Effectiveness of an Inactivated SARS-CoV-2 Vaccine

• Published in: The New England journal of medicine Vol. 385; no. 14; pp. 1336 - 1339
• Main Authors: Okhotin, Artemy, Chi, Hsin, Chiu, Nan-Chang, Lin, Chien-Yu, Onishi, Franz J, Goto, Janaina M, Jara, Alejandro, Undurraga, Eduardo A, Araos, Rafael
• Format: Journal Article
• Language: English
• Published: United States Massachusetts Medical Society 30-09-2021
• Subjects: Age; Conflicts of interest; Coronaviruses; COVID-19; COVID-19 Vaccines; Humans; Immunization; Infections; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; Vaccination; Vaccines; Vaccines, Inactivated; Viral Vaccines; Brazil; Chile; Taiwan
• ISSN: 0028-4793; 1533-4406
• DOI: 10.1056/NEJMc2112423

To the Editor:
In the article by Jara and colleagues (Sept. 2 issue)
1
reporting a study of real-world efficacy of the CoronaVac vaccine against Covid-19, the authors provide a graph showing the incidences of infection among fully vaccinated, partially vaccinated, and unvaccinated participants. From this graph, the reader can conclude that partially vaccinated persons are especially vulnerable, since the incidence of infection is higher among them than among unvaccinated persons. This fact could have some causal explanation, but I suggest that it is purely a statistical artifact. The authors mention that vaccination status is a time-dependent variable, so for the . . .