* other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk of study participation or, in the investigator's judgment, make the participant inappropriate for the study. * phases 1 and 2 only: known infection with human immunodeficiency virus (hiv), hepatitis c virus (hcv), or hepatitis b virus (hbv). * history of severe adverse reaction associated with a vaccine and/or severe allergic reaction (eg, anaphylaxis) to any component of the study intervention(s). * receipt of medications intended to prevent covid 19. * previous clinical (based on covid-19 symptoms/signs alone, if a sars-cov-2 naat result was not available) or microbiological (based on covid-19 symptoms/signs and a positive sars-cov-2 naat result) diagnosis of covid 19 * phase 1 only: individuals at high risk for severe covid-19, including those with any of the following risk factors: * hypertension * diabetes mellitus * chronic pulmonary disease * asthma * current vaping or smoking * history of chronic smoking within the prior year * bmi \>30 kg/m2 * anticipating the need for immunosuppressive treatment within the next 6 months * phase 1 only: individuals currently working in occupations with high risk of exposure to sars-cov-2 (eg, healthcare worker, emergency response personnel). * immunocompromised individuals with known or suspected immunodeficiency, as determined by history and/or laboratory/physical examination. * phase 1 only: individuals with a history of autoimmune disease or an active autoimmune disease requiring therapeutic intervention. * bleeding diathesis or condition associated with prolonged bleeding that would, in the opinion of the investigator, contraindicate intramuscular injection. * women who are pregnant or breastfeeding. * previous vaccination with any coronavirus vaccine. * individuals who receive treatment with immunosuppressive therapy, including cytotoxic agents or systemic corticosteroids, eg, for cancer or an autoimmune disease, or planned receipt throughout the study. * phase 1 only: regular receipt of inhaled/nebulized corticosteroids. * receipt of blood/plasma products or immunoglobulin, from 60 days before study intervention administration or planned receipt throughout the study. * participation in other studies involving study intervention within 28 days prior to study entry through and including 6 months after the last dose of study intervention, with the exception of non-pfizer interventional studies for prevention of covid 19, which are prohibited throughout study participation. * previous participation in other studies involving study intervention containing lipid nanoparticles. * phase 1 only: positive serological test for sars-cov-2 igm and/or igg antibodies at the screening visit. * phase 1 only: any screening hematology and/or blood chemistry laboratory value that meets the definition of a ≥ grade 1 abnormality. * phase 1 only: positive test for hiv, hepatitis b surface antigen (hbsag), hepatitis b core antibodies (hbc abs), or hepatitis c virus antibodies (hcv abs) at the screening visit. * phase 1 only: sars-cov-2 naat-positive nasal swab within 24 hours before receipt of study intervention. * investigator site staff or pfizer employees directly involved in the conduct of the study, site staff otherwise supervised by the investigator, and their respective family members.

