Inclusion Criteria

- Female (ages 18-45 years) or Male (ages 18-60 years)

- Normal blood pressure (systolic BP < 140 mm Hg, diastolic < 90 mm Hg)

- Hemoglobin no less than 0.5 g/dL below the lower limit of the sex specific reference
range

- No current or recent use of a medication (including hormonal replacement) that, in
the opinion of a study investigator, can modulate the reproductive axis or willing
to complete an appropriate washout for that particular medication and its method of
administration

- For women, negative serum hCG pregnancy test

- For cases, diagnosis of post-covid-19 syndrome

- For controls, history of prior covid infection but no diagnosis of post-covid-19
syndrome

Exclusion Criteria

- Any condition (medical, mental, or behavioral) that, in the opinion of a study
investigator, would likely interfere with participation in/completion of the
protocol

- Excessive alcohol consumption (>10 drinks/week)

- Active use of illicit drugs

- For women,

- Pregnant

- Trying to become pregnant during protocol participation

- Breast feeding

- History of any of the following: bilateral oophorectomy (ovaries were removed),
breast cancer, thromboembolic disease, coronary artery disease, stroke,
thrombophilic disorders, or undiagnosed abnormal genital bleeding