-19 pandemic were introduced in late 2020 and were approved under the Emergency Use Listing (EUL).
According to a study titled ‘Serious adverse event following immunization and thromboembolic events associated with COVID19 vaccination: An analysis of nationwide causality assessment from India’, published in February 2023, the majority of serious AEFIs assessed for the study were either coincidental (578 cases; 52%) or vaccine product-related (218 cases; 19.6%).
All the serious AEFIs were reported from recipients of Covishield (992 cases, 89.2%) and Covaxin (120 cases, 10.8%) vaccines. Among them, 401 cases (36.1%) resulted in death, and 711 cases (63.9%) resulted in hospitalisation followed by recovery.
On adjusted analysis, females, the younger age group and non-fatal AEFIs showed a statistically significant consistent causal association with COVID-19 vaccination. Thromboembolic events were reported among 209 (18.8%) of the analysed participants, with a significant association between higher age and case fatality rate.
For this analysis, all the reports published till March 29, 2022 were included, and the causality assessment report for 1,112 serious AEFIs has been published in India for COVID-19 vaccination, the study noted.
The study concluded that the deaths reported under serious AEFIs were found to have a relatively lower consistent causal relationship with COVID-19 vaccines than the recovered hospitalisations in India. No consistent causal association was found between the thromboembolic events and the type of COVID-19 vaccine administered in India.
Thromboembolic events were reported among 209 cases (18.8%) of the analysed participants. Among the ones with thromboembolic events, acute coronary syndrome (96 cases; 45.9%) followed by cerebrovascular accidents (77 cases; 36.8%) were reported to be the most common. They were followed by myocardial infarction (54 cases, 25.8%).
The report further adds that India has a specific, passive AEFI reporting system for COVID-19 vaccines, in-built within the COWIN application. COWIN was formulated to enable beneficiary registration for COVID-19 vaccination in India.
India had reported more than 49,819 adverse events as of November 30, 2021. Within that, 1,965 serious adverse events were reported.
According to global data on TTS available in the public domain, as on January 5, 2024, Canada had reported 89 cases of TTS, of which 56 cases were reported following vaccination with AstraZeneca’s Vaxzevria/Covishield COVID-19 vaccine, and 24 cases were reported following vaccination with Pfizer-BioNTech’s Comirnaty COVID-19 vaccine. Eight cases were also reported following vaccination with Moderna’s Spikevax COVID-19 vaccine.
“In the U.K., 122 cases of TTS following the administration of the AstraZeneca vaccine have been reported as on November 2023,” a senior health expert said.