* other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk of study participation or, in the investigator's judgment, make the participant inappropriate for the study. * phases 1 and 2 only: known infection with human immunodeficiency virus (hiv), hepatitis c virus (hcv), or hepatitis b virus (hbv). * history of severe adverse reaction associated with a vaccine and/or severe allergic reaction (eg, anaphylaxis) to any component of the study intervention(s). * receipt of medications intended to prevent covid 19. * previous clinical (based on covid-19 symptoms/signs alone, if a sars-cov-2 naat result was not available) or microbiological (based on covid-19 symptoms/signs and a positive sars-cov-2 naat result) diagnosis of covid 19 * phase 1 only: individuals at high risk for severe covid-19, including those with any of the following risk factors: * hypertension * diabetes mellitus * chronic pulmonary disease * asthma * current vaping or smoking * history of chronic smoking within the prior year * bmi \>30 kg/m2 * anticipating the need for immunosuppressive treatment within the next 6 months * phase 1 only: individuals currently working in occupations with high risk of exposure to sars-cov-2 (eg, healthcare worker, emergency response personnel). * immunocompromised individuals with known or suspected immunodeficiency, as determined by history and/or laboratory/physical examination. * phase 1 only: individuals with a history of autoimmune disease or an active autoimmune disease requiring therapeutic intervention. * bleeding diathesis or condition associated with prolonged bleeding that would, in the opinion of the investigator, contraindicate intramuscular injection. * women who are pregnant or breastfeeding. * previous vaccination with any coronavirus vaccine. * individuals who receive treatment with immunosuppressive therapy, including cytotoxic agents or systemic corticosteroids, eg, for cancer or an autoimmune disease, or planned receipt throughout the study. * phase 1 only: regular receipt of inhaled/nebulized corticosteroids. * receipt of blood/plasma products or immunoglobulin, from 60 days before study intervention administration or planned receipt throughout the study. * participation in other studies involving study intervention within 28 days prior to study entry through and including 6 months after the last dose of study intervention, with the exception of non-pfizer interventional studies for prevention of covid 19, which are prohibited throughout study participation. * previous participation in other studies involving study intervention containing lipid nanoparticles. * phase 1 only: positive serological test for sars-cov-2 igm and/or igg antibodies at the screening visit. * phase 1 only: any screening hematology and/or blood chemistry laboratory value that meets the definition of a ≥ grade 1 abnormality. * phase 1 only: positive test for hiv, hepatitis b surface antigen (hbsag), hepatitis b core antibodies (hbc abs), or hepatitis c virus antibodies (hcv abs) at the screening visit. * phase 1 only: sars-cov-2 naat-positive nasal swab within 24 hours before receipt of study intervention. * investigator site staff or pfizer employees directly involved in the conduct of the study, site staff otherwise supervised by the investigator, and their respective family members.

- other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk of study participation or, in the investigator's judgment, make the participant inappropriate for the study. - phases 1 and 2 only: known infection with human immunodeficiency virus (hiv), hepatitis c virus (hcv), or hepatitis b virus (hbv). - history of severe adverse reaction associated with a vaccine and/or severe allergic reaction (eg, anaphylaxis) to any component of the study intervention(s). - receipt of medications intended to prevent covid 19. - previous clinical (based on covid-19 symptoms/signs alone, if a sars-cov-2 naat result was not available) or microbiological (based on covid-19 symptoms/signs and a positive sars-cov-2 naat result) diagnosis of covid 19 - phase 1 only: individuals at high risk for severe covid-19, including those with any of the following risk factors: - hypertension - diabetes mellitus - chronic pulmonary disease - asthma - current vaping or smoking - history of chronic smoking within the prior year - bmi >30 kg/m2 - anticipating the need for immunosuppressive treatment within the next 6 months - phase 1 only: individuals currently working in occupations with high risk of exposure to sars-cov-2 (eg, healthcare worker, emergency response personnel). - immunocompromised individuals with known or suspected immunodeficiency, as determined by history and/or laboratory/physical examination. - phase 1 only: individuals with a history of autoimmune disease or an active autoimmune disease requiring therapeutic intervention. - bleeding diathesis or condition associated with prolonged bleeding that would, in the opinion of the investigator, contraindicate intramuscular injection. - women who are pregnant or breastfeeding. - previous vaccination with any coronavirus vaccine. - individuals who receive treatment with immunosuppressive therapy, including cytotoxic agents or systemic corticosteroids, eg, for cancer or an autoimmune disease, or planned receipt throughout the study. - phase 1 only: regular receipt of inhaled/nebulized corticosteroids. - receipt of blood/plasma products or immunoglobulin, from 60 days before study intervention administration or planned receipt throughout the study. - participation in other studies involving study intervention within 28 days prior to study entry through and including 6 months after the last dose of study intervention, with the exception of non-pfizer interventional studies for prevention of covid 19, which are prohibited throughout study participation. - previous participation in other studies involving study intervention containing lipid nanoparticles. - phase 1 only: positive serological test for sars-cov-2 igm and/or igg antibodies at the screening visit. - phase 1 only: any screening hematology and/or blood chemistry laboratory value that meets the definition of a ≥ grade 1 abnormality. - phase 1 only: positive test for hiv, hepatitis b surface antigen (hbsag), hepatitis b core antibodies (hbc abs), or hepatitis c virus antibodies (hcv abs) at the screening visit. - phase 1 only: sars-cov-2 naat-positive nasal swab within 24 hours before receipt of study intervention. - investigator site staff or pfizer employees directly involved in the conduct of the study, site staff otherwise supervised by the investigator, and their respective family members.

