Question 1

How does mpox spread compared to smallpox?

Accepted Answer

Smallpox spread almost exclusively person-to-person through respiratory droplets and direct contact with skin lesions, and was highly contagious with a basic reproduction number (R0) of 5-7. Mpox is less transmissible: clade IIb (2022 outbreak) spread primarily through close physical and sexual contact, with an estimated R0 of 1.1-2.4 in the MSM community. Mpox also has a zoonotic reservoir (rodents, primates), meaning it can re-enter the human population from animals — unlike smallpox, which had no animal reservoir.

Question 2

How long does mpox last?

Accepted Answer

Mpox illness typically lasts 2-4 weeks. A prodromal phase of fever, lymphadenopathy, and fatigue precedes the rash by 1-5 days. The rash phase — lesions progressing macule, papule, vesicle, pustule, scab — lasts 2-3 weeks. A person remains infectious from symptom onset until all scabs have fallen off and new skin has healed beneath them. Milder clade IIb cases from the 2022 outbreak (few lesions limited to the genital area) sometimes resolved in under 2 weeks.

Question 3

Is mpox as dangerous as smallpox?

Accepted Answer

No. Mpox is substantially less dangerous than smallpox. Smallpox had a case fatality rate of approximately 30% and caused disfigurement in survivors. Mpox clade II (responsible for the 2022-2024 global outbreak) has a fatality rate below 1% in high-income settings. Mpox clade I, circulating in Central Africa, carries a higher fatality rate of 1-10%, historically higher in children. Smallpox was eradicated globally in 1980; mpox continues to circulate in animal reservoirs and spreads to humans.

Question 4

Is mpox eradicated like smallpox?

Accepted Answer

No. Mpox is not eradicated. Smallpox is the only human disease ever declared eradicated (WHO, 1980), achieved through a global vaccination campaign. Mpox continues to circulate in animal reservoirs (primarily rodents in Central and West Africa) and causes recurrent human outbreaks. The 2022-2024 global mpox outbreak (clade IIb) led the WHO to declare a Public Health Emergency of International Concern (PHEIC) twice: in 2022 and again in August 2024 when clade I expanded in the DRC and neighbouring countries. Eradication of mpox is not currently feasible given its animal reservoir.

Question 5

Is mpox sexually transmitted?

Accepted Answer

Mpox is not classified as a traditional sexually transmitted infection (STI), but sexual contact is an efficient transmission route. During the 2022 clade IIb global outbreak, the majority of cases in high-income countries involved men who have sex with men (MSM), transmitted through close skin-to-skin contact during sex. The virus spreads via direct contact with lesions, rash, or body fluids — circumstances common during sexual activity. However, mpox also transmits through non-sexual close contact (household, healthcare settings), distinguishing it from classic STIs.

Question 6

What treatment is available for mpox?

Accepted Answer

Tecovirimat (TPOXX/ST-246) is an antiviral approved by the FDA and EMA specifically for the treatment of orthopoxvirus infections including mpox. Brincidofovir and cidofovir are alternative antivirals used in severe cases. For most people with clade II mpox, illness is self-limiting and resolves within 2-4 weeks with supportive care (pain management, wound care, hydration). Severe cases — clade I infection, immunocompromised patients, children, or extensive skin involvement — require antiviral treatment and may need hospitalisation.

Question 7

What is the difference between mpox and smallpox?

Accepted Answer

Mpox and smallpox are both caused by orthopoxviruses, but they are distinct diseases. Smallpox (Variola virus) was eradicated in 1980 and no longer occurs naturally. Mpox (Monkeypox virus) is an ongoing zoonotic disease, with outbreaks in 2022-2024 (clade IIb, global) and 2024-2025 (clade I, primarily Democratic Republic of Congo). Key clinical difference: mpox causes prominent lymphadenopathy (swollen lymph nodes), which does NOT occur in smallpox. Mpox is significantly less severe: clade II fatality rate is under 1%, while smallpox killed approximately 30% of those infected.

Question 8

What are the symptoms of mpox vs smallpox?

Accepted Answer

Both diseases begin with fever, headache, back pain, and fatigue, followed by a characteristic rash. The key distinguishing features of mpox are: (1) prominent lymphadenopathy (swollen glands) — absent in smallpox; (2) rash lesions may appear in different stages simultaneously; (3) genital/perianal lesions are common in clade IIb. Smallpox lesions were uniform in stage and deeply embedded in the skin. Mpox lesions evolve through macule, papule, vesicle, pustule, scab, typically over 2-4 weeks. In the 2022 clade IIb outbreak, many cases presented with few lesions limited to the genital area without a classical widespread rash.

Question 9

Is the smallpox vaccine effective against mpox?

Accepted Answer

Yes. Smallpox vaccines provide cross-protection against mpox because both viruses are orthopoxviruses. The JYNNEOS vaccine (MVA-BN, Imvamune/Imