inclusion criteria: 1. diagnosis of clinically definite multiple sclerosis (cdms) by the 2017 mcdonald criteria 38; 2. age greater than or equal to 18 years; 3. ability to travel to griffin hospital for phlebotomy and booster vaccination; 4. completion of an initial covid-19 vaccine series at least 4 weeks prior to booster randomization (i.e., two doses of either bnt162b2 or mrna-1273, or one dose of ad26.cov2.s); 5. prior negative test for covid-19 spike protein antibodies using a commercial assay; 6. willing to undergo a booster vaccination with either bnt162b2, mrna-1273 or ad26.cov2.s.

inclusion criteria: 1. diagnosis of clinically definite multiple sclerosis (cdms) by the 2017 mcdonald criteria 38; 2. age greater than or equal to 18 years; 3. ability to travel to griffin hospital for phlebotomy and booster vaccination; 4. completion of an initial covid-19 vaccine series at least 4 weeks prior to booster randomization (i.e., two doses of either bnt162b2 or mrna-1273, or one dose of ad26.cov2.s); 5. prior negative test for covid-19 spike protein antibodies using a commercial assay; 6. willing to undergo a booster vaccination with either bnt162b2, mrna-1273 or ad26.cov2.s.

inclusion criteria: diagnosis of clinically definite multiple sclerosis (cdms) by the 2017 mcdonald criteria 38; age greater than or equal to 18 years; ability to travel to griffin hospital for phlebotomy and booster vaccination; completion of an initial covid-19 vaccine series at least 4 weeks prior to booster randomization (i.e., two doses of either bnt162b2 or mrna-1273, or one dose of ad26.cov2.s); prior negative test for covid-19 spike protein antibodies using a commercial assay; willing to undergo a booster vaccination with either bnt162b2, mrna-1273 or ad26.cov2.s.

inclusion criteria: diagnosis of clinically definite multiple sclerosis (cdms) by the 2017 mcdonald criteria 38; age greater than or equal to 18 years; ability to travel to griffin hospital for phlebotomy and booster vaccination; completion of an initial covid-19 vaccine series at least 4 weeks prior to booster randomization (i.e., two doses of either bnt162b2 or mrna-1273, or one dose of ad26.cov2.s); prior negative test for covid-19 spike protein antibodies using a commercial assay; willing to undergo a booster vaccination with either bnt162b2, mrna-1273 or ad26.cov2.s.

inclusion criteria: diagnosis of clinically definite multiple sclerosis (cdms) by the 2017 mcdonald criteria 38; age greater than or equal to 18 years; ability to travel to griffin hospital for phlebotomyand booster vaccination; completion of a covid-19 vaccine series at least 4 weeks prior to booster randomization; willing to undergo a booster vaccination with either bnt162b2, mrna-1273 or ad26.cov2.s.

inclusion criteria: diagnosis of clinically definite multiple sclerosis (cdms) by the 2017 mcdonald criteria 38; age greater than or equal to 18 years; ability to travel to griffin hospital for phlebotomyand booster vaccination; completion of a covid-19 vaccine series at least 4 weeks prior to booster randomization; willing to undergo a booster vaccination with either bnt162b2, mrna-1273 or ad26.cov2.s.

inclusion criteria: 1. diagnosis of clinically definite multiple sclerosis (cdms) by the 2017 mcdonald criteria 38; 2. age greater than or equal to 18 years; 3. ability to travel to griffin hospital for phlebotomyand booster vaccination; 4. completion of a covid-19 vaccine series at least 4 weeks prior to booster randomization; 5. willing to undergo a booster vaccination with either bnt162b2, mrna-1273 or ad26.cov2.s.

inclusion criteria: 1. diagnosis of clinically definite multiple sclerosis (cdms) by the 2017 mcdonald criteria 38; 2. age greater than or equal to 18 years; 3. ability to travel to griffin hospital for phlebotomyand booster vaccination; 4. completion of a covid-19 vaccine series at least 4 weeks prior to booster randomization; 5. willing to undergo a booster vaccination with either bnt162b2, mrna-1273 or ad26.cov2.s.