SARS-CoV-2, the highly contagious virus that causes COVID-19, is spread predominantly through respiratory droplets produced when an infected person coughs, sneezes, or talks.38 Symptoms vary widely from mild to severe and include loss of taste or smell, fever, chills, muscle or body aches, sore throat, nausea or vomiting, cough, and breathing difficulties. Symptoms may appear 2-14 days after exposure to the virus; however, some infected patients never develop symptoms and asymptomatic spread is significant.39,40 Infected patients who are older and / or have certain medical conditions (Box 5) are at higher risk of developing severe or fatal disease.41

Box 5. Age and Conditions Associated with Increased COVID Disease Severity41
Age Risk of Hospitalization Risk of Death
 18-29 years  Comparison Group  Comparison Group
 30-39 years  2x higher  4x higher
 40-49 years  3x higher  10x higher
 50-64 years  4x higher  30x higher
 65-74 years  5x higher  90x higher
 75-84 years  8x higher  220x higher
 85+ years   13x higher  630x higher
Conditions associated with increased severity COVID-19
Chronic kidney disease
Chronic obstructive pulmonary disease (COPD)
Down Syndrome
Heart conditions (e.g., heart failure, coronary artery disease, or cardiomyopathies)  
Immunocompromised state from solid organ transplant
Obesity (BMI of 30 - 40)
Severe Obesity (BMI ≥ 40)
Sickle cell disease
Type 2 diabetes mellitus

Active Immunization: SARS-CoV-2.42

The first two COVID-19 vaccines (Pfizer-BioNTech [BNT162b2] and Moderna [mRNA-1273]) developed to prevent SARS-CoV-2 infection received Emergency Use Authorizations from the FDA in December 2020 (Table 7). Both vaccines employ the mRNA technology platform and appear to be very efficacious in generating immunity. BNT162b2 is approved for use in persons ≥12 years of age and mRNA-1273 is approved for persons ≥18 years of age. On February 27, 2021, the FDA issued Emergency Use Authorization of the single-dose COVID -19 vaccine (Johnson & Johnson [JNJ-778436735]). It is an adenovirus serotype 26 vector-based vaccine and is for persons ≥18 years of age. The safety of these vaccines for pregnant and breast-feeding women has not been officially established; however, the American College of Obstetricians and Gynecologists recommend otherwise eligible pregnant or lactating women be vaccinated. Other manufacturers (e.g., AstraZeneca/Oxford, Novavax, others) are aggressively developing additional candidate vaccines.

Table 7. SARS-CoV-2 Vaccines.4,42
 Vaccines  Indications  Schedules Adverse Effects



2 IM doses, 0 and 21 days*

Injection site pain, erythema and swelling, fatigue, axillary swelling / tenderness, fatigue, chills, headache, fever, muscle and joint pain, nausea / vomiting.

Adverse effects more frequent after second dose.

Anaphylaxis and anaphylactoid reactions (~11.1 / million doses) have been reported.


2 IM doses, 0 and 28 days*


 1 IM dose

Injection site pain, erythema and swelling, fatigue, fatigue, headache, myalgia, fever, nausea.

Thrombo-thrombocytopenia syndrome (~3.1 / million doses) and anaphylaxis have been reported.

 * Second doses should be administered as close to the recommended interval as possible. There is no maximum interval between the first and second dose.