Preliminary data suggest that inactivated vaccine-induced neutralizing antibodies against SARS-CoV-2 decrease at six months after vaccination. Observational, unpublished data also indicate that vaccine effectiveness against Covid-19 wanes over time. Thus, the investigators aimed to determine the reactogenicity, safety, and immunogenicity of a homologous or heterologous booster of SARS-CoV-2 vaccines among people already immunized with an inactivated SARS-CoV-2 vaccine. The study focuses on the elderly population and healthcare workers.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
534
0.3 mL IM saline solution
0.5 mL IM
0.3 mL IM
ELEAMs (Nursing Homes)
Santiago, Chile
Hospital de Urgencia Asistencia Publica
Santiago, Chile
Early humoral response
Change in SARS-CoV-2 neutralizing antibody levels
Time frame: Baseline (90-120 days after second dose of CoronaVac) and 15 days post booster dose
Immunogenicity
Change in SARS-CoV-2 neutralizing antibody levels
Time frame: Baseline, 15, 30, 60, and 90 days post booster dose
Reactogenicity
Solicited and unsolicited. Events will be assessed by scheduled visits performed by nursing home´s nurse stuff. Telephone numbers, including the PI´s cell phone will be available 24/7 for reporting any unsolicited reaction. Reporting will follow national regulations available at the Institute of Public Health web page (https://www.ispch.cl/anamed/farmacovigilancia/vacunas/como-notificar-esavi/)
Time frame: days 7, 28, and 3 months post booster dose
Safety of booster dose
Number of subjects presenting serious adverse events post booster dose.
Time frame: In addition to the scheduled visits mentioned in Outcome 3, Telephone numbers, including the PI´s cell phone will be available 24/7 throughout the study (1 year) for reporting any unsolicited reaction.
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0.5 mL IM