- other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk of study participation or, in the investigator's judgment, make the participant inappropriate for the study. - phases 1 and 2 only: known infection with human immunodeficiency virus (hiv), hepatitis c virus (hcv), or hepatitis b virus (hbv). - history of severe adverse reaction associated with a vaccine and/or severe allergic reaction (eg, anaphylaxis) to any component of the study intervention(s). - receipt of medications intended to prevent covid 19. - previous clinical (based on covid-19 symptoms/signs alone, if a sars-cov-2 naat result was not available) or microbiological (based on covid-19 symptoms/signs and a positive sars-cov-2 naat result) diagnosis of covid 19 - phase 1 only: individuals at high risk for severe covid-19, including those with any of the following risk factors: - hypertension - diabetes mellitus - chronic pulmonary disease - asthma - current vaping or smoking - history of chronic smoking within the prior year - bmi >30 kg/m2 - anticipating the need for immunosuppressive treatment within the next 6 months - phase 1 only: individuals currently working in occupations with high risk of exposure to sars-cov-2 (eg, healthcare worker, emergency response personnel). - immunocompromised individuals with known or suspected immunodeficiency, as determined by history and/or laboratory/physical examination. - phase 1 only: individuals with a history of autoimmune disease or an active autoimmune disease requiring therapeutic intervention. - bleeding diathesis or condition associated with prolonged bleeding that would, in the opinion of the investigator, contraindicate intramuscular injection. - women who are pregnant or breastfeeding. - previous vaccination with any coronavirus vaccine. - individuals who receive treatment with immunosuppressive therapy, including cytotoxic agents or systemic corticosteroids, eg, for cancer or an autoimmune disease, or planned receipt throughout the study. - phase 1 only: regular receipt of inhaled/nebulized corticosteroids. - receipt of blood/plasma products or immunoglobulin, from 60 days before study intervention administration or planned receipt throughout the study. - participation in other studies involving study intervention within 28 days prior to study entry through and including 6 months after the last dose of study intervention, with the exception of non-pfizer interventional studies for prevention of covid 19, which are prohibited throughout study participation. - previous participation in other studies involving study intervention containing lipid nanoparticles. - phase 1 only: positive serological test for sars-cov-2 igm and/or igg antibodies at the screening visit. - phase 1 only: any screening hematology and/or blood chemistry laboratory value that meets the definition of a ≥ grade 1 abnormality. - phase 1 only: positive test for hiv, hepatitis b surface antigen (hbsag), hepatitis b core antibodies (hbc abs), or hepatitis c virus antibodies (hcv abs) at the screening visit. - phase 1 only: sars-cov-2 naat-positive nasal swab within 24 hours before receipt of study intervention. - investigator site staff or pfizer employees directly involved in the conduct of the study, site staff otherwise supervised by the investigator, and their respective family members.

