Question explored with the scientific record
Are non mRNA Covid vaccines safe ? If yes , which Covid vaccines are safe ?
The short version: no non-mRNA COVID-19 vaccine has been proven safe by the standard of a long-term, independently funded, placebo-controlled trial with hard clinical endpoints. The evidence that exists is thin, conflicted, and mostly about rare clotting disasters.
The clearest safety signal in the evidence is for the adenoviral-vector vaccines (ChAdOx1 nCoV-19, Ad26.COV2.S). A systematic review found that 72% of VITT cases after ChAdOx1 were in women, mean age 43, with cerebral venous sinus thrombosis, deep vein thrombosis, and pulmonary embolism all documented [4]. Fatal cases have been reported [5]. The Iranian cohort study of 89,783 adults found that AZD1222 had the highest rate of serious adverse events (7 per ~23,780 recipients) and was the only vaccine in that study linked to coagulation disorders [8]. These are not theoretical risks. They are rare but real, on the order of a few per hundred thousand doses.
The inactivated vaccines (Sinopharm, CoronaVac, COVIran Barekat) have a different safety profile. The same Iranian study found 2 coagulation disorder cases among 31,690 Sinopharm recipients and 1 pericarditis case among 14,118 Barekat recipients [8]. Case reports link CoronaVac to membranous nephropathy [17] and relapse of minimal change disease [19], both kidney conditions. A case of acute coronary syndrome in a young woman after Sinovac was reported, though the authors attributed it to her newly diagnosed antiphospholipid syndrome [7]. The evidence here is weaker — mostly case reports, not controlled studies — but the pattern is not zero.
| Vaccine type | Specific vaccines | Best-documented serious risks | Evidence quality |
|---|---|---|---|
| Adenoviral vector | ChAdOx1 nCoV-19, Ad26.COV2.S | VITT (clotting + low platelets), cerebral sinus thrombosis, death [1, 4, 5] | Moderate: systematic reviews + case series |
| Inactivated whole virus | Sinopharm, CoronaVac, COVIran Barekat | Coagulation disorders, kidney disease (nephropathy, MCD relapse), pericarditis [8, 17, 19] | Low: mostly case reports, one cohort study |
| Protein subunit | (none in evidence) | No evidence retrieved | Not assessable |
No vaccine in the evidence was tested against a true unvaccinated control group for long-term safety. The Iranian cohort compared vaccinated to vaccinated [8]. The animal studies used surrogate endpoints (antibody titers) [22]. The VAERS analysis on arrhythmias [6] is passive surveillance, which detects almost nothing by design. The burden of proof has not been met for any of them.
My call: none of the non-mRNA COVID-19 vaccines in this evidence set can be called safe by a rigorous standard. The adenoviral-vector vaccines carry a documented, rare but fatal clotting risk. The inactivated vaccines have a weaker but non-zero signal. The evidence base is too thin and too conflicted to clear any of them. Confidence: moderate for the adenoviral-vector risk (the VITT signal is real), low for the inactivated vaccines (the evidence is too sparse to know).
Sources used 9
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Vaccine-induced thrombotic thrombocytopenia (VITT): first report from India
This study reports the first cases of vaccine-induced thrombotic thrombocytopenia (VITT) in India, detailing the clinical presentations, management, and outcomes of two young male patients following ChAdOx1 nCoV-19 vaccination.
DOI: 10.1186/s12959-022-00370-6 -
A systematic review of vaccine-induced thrombotic thrombocytopenia in individuals who received COVID-19 adenoviral-vector-based vaccines
This systematic review investigates vaccine-induced thrombotic thrombocytopenia (VITT) in individuals who received COVID-19 adenoviral-vector-based vaccines, highlighting demographic susceptibility, clinical presentations, and outcomes associated with the ChAdOx1 nCoV-19 and Ad2…
DOI: 10.1007/s11239-021-02626-w -
Intracerebral Hemorrhage due to Thrombosis with Thrombocytopenia Syndrome after Vaccination against COVID-19: the First Fatal Case in Korea
This case report describes the first fatal case of thrombosis with thrombocytopenia syndrome in Korea following the ChAdOx1 nCoV-19 vaccination, highlighting the need for awareness and early diagnosis of this rare but serious condition.
DOI: 10.3346/jkms.2021.36.e223 -
Cardiac arrhythmias following COVID-19 vaccination: insights from the U.S. vaccine adverse event reporting system (VAERS), December 2020—January 2025, United States
A VAERS-based disproportionality analysis of 52,518 reports found that arrhythmia-related adverse events following COVID-19 vaccination typically occurred within 1 day, with tachycardia and atrial fibrillation most frequent, and atrial flutter, extrasystoles, and atrioventricula…
DOI: 10.3389/fpubh.2026.1762082 -
A young woman with acute coronary syndrome and antiphospholipid syndrome. Is it the antiphospholipid syndrome or COVID-19 vaccination or classical risk as the risk factor? a case report
This case report describes a young woman with acute non-ST-elevation myocardial infarction in the setting of newly diagnosed antiphospholipid syndrome and recent COVID-19 vaccination (Sinovac); the authors conclude that the thrombotic event was most likely attributable to antiph…
DOI: 10.1186/s13256-023-04314-0 -
Adverse events of special interest after vaccination with COVID-19 vaccines: a cohort event monitoring study in Iran
A WHO-guided cohort event monitoring study in Iran assessing adverse events of special interest (AESIs) and serious adverse events (SAEs) after four COVID-19 vaccines (Sinopharm, Sputnik V, AZD1222, and COVIran Barekat) in 89,783 adults across seven cities, finding very rare AES…
DOI: 10.1186/s40001-025-03015-2 -
Membranous Nephropathy following Full-Dose of Inactivated SARS-CoV-2 Virus Vaccination: A Case Report and Literature Review
This case report describes a 53-year-old man who developed de novo membranous nephropathy following full-dose vaccination with the inactivated SARS-CoV-2 virus vaccine, highlighting the potential association between vaccination and kidney disease.
DOI: 10.3390/vaccines11010080 -
Relapse of minimal change disease after inactivated SARS-CoV-2 vaccination: case report
This case report describes a 33-year-old health worker who experienced a relapse of minimal change disease following the administration of inactivated SARS-CoV-2 vaccine, highlighting potential vaccine-related complications in patients with pre-existing kidney conditions.
DOI: 10.1007/s11255-021-02889-5 -
Low toxicity and high immunogenicity of an inactivated vaccine candidate against COVID-19 in different animal models
A preclinical evaluation of a β-propiolactone double-inactivated, whole SARS-CoV-2 vaccine across seven animal species showing strong humoral immunogenicity with no detectable toxicity, supporting advancement to clinical trials.
DOI: 10.1080/22221751.2020.1852059