inclusion criteria: participants must meet all of the following criteria to be eligible to participate in this study: 1. individuals \> / = 18 years of age at the time of consent. (18-49 years for stage 4). 2. confirmed receipt of a complete primary and booster covid-19 vaccine series, either homologous or heterologous, with an fda authorized/approved vaccine at least 16 weeks prior to study vaccine dose 1. 3. willing and able to comply with all scheduled visits, vaccination plan, laboratory tests and other study procedures. 4. determined by medical history, targeted physical examination and clinical judgement of the investigator to be in stable state of health. note: participants with pre-existing stable chronic medical conditions defined as condition not requiring significant change in therapy or hospitalization for worsening disease within 4 weeks from enrollment, can be included at the discretion of the investigator.

inclusion criteria: participants must meet all of the following criteria to be eligible to participate in this study: 1. individuals \> / = 18 years of age at the time of consent. (18-49 years for stage 4). 2. confirmed receipt of a complete primary and booster covid-19 vaccine series, either homologous or heterologous, with an fda authorized/approved vaccine at least 16 weeks prior to study vaccine dose 1. 3. willing and able to comply with all scheduled visits, vaccination plan, laboratory tests and other study procedures. 4. determined by medical history, targeted physical examination and clinical judgement of the investigator to be in stable state of health. note: participants with pre-existing stable chronic medical conditions defined as condition not requiring significant change in therapy or hospitalization for worsening disease within 4 weeks from enrollment, can be included at the discretion of the investigator.

inclusion criteria: participants must meet all of the following criteria to be eligible to participate in this study: individuals > / = 18 years of age at the time of consent. (18-49 years for stage 4). confirmed receipt of a complete primary and booster covid-19 vaccine series, either homologous or heterologous, with an fda authorized/approved vaccine at least 16 weeks prior to study vaccine dose 1. willing and able to comply with all scheduled visits, vaccination plan, laboratory tests and other study procedures. determined by medical history, targeted physical examination and clinical judgement of the investigator to be in stable state of health. note: participants with pre-existing stable chronic medical conditions defined as condition not requiring significant change in therapy or hospitalization for worsening disease within 4 weeks from enrollment, can be included at the discretion of the investigator.

inclusion criteria: participants must meet all of the following criteria to be eligible to participate in this study: individuals > / = 18 years of age at the time of consent. (18-49 years for stage 4). confirmed receipt of a complete primary and booster covid-19 vaccine series, either homologous or heterologous, with an fda authorized/approved vaccine at least 16 weeks prior to study vaccine dose 1. willing and able to comply with all scheduled visits, vaccination plan, laboratory tests and other study procedures. determined by medical history, targeted physical examination and clinical judgement of the investigator to be in stable state of health. note: participants with pre-existing stable chronic medical conditions defined as condition not requiring significant change in therapy or hospitalization for worsening disease within 4 weeks from enrollment, can be included at the discretion of the investigator.

inclusion criteria: participants must meet all of the following criteria to be eligible to participate in this study: individuals > / = 18 years of age at the time of consent. confirmed receipt of a complete primary and booster covid-19 vaccine series, either homologous or heterologous, with a federal drug administration (fda) authorized/approved vaccine at least 16 weeks prior to study vaccine dose 1. willing and able to comply with all scheduled visits, vaccination plan, laboratory tests and other study procedures. determined by medical history, targeted physical examination and clinical judgement of the investigator to be in stable state of health. note: participants with pre-existing stable chronic medical conditions defined as condition not requiring significant change in therapy or hospitalization for worsening disease within 4 weeks from enrollment, can be included at the discretion of the investigator.

inclusion criteria: participants must meet all of the following criteria to be eligible to participate in this study: individuals > / = 18 years of age at the time of consent. confirmed receipt of a complete primary and booster covid-19 vaccine series, either homologous or heterologous, with a federal drug administration (fda) authorized/approved vaccine at least 16 weeks prior to study vaccine dose 1. willing and able to comply with all scheduled visits, vaccination plan, laboratory tests and other study procedures. determined by medical history, targeted physical examination and clinical judgement of the investigator to be in stable state of health. note: participants with pre-existing stable chronic medical conditions defined as condition not requiring significant change in therapy or hospitalization for worsening disease within 4 weeks from enrollment, can be included at the discretion of the investigator.