- other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk of study participation or, in the investigator's judgment, make the participant inappropriate for the study. - phases 1 and 2 only: known infection with human immunodeficiency virus (hiv), hepatitis c virus (hcv), or hepatitis b virus (hbv). - history of severe adverse reaction associated with a vaccine and/or severe allergic reaction (eg, anaphylaxis) to any component of the study intervention(s). - receipt of medications intended to prevent covid 19. - previous clinical (based on covid-19 symptoms/signs alone, if a sars-cov-2 naat result was not available) or microbiological (based on covid-19 symptoms/signs and a positive sars-cov-2 naat result) diagnosis of covid 19 - phase 1 only: individuals at high risk for severe covid-19, including those with any of the following risk factors: - hypertension - diabetes mellitus - chronic pulmonary disease - asthma - current vaping or smoking - history of chronic smoking within the prior year - bmi >30 kg/m2 - anticipating the need for immunosuppressive treatment within the next 6 months - phase 1 only: individuals currently working in occupations with high risk of exposure to sars-cov-2 (eg, healthcare worker, emergency response personnel). - immunocompromised individuals with known or suspected immunodeficiency, as determined by history and/or laboratory/physical examination. - phase 1 only: individuals with a history of autoimmune disease or an active autoimmune disease requiring therapeutic intervention. - bleeding diathesis or condition associated with prolonged bleeding that would, in the opinion of the investigator, contraindicate intramuscular injection. - women who are pregnant or breastfeeding. - previous vaccination with any coronavirus vaccine. - individuals who receive treatment with immunosuppressive therapy, including cytotoxic agents or systemic corticosteroids, eg, for cancer or an autoimmune disease, or planned receipt throughout the study. - phase 1 only: regular receipt of inhaled/nebulized corticosteroids. - receipt of blood/plasma products or immunoglobulin, from 60 days before study intervention administration or planned receipt throughout the study. - participation in other studies involving study intervention within 28 days prior to study entry through and including 6 months after the last dose of study intervention, with the exception of interventional studies for prevention of covid 19, which are prohibited throughout study participation. - previous participation in other studies involving study intervention containing lipid nanoparticles. - phase 1 only: positive serological test for sars-cov-2 igm and/or igg antibodies at the screening visit. - phase 1 only: any screening hematology and/or blood chemistry laboratory value that meets the definition of a ≥ grade 1 abnormality. - phase 1 only: positive test for hiv, hepatitis b surface antigen (hbsag), hepatitis b core antibodies (hbc abs), or hepatitis c virus antibodies (hcv abs) at the screening visit. - phase 1 only: sars-cov-2 naat-positive nasal swab within 24 hours before receipt of study intervention. - investigator site staff or pfizer employees directly involved in the conduct of the study, site staff otherwise supervised by the investigator, and their respective family members.

- other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk of study participation or, in the investigator's judgment, make the participant inappropriate for the study. - phases 1 and 2 only: known infection with human immunodeficiency virus (hiv), hepatitis c virus (hcv), or hepatitis b virus (hbv). - history of severe adverse reaction associated with a vaccine and/or severe allergic reaction (eg, anaphylaxis) to any component of the study intervention(s). - receipt of medications intended to prevent covid 19. - previous clinical (based on covid-19 symptoms/signs alone, if a sars-cov-2 naat result was not available) or microbiological (based on covid-19 symptoms/signs and a positive sars-cov-2 naat result) diagnosis of covid 19 - phase 1 only: individuals at high risk for severe covid-19, including those with any of the following risk factors: - hypertension - diabetes mellitus - chronic pulmonary disease - asthma - current vaping or smoking - history of chronic smoking within the prior year - bmi >30 kg/m2 - anticipating the need for immunosuppressive treatment within the next 6 months - phase 1 only: individuals currently working in occupations with high risk of exposure to sars-cov-2 (eg, healthcare worker, emergency response personnel). - immunocompromised individuals with known or suspected immunodeficiency, as determined by history and/or laboratory/physical examination. - phase 1 only: individuals with a history of autoimmune disease or an active autoimmune disease requiring therapeutic intervention. - bleeding diathesis or condition associated