inclusion criteria: * healthy men and non-pregnant women at least 18 years of age; * able and willing to comply with all study procedures; * screening laboratory results within normal limits or deemed not clinically significant by the investigator; * received full primary series doses of an approved or authorized mrna vaccine at least 6 months but no more than 12 months prior to ino-4800 booster dose. * must meet one of the following criteria with respect to reproductive capacity: * women who are post-menopausal as defined by reported spontaneous amenorrhea for ≥ 12 months; * surgically sterile (i.e., vasectomy in males or tubal ligation, absence of ovaries and/or uterus in females). in the case of vasectomy, participants should wait six (6) months post-vasectomy prior to enrollment; * use of medically effective contraception with a failure rate of \< 1% per year when used consistently and correctly from screening until day 28 post booster dose.

inclusion criteria: * healthy men and non-pregnant women at least 18 years of age; * able and willing to comply with all study procedures; * screening laboratory results within normal limits or deemed not clinically significant by the investigator; * received full primary series doses of an approved or authorized mrna vaccine at least 6 months but no more than 12 months prior to ino-4800 booster dose. * must meet one of the following criteria with respect to reproductive capacity: * women who are post-menopausal as defined by reported spontaneous amenorrhea for ≥ 12 months; * surgically sterile (i.e., vasectomy in males or tubal ligation, absence of ovaries and/or uterus in females). in the case of vasectomy, participants should wait six (6) months post-vasectomy prior to enrollment; * use of medically effective contraception with a failure rate of \< 1% per year when used consistently and correctly from screening until day 28 post booster dose.

inclusion criteria: healthy men and non-pregnant women at least 18 years of age; able and willing to comply with all study procedures; screening laboratory results within normal limits or deemed not clinically significant by the investigator; received full primary series doses of an approved or authorized mrna vaccine at least 6 months but no more than 12 months prior to ino-4800 booster dose. must meet one of the following criteria with respect to reproductive capacity: women who are post-menopausal as defined by reported spontaneous amenorrhea for ≥ 12 months; surgically sterile (i.e., vasectomy in males or tubal ligation, absence of ovaries and/or uterus in females). in the case of vasectomy, participants should wait six (6) months post-vasectomy prior to enrollment; use of medically effective contraception with a failure rate of < 1% per year when used consistently and correctly from screening until day 28 post booster dose.

inclusion criteria: healthy men and non-pregnant women at least 18 years of age; able and willing to comply with all study procedures; screening laboratory results within normal limits or deemed not clinically significant by the investigator; received full primary series doses of an approved or authorized mrna vaccine at least 6 months but no more than 12 months prior to ino-4800 booster dose. must meet one of the following criteria with respect to reproductive capacity: women who are post-menopausal as defined by reported spontaneous amenorrhea for ≥ 12 months; surgically sterile (i.e., vasectomy in males or tubal ligation, absence of ovaries and/or uterus in females). in the case of vasectomy, participants should wait six (6) months post-vasectomy prior to enrollment; use of medically effective contraception with a failure rate of < 1% per year when used consistently and correctly from screening until day 28 post booster dose.