ABSTRACT
Cases that experienced COVID-19 postvaccination-related thrombosis have been reported after the first dose of ChAdOx1 nCov-19 (Vaxzevria, AstraZeneca) or Ad26.COV2.S (Johnson & Johnson/Janssen) vaccine. These rare thrombotic events were observed within the expected vaccine-induced seroconversion period and could be attributed to platelet-activating (auto)antibodies against platelet factor 4 (PF4). Newly, vaccine-induced, cross-reactive anti-PF4 antibodies could explain this observation. An in-silico analysis using the Basic Local Alignment Search Tool was used to identify sequence similarity between PF4 and antigens contained in or encoded by ChAdOx1 nCov-19 or Ad26.COV2.S vaccines. Only one sequence within the signaling peptide of the SARS-CoV-2 spike protein exhibited a high percent identity (85.71%) with PF4. This sequence overlaps with a proven immunogenic peptide recognized from convalescent COVID-19 sera and could be responsible for the formation of platelet-activating immunocomplexes in susceptible patients. Manipulation of the immunogenicity of this particular sequence within the encoded SARS-CoV-2 spike protein signaling peptide may eliminate this iatrogenic severe adverse effect.
Subject(s)
COVID-19 , Purpura, Thrombocytopenic, Idiopathic , Thrombocytopenia , Thrombosis , Ad26COVS1/adverse effects , COVID-19/prevention & control , ChAdOx1 nCoV-19/adverse effects , Humans , Platelet Factor 4 , Purpura, Thrombocytopenic, Idiopathic/chemically induced , SARS-CoV-2 , Spike Glycoprotein, Coronavirus , Thrombosis/chemically inducedABSTRACT
Breastfeeding not only provides the optimum source of nutrients for the neonate and its first strong shield against infection but also lays the foundation for somatic and psychological bonding between the mother and child. During the current COVID-19 pandemic, although the guidelines of the relevant international and national agencies recommend breastfeeding by SARS-CoV-2-infected mothers, considerable insecurity persists in daily clinical practice regarding the safety of the infants and the perceived advantages and disadvantages of discontinuation of breastfeeding. This is a systematic review of the currently available information regarding the transmissibility of SARS-CoV-2 through or while breastfeeding and the protection against infection that breast milk might provide. The accumulated body of knowledge regarding the role of breast milk in the development of the neonatal immune system and protection against infection by other respiratory viruses is discussed, with a focus on the anti-inflammatory role of the antibodies, microbes, and viruses provided to the infant in breast milk and its relevance to the case of SARS-CoV-2.