with prolonged bleeding that would, in the opinion of the investigator, contraindicate intramuscular injection. - women who are pregnant or breastfeeding. - previous vaccination with any coronavirus vaccine. - individuals who receive treatment with immunosuppressive therapy, including cytotoxic agents or systemic corticosteroids, eg, for cancer or an autoimmune disease, or planned receipt throughout the study. - phase 1 only: regular receipt of inhaled/nebulized corticosteroids. - receipt of blood/plasma products or immunoglobulin, from 60 days before study intervention administration or planned receipt throughout the study. - participation in other studies involving study intervention within 28 days prior to study entry through and including 6 months after the last dose of study intervention, with the exception of interventional studies for prevention of covid 19, which are prohibited throughout study participation. - previous participation in other studies involving study intervention containing lipid nanoparticles. - phase 1 only: positive serological test for sars-cov-2 igm and/or igg antibodies at the screening visit. - phase 1 only: any screening hematology and/or blood chemistry laboratory value that meets the definition of a ≥ grade 1 abnormality. - phase 1 only: positive test for hiv, hepatitis b surface antigen (hbsag), hepatitis b core antibodies (hbc abs), or hepatitis c virus antibodies (hcv abs) at the screening visit. - phase 1 only: sars-cov-2 naat-positive nasal swab within 24 hours before receipt of study intervention. - investigator site staff or pfizer employees directly involved in the conduct of the study, site staff otherwise supervised by the investigator, and their respective family members.

- other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk of study participation or, in the investigator's judgment, make the participant inappropriate for the study. - phases 1 and 2 only: known infection with human immunodeficiency virus (hiv), hepatitis c virus (hcv), or hepatitis b virus (hbv). - history of severe adverse reaction associated with a vaccine and/or severe allergic reaction (eg, anaphylaxis) to any component of the study intervention(s). - receipt of medications intended to prevent covid 19. - previous clinical (based on covid-19 symptoms/signs alone, if a sars-cov-2 naat result was not available) or microbiological (based on covid-19 symptoms/signs and a positive sars-cov-2 naat result) diagnosis of covid 19 - phase 1 only: individuals at high risk for severe covid-19, including those with any of the following risk factors: - hypertension - diabetes mellitus - chronic pulmonary disease - asthma - current vaping or smoking - history of chronic smoking within the prior year - bmi >30 kg/m2 - anticipating the need for immunosuppressive treatment within the next 6 months - phase 1 only: individuals currently working in occupations with high risk of exposure to sars-cov-2 (eg, healthcare worker, emergency response personnel). - immunocompromised individuals with known or suspected immunodeficiency, as determined by history and/or laboratory/physical examination. - phase 1 only: individuals with a history of autoimmune disease or an active autoimmune disease requiring therapeutic intervention. - bleeding diathesis or condition associated with prolonged bleeding that would, in the opinion of the investigator, contraindicate intramuscular injection. - women who are pregnant or breastfeeding. - previous vaccination with any coronavirus vaccine. - individuals who receive treatment with immunosuppressive therapy, including cytotoxic agents or systemic corticosteroids, eg, for cancer or an autoimmune disease, or planned receipt throughout the study. - phase 1 only: regular receipt of inhaled/nebulized corticosteroids. - receipt of blood/plasma products or immunoglobulin, from 60 days before study intervention administration or planned receipt throughout the study. - participation in other studies involving study intervention within 28 days prior to study entry and/or during study participation. - previous participation in other studies involving study intervention containing lipid nanoparticles. - phase 1 only: positive serological test for sars-cov-2 igm and/or igg antibodies at the screening visit. - phase 1 only: any screening hematology and/or blood chemistry laboratory value that meets the definition of a ≥ grade 1 abnormality. - phase 1 only: positive test for hiv, hepatitis b surface antigen (hbsag), hepatitis b core antibodies (hbc abs), or hepatitis c virus antibodies (hcv abs) at the screening visit. - phase 1 only: sars-cov-2 naat-positive nasal swab within 24 hours before receipt of study intervention. - investigator site staff or pfizer employees directly involved in the conduct of the study, site staff otherwise supervised by the investigator, and their respective family members.

