Inclusion Criteria

1. 18-79 years old

2. Have a history of any of the following risk factors for severe COVID:

- Asthma

- Physical inactivity (defined as <150 mins of moderate activity per week or <75
mins of vigorous activity per week)

- HIV with CD4 count ≥ 500 cells/ul

- Current or prior smoker

- Depression or other mood disorder

- Schizophrenia spectrum disorder

- Cerebrovascular disease

- Heart failure

- Coronary artery disease

- Cardiomyopathy

- Pulmonary embolism

- Pulmonary hypertension

- Cystic fibrosis

- Bronchiectasis

- Chronic obstructive pulmonary disease

- Interstitial Lung Disease

- Stage I or II chronic kidney disease

- Stage 1 defined as normal GFR (> 90) but with other signs of kidney damage such
as proteinuria or hematuria

- Stage 2 defined as having a glomerular filtration rate (GFR) of 60 - 89
ml/min/1.73m2

- Gestational diabetes

- Type 1 diabetes with most recent HgbA1C < 7.5%

- Type 2 diabetes with most recent HgbA1C < 7.5%

- Obesity with BMI ≥ 30 and < 40

- Liver disease without cirrhosis and with liver enzyme levels

- (AST and ALT) no greater than three times the upper limit of normal

3. Military Health System beneficiary and DEERS eligible

4. Willing to be randomized to receive either the Novavax COVID-19 vaccine or the mRNA
Pfizer-BioNTech COVID-19 vaccine

5. Will be able to return for a clinic visit in approximately 30 days and be able to
follow-up online for the next 9 months.

Exclusion Criteria

1. History of severe allergy or severe adverse reaction such as myocardial inflammation
to any component of the mRNA COVID-19 vaccines or the Novavax recombinant COVID-19
vaccine

2. Received a COVID-19 vaccine in the last 3 months.

3. Tested positive for COVID-19 in the past 3 months.

- Presence of fever, cough, chills, shortness of breath, runny nose, or sore throat
today on day of screening/enrollment visit.

4. Active use of immune modulating medications.

- Defined as active use of chronic immune modulating medications such as systemic
corticosteroids at a dose equivalence of 20 mg prednisone or greater daily for over
one month, chemotherapy, cytokine inhibitors, or agents that reduce T cell or B cell
numbers or function.

5. Diagnosed with immunocompromised stated.

- Defined as: presence of a disease that is actively causing severe immune
suppression or history of prior splenectomy (removal of spleen).

6. Diabetes with the most recent HgbA1C ≥ 7.5.

7. Stage III or greater chronic kidney disease

- Defined as estimated glomerular filtration rate < 60 ml/min/1.73m2)

8. Obesity with a BMI ≥ 40

9. HIV with a CD4 cell count < 500 cells/ul

10. History of solid organ or bone marrow transplant.

11. Active malignancy

- Defined as any cancer that is currently being treated or has shown evidence of
progression within the past year.

12. Chronic liver disease with compensated or decompensated cirrhosis, or liver enzyme
levels (AST or ALT) greater than three times the upper limit of normal.