Global covid-19 vaccine rollout and safety surveillance—how to keep pace
Vincent Lo Re III, Olaf H Klungel, K Arnold Chan, Catherine A Panozzo, Wei Zhou, Almut G Winterstein
The first vaccines against the novel pathogenSARS-CoV-2 were deployed just nine months afterthe covid-19 outbreak was declared a globalpandemic. Several types of covid-19 vaccines havebeen developed using different platforms andadjuvants, including messenger RNA based vaccines,adenovirus based vector vaccines, and inactivatedvaccines.1As of June 2021, 102 vaccines were understudy in phase I-III trials, and 185 were underinvestigation in preclinical studies.2Given the global impact of the pandemic, vaccinedevelopment received unprecedented public andpolitical attention, resulting in accelerated regulatoryreview. However, there has been scepticism aboutthe rigour of evidence supporting comprehensivebenefit-risk assessments and concern thatbreakthroughs in vaccine development have not beenaccompanied by similar advances in systems tomonitor adverse events or communicate safety signalsamong regulators, public health officials, andhealthcare providers.3 -5The limited human exposureand follow-up within the pivotal covid-19 vaccinetrials, optimised to allow formal conclusions aboutefficacy, did not permit detection of rare adverseevents (occurring in fewer than 1 in 10 000 people)after immunisation, particularly within subgroupsunder-represented in, or excluded from, those trials(such as pregnant women, children, and frail elderlyor immunocompromised people).6 7Publicapprehension about the safety of covid-19 vaccineshas contributed to hesitancy to receive a vaccine.8These concerns were heightened in February 2021,when cases of unusual blood clotting occurring afterimmunisation with the Oxford-AstraZeneca vaccine(ChAdOx1-S) were reported to regulatory agencies(box 1).9The timely detection of rare, serious eventsafter covid-19 vaccination highlights the importanceof robust safety surveillance systems. As countriesroll out covid-19 vaccines to their populations, speedof safety assessments is crucial to ensure favourablebenefit-risk profiles and preserve public trust. Wehighlight potential challenges in covid-19 vaccineglobal safety surveillance and suggest approachesto overcome them.