Table 1 Characteristics of viral transmission including the particle to plaque forming unit ratio assessed in cell culture and reproductive number assessed in epidemiologic studies

Ebola

(-ssRNA)

511 [12]

1.5–1.9 [21]

2.9 × 10^–3–3.7 × 10^–3

Bodily Fluids

Particle:PFU from strain at Walter Reed Medical Center [1]; R_o from 2014 epidemic [21]

Influenza A*

(-ssRNA)

20–509

0.9–2.1 [6]

4.2 × 10^–2–4.5 × 10^–2

Predominantly Respiratory Droplet

Seasonal strains

Smallpox

(dsDNA)

1–100 [9, 22]

6.87 [23]

1.46 × 10^–1–14.6

Small particle aerosol

R_o from 1967 outbreak smallpox

VZV

(dsDNA)

40000 [14]

10–12 [24]

2.5 × 10^–4–3 × 10^–4

Small particle aerosol; Vertical

R_o pre-vaccine

Adenoviradae

(dsDNA)

20–100 [9]

2.34 [24]

2.3 × 10^–2–1.2 × 10^–1

Fecal–oral; Respiratory

Rotavirus

(dsRNA)

10 [9]

78.8 [26]

7.88

Fecal–oral; Droplet

R_o pre-vaccine estimation

HSV-1*

(dsDNA)

50–200 [9]

2–5 [28]

2 × 10^–2–4 × 10^–2

Bodily Fluids, Sexual, Vertical

P:PFU antecedently recorded as 10:1

HSV-2

(dsDNA)

50–200 [9]

2.07 [29]

1 × 10^–2–4 × 10^–2

Sexual; Vertical

Polio*

(+ ssRNA)

36–1000 [9, 19]

5–6 [24]

6 × 10^–3–1.4 × 10^–1

Fecal–oral

HPV

(dsDNA)

10000 [9]

0.52–1.2 [30]

5.2 × 10^–5–1.2 × 10^–4

Sexual

STI strains; R_o assumes untreated population; ignores autoinnoculation

Coxsackie A

(+ ssRNA)

210 [31]

2.5 [32]

1.2 × 10^–3

Fecal–oral

Measles*

(-ssRNA)

10–200 [16, 17]

12–18 [3]

9 × 10^–2–1.2

Small particle aerosol

R_o pre-vaccine

RSV

(-ssRNA)

3200 [33]

1.2–3.0 [25, 34, 35]

3.8 × 10^–4–9.4 × 10^–4

Respiratory droplet; Fomite

Mumps*

(-ssRNA)

100–1000 [13]

10–12 [24]

1.2 × 10^–2–1 × 10^–1

Respiratory droplet

R_o pre-vaccine

SARS-CoV

(+ ssRNA)

360 [36]

2.2–3.6 [4]

6.1 × 10^–4–1 × 10^–2

Respiratory droplet

Particle:PFU from gRNA

Rhinovirus*

(+ ssRNA)

30–1000 [1, 18]

2–3 [35]

3 × 10^–3–6.7 × 10^–2

Respiratory droplet

Inferred P:PFU; R_o seasonal change

SARS-CoV-2

(+ ssRNA)

1000–1000000 [20, 37]

2.6–5.7 [27]

5.7 × 10^–6–2.6 × 10^–3

Respiratory droplet; possible aerosol

Early studies suggest R_o closer to 2.6