Evaluation of retinal and optic disc vascular structures in individuals before and after Pfizer-BioNTech vaccination

Evaluation of the early effects of the first-dose administration of the Sinovac vaccine on the retina, choroid, and optic disc using optical coherence tomography (OCT) and OCT-angiography

AIM

To determine the effects of the first-dose administration of the Sinovac vaccine on the retina, choroid, and optic disc in healthy participants.

METHODS

This prospective design study was conducted with 27 healthy healthcare workers who received the first dose of Sinovac vaccine and 25 healthy controls who were not vaccinated. In the vaccinated group, ophthalmological examinations and measurements were performed before vaccination and one week and one month after vaccination. Subfoveal, nasal, and temporal choroidal thicknesses (CTs), retinal nerve fiber layer (RNFL) thickness, and macular thickness (MT) were determined using spectral domain-optical coherence tomography at all visits. Superficial, deep, and peripapillary radial capillary plexus (superficial capillary plexus, deep capillary plexus (DCP), and radial peripapillary capillary, respectively), choriocapillaris vascular density, and foveal avascular zone parameters were measured on optical coherence tomography-angiography (OCT-A).

RESULTS

No significant difference was detected between the two groups in terms of the parameters measured by OCT and OCT-A (p > 0.05 for all). The CT values measured in all quadrants were significantly higher at the first week after vaccination (p < 0.05 for all), and they returned to their pre-vaccination values at the first month post-vaccination measurement (p > 0.05 for all). Concerning the RNFL and MT values, there was no significant difference between the pre-vaccination and post-vaccination first-week measurements (p > 0.05 for all), but a statistically significant increase was detected in the post-vaccination first-month MT and RNFL measurements (p < 0.05 for all). Only the decreases in the foveal DCP and choriocapillaris vascular density values were significant at the first week after vaccination (p < 0.05 for all).

CONCLUSION

The early changes detected after vaccination in this study suggest the possibility that autoimmune, vascular, and inflammatory diseases may simultaneously emerge in the early post-vaccination period or may be triggered after vaccination, or that the vaccine may unmask these diseases.

Back to the Basics of SARS-CoV-2 Biochemistry: Microvascular Occlusive Glycan Bindings Govern Its Morbidities and Inform Therapeutic Responses

Consistent with the biochemistry of coronaviruses as well established over decades, SARS-CoV-2 makes its initial attachment to host cells through the binding of its spike protein (SP) to sialylated glycans (containing the monosaccharide sialic acid) on the cell surface. The virus can then slide over and enter via ACE2. SARS-CoV-2 SP attaches particularly tightly to the trillions of red blood cells (RBCs), platelets and endothelial cells in the human body, each cell very densely coated with sialic acid surface molecules but having no ACE2 or minimal ACE2. These interlaced attachments trigger the blood cell aggregation, microvascular occlusion and vascular damage that underlie the hypoxia, blood clotting and related morbidities of severe COVID-19. Notably, the two human betacoronaviruses that express a sialic acid-cleaving enzyme are benign, while the other three-SARS, SARS-CoV-2 and MERS-are virulent. RBC aggregation experimentally induced in several animal species using an injected polysaccharide caused most of the same morbidities of severe COVID-19. This glycan biochemistry is key to disentangling controversies that have arisen over the efficacy of certain generic COVID-19 treatment agents and the safety of SP-based COVID-19 vaccines. More broadly, disregard for the active physiological role of RBCs yields unreliable or erroneous reporting of pharmacokinetic parameters as routinely obtained for most drugs and other bioactive agents using detection in plasma, with whole-blood levels being up to 30-fold higher. Appreciation of the active role of RBCs can elucidate the microvascular underpinnings of other health conditions, including cardiovascular disease, and therapeutic opportunities to address them.

Sialylated Glycan Bindings from SARS-CoV-2 Spike Protein to Blood and Endothelial Cells Govern the Severe Morbidities of COVID-19

Consistent with well-established biochemical properties of coronaviruses, sialylated glycan attachments between SARS-CoV-2 spike protein (SP) and host cells are key to the virus's pathology. SARS-CoV-2 SP attaches to and aggregates red blood cells (RBCs), as shown in many pre-clinical and clinical studies, causing pulmonary and extrapulmonary microthrombi and hypoxia in severe COVID-19 patients. SARS-CoV-2 SP attachments to the heavily sialylated surfaces of platelets (which, like RBCs, have no ACE2) and endothelial cells (having minimal ACE2) compound this vascular damage. Notably, experimentally induced RBC aggregation in vivo causes the same key morbidities as for severe COVID-19, including microvascular occlusion, blood clots, hypoxia and myocarditis. Key risk factors for COVID-19 morbidity, including older age, diabetes and obesity, are all characterized by markedly increased propensity to RBC clumping. For mammalian species, the degree of clinical susceptibility to COVID-19 correlates to RBC aggregability with p = 0.033. Notably, of the five human betacoronaviruses, the two common cold strains express an enzyme that releases glycan attachments, while the deadly SARS, SARS-CoV-2 and MERS do not, although viral loads for COVID-19 and the two common cold infections are similar. These biochemical insights also explain the previously puzzling clinical efficacy of certain generics against COVID-19 and may support the development of future therapeutic strategies for COVID-19 and long COVID patients.

Effects of Sinovac-Coronavac and Pfizer-BioNTech mRNA vaccines on choroidal and retinal vascular system

PURPOSE

To evaluate the effects of Sinovac-Coronavac and Pfizer-BioNTech mRNA vaccines on choroidal and retinal vascular system using enhanced depth imaging optical coherence tomography (EDI-OCT) and optical coherence tomography angiography (OCTA).

METHODS

In this prospective cross-sectional study, 63 healthy participants (29 with Pfizer-BioNTech, 34 with Sinovac-CoronaVac) were evaluated after the first dose of vaccination. Vessel density (VD) of the superficial (SCP), deep capillary plexus (DCP) and choriocapillaris (CC) were measured with OCTA. Choroidal thickness (CT) were measured with EDI-OCT. Measurements were performed at the 2nd week and the 4th week after vaccinations and compared to pre-vaccination values.

RESULTS

Regarding Pfizer-BioNTech vaccination, CT in the subfoveal and nasal region significantly increased between the pre-vaccination and post-vaccination 2nd week and then significantly decreased to pre-vaccine values at 4th week. The SCP-VD (whole image, fovea, parafovea, perifovea temporal) variables showed a significant decrease at 2nd week. The DCP-VD inferior hemi, parafovea inferior hemi, parafovea inferior variables demonstrated a significant decrease at 2nd week. The perifovea DCP-VD variables also showed a significant decrease at 2nd week, and these variables returned to pre-vaccination values after 4 weeks. The CC-VD variables showed a significant decrease between pre-vaccine and 2nd week post-vaccination. Regarding the Sinovac-CoronaVac vaccination, there was no statistically significant difference in CT and VD values before and after vaccination (p> 0.05).

CONCLUSION

Our study showed significant alterations in retinal vascular density and CT for the Pfizer-BioNTech vaccine at the 2nd week, and these parameters became compatible with pre-vaccination values at the 4th week. In contrast, no differences were observed after the Sinovac-Coronovac vaccination.