Abstract This study describes the incidence of early events supposedly attributable to vaccination or immunization (ESAVI) that occurred in healthcare workers who had been inoculated with the first component of the Sputnik V vaccine. Safety at 72 h post-immunization was analyzed based on a self-reported form. Between January 5 and January 20, 2021, in Buenos Aires, Argentina, a total of 707 healthcare workers (median age 35 yrs, female 67%) were vaccinated. The response rate was 96.6% (n: 683) and 487 (71.3%) participants reported at least one ESAVI. The incidence rate was 6.3 per 1000 person/hours. The total number of ESAVIs was 1434. A total of 469 local reactions were reported, 57% of the participants reported pain at the injection site, and 11% had redness and swelling. A total of 968 systemic reactions were informed, including new or worsened muscle pain, referred by 58% of the participants, fever referred by 40%, and diarrhea referred by 5%. Five percent (n: 34) had serious adverse events and one participant had to be hospitalized. The ESAVI rate was higher in females than males (66.4% versus 51.4%; HR 1.38; 95% CI 1.13-5.38) and in workers younger than 55 yrs old (63.0% versus 28.0%; HR 2.66; 95% CI 1.32-5.38). This study demonstrates high rates of early local and systemic reactions. However, serious events were rare. Studies on long-term safety, stratified by sex and age, are needed.