- other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk of study participation or, in the investigator's judgment, make the participant inappropriate for the study. - phases 1 and 2 only: known infection with human immunodeficiency virus (hiv), hepatitis c virus (hcv), or hepatitis b virus (hbv). - history of severe adverse reaction associated with a vaccine and/or severe allergic reaction (eg, anaphylaxis) to any component of the study intervention(s). - receipt of medications intended to prevent covid 19. - previous clinical (based on covid-19 symptoms/signs alone, if a sars-cov-2 naat result was not available) or microbiological (based on covid-19 symptoms/signs and a positive sars-cov-2 naat result) diagnosis of covid 19 - phase 1 only: individuals at high risk for severe covid-19, including those with any of the following risk factors: - hypertension - diabetes mellitus - chronic pulmonary disease - asthma - current vaping or smoking - history of chronic smoking within the prior year - bmi >30 kg/m2 - anticipating the need for immunosuppressive treatment within the next 6 months - phase 1 only: individuals currently working in occupations with high risk of exposure to sars-cov-2 (eg, healthcare worker, emergency response personnel). - immunocompromised individuals with known or suspected immunodeficiency, as determined by history and/or laboratory/physical examination. - phase 1 only: individuals with a history of autoimmune disease or an active autoimmune disease requiring therapeutic intervention. - bleeding diathesis or condition associated with prolonged bleeding that would, in the opinion of the investigator, contraindicate intramuscular injection. - women who are pregnant or breastfeeding. - previous vaccination with any coronavirus vaccine. - individuals who receive treatment with immunosuppressive therapy, including cytotoxic agents or systemic corticosteroids, eg, for cancer or an autoimmune disease, or planned receipt throughout the study. - phase 1 only: regular receipt of inhaled/nebulized corticosteroids. - receipt of blood/plasma products or immunoglobulin, from 60 days before study intervention administration or planned receipt throughout the study. - participation in other studies involving study intervention within 28 days prior to study entry and/or during study participation. - previous participation in other studies involving study intervention containing lipid nanoparticles. - phase 1 only: positive serological test for sars-cov-2 igm and/or igg antibodies at the screening visit. - phase 1 only: any screening hematology and/or blood chemistry laboratory value that meets the definition of a ≥ grade 1 abnormality. - phase 1 only: positive test for hiv, hepatitis b surface antigen (hbsag), hepatitis b core antibodies (hbc abs), or hepatitis c virus antibodies (hcv abs) at the screening visit. - phase 1 only: sars-cov-2 naat-positive nasal swab within 24 hours before receipt of study intervention. - investigator site staff or pfizer employees directly involved in the conduct of the study, site staff otherwise supervised by the investigator, and their respective family members.

