…U/mL only after the second dose (Mulligan et al. Nature 2020;586:589-593. www.nature.com/articles/s41586-020-2639-4.pdf). However, RBD-binding IgG titres were not substantially lower than what was seen in patients who had recovered from COVID-19 or had received convalescent serum (602 U/mL). It has not been determined if antibody levels following a single dose will be sustained for up to 16 weeks, or if delaying the second dose will impair the ov…

…be used in adults under age 55 years due to concerns about a rare clotting complication (www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/rapid-response-recommended-use-astrazeneca-covid-19-vaccine-younger-adults.html). Individuals aged >55 years can still receive the vaccine. NACI previously recommended that the vaccine not be used in individuals aged >65 years due to a lack of evidence. The mo…

…it plans to release the results from its primary analysis later this week (www.astrazeneca.com/content/astraz/media-centre/press-releases/2021/update-following-statement-by-niaid-on-azd1222-us-phase-iii-trial-data.html). A further issue that has plagued the AstraZeneca vaccine is the link to rare thrombotic complications. To date, the European Medicines Agency has recorded 18 cases of cerebral venous sinus thrombosis (CVST) in approximately 20 mil…

…r pro-coagulant effects on platelets (Bollmann A. Br Med J, 16 March 2021. www.bmj.com/content/372/bmj.n699/rapid-responses). At present, it is not known if thrombocytopenia/thromboembolism is associated with COVID-19 vaccination, or if the incidence of these complications is uniquely higher with the AstraZeneca vaccine. It also remains to be determined if pre-existing thrombocytopenia, as seen in some treated multiple sclerosis patients, increase…

…do not contain live virus and viral mRNA does not enter host cell nuclei (www.cdc.gov/coronavirus/2019-ncov/vaccines/recommendations/pregnancy.html). The American College of Obstetricians and Gynecologists recommends that COVID-19 vaccines should not be withheld from pregnant or lactating women (www.acog.org/clinical/clinical-guidance/practice-advisory/articles/2020/12/vaccinating-pregnant-and-lactating-patients-against-covid-19). The Academy of…