- other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk of study participation or, in the investigator's judgment, make the participant inappropriate for the study. - phases 1 and 2 only: known infection with human immunodeficiency virus (hiv), hepatitis c virus (hcv), or hepatitis b virus (hbv). - history of severe adverse reaction associated with a vaccine and/or severe allergic reaction (eg, anaphylaxis) to any component of the study intervention(s). - receipt of medications intended to prevent covid 19. - previous clinical or microbiological diagnosis of covid 19. - phase 1 only: individuals at high risk for severe covid-19, including those with any of the following risk factors: - hypertension - diabetes mellitus - chronic pulmonary disease - asthma - current vaping or smoking - history of chronic smoking within the prior year - bmi >30 kg/m2 - anticipating the need for immunosuppressive treatment within the next 6 months - phase 1 only: individuals currently working in occupations with high risk of exposure to sars-cov-2 (eg, healthcare worker, emergency response personnel). - immunocompromised individuals with known or suspected immunodeficiency, as determined by history and/or laboratory/physical examination. - phase 1 only: individuals with a history of autoimmune disease or an active autoimmune disease requiring therapeutic intervention. - bleeding diathesis or condition associated with prolonged bleeding that would, in the opinion of the investigator, contraindicate intramuscular injection. - women who are pregnant or breastfeeding. - previous vaccination with any coronavirus vaccine. - individuals who receive treatment with immunosuppressive therapy, including cytotoxic agents or systemic corticosteroids, eg, for cancer or an autoimmune disease, or planned receipt throughout the study. - phase 1 only: regular receipt of inhaled/nebulized corticosteroids. - receipt of blood/plasma products or immunoglobulin, from 60 days before study intervention administration or planned receipt throughout the study. - participation in other studies involving study intervention within 28 days prior to study entry and/or during study participation. - previous participation in other studies involving study intervention containing lipid nanoparticles. - phase 1 only: positive serological test for sars-cov-2 igm and/or igg antibodies at the screening visit. - phase 1 only: any screening hematology and/or blood chemistry laboratory value that meets the definition of a ≥ grade 1 abnormality. - phase 1 only: positive test for hiv, hepatitis b surface antigen (hbsag), hepatitis b core antibodies (hbc abs), or hepatitis c virus antibodies (hcv abs) at the screening visit. - phase 1 only: sars-cov-2 naat-positive nasal swab within 24 hours before receipt of study intervention. - investigator site staff or pfizer employees directly involved in the conduct of the study, site staff otherwise supervised by the investigator, and their respective family members.

- other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk of study participation or, in the investigator's judgment, make the participant inappropriate for the study. - phases 1 and 2 only: known infection with human immunodeficiency virus (hiv), hepatitis c virus (hcv), or hepatitis b virus (hbv). - history of severe adverse reaction associated with a vaccine and/or severe allergic reaction (eg, anaphylaxis) to any component of the study intervention(s). - receipt of medications intended to prevent covid 19. - previous clinical or microbiological diagnosis of covid 19. - phase 1 only: individuals at high risk for severe covid-19, including those with any of the following risk factors: - hypertension - diabetes mellitus - chronic pulmonary disease - asthma - current vaping or smoking - history of chronic smoking within the prior year - bmi >30 kg/m2 - anticipating the need for immunosuppressive treatment within the next 6 months - phase 1 only: individuals currently working in occupations with high risk of exposure to sars-cov-2 (eg, healthcare worker, emergency response personnel). - immunocompromised individuals with known or suspected immunodeficiency, as determined by history and/or laboratory/physical examination. - phase 1 only: individuals with a history of autoimmune disease or an active autoimmune disease requiring therapeutic intervention. - bleeding diathesis or condition associated with prolonged bleeding that would, in the opinion of the investigator, contraindicate intramuscular injection. - women who are pregnant or breastfeeding. - previous vaccination with any coronavirus vaccine. - individuals who receive treatment with immunosuppressive therapy, including cytotoxic agents or systemic corticosteroids, eg, for cancer or an autoimmune disease, or planned receipt throughout the study. - phase 1 only: regular receipt of inhaled/nebulized corticosteroids. - receipt of blood/plasma products or immunoglobulin, from 60 days before study intervention administration or planned receipt throughout the study. - participation in other studies involving study intervention within 28 days prior to study entry and/or during study participation. - previous participation in other studies involving study intervention containing lipid nanoparticles. - phase 1 only: positive serological test for sars-cov-2 igm and/or igg antibodies at the screening visit. - phase 1 only: any screening hematology and/or blood chemistry laboratory value that meets the definition of a ≥ grade 1 abnormality. - phase 1 only: positive test for hiv, hepatitis b surface antigen (hbsag), hepatitis b core antibodies (hbc abs), or hepatitis c virus antibodies (hcv abs) at the screening visit. - phase 1 only: sars-cov-2 naat-positive nasal swab within 24 hours before receipt of study intervention. - investigator site staff or pfizer employees directly involved in the conduct of the study, site staff otherwise supervised by the investigator, and their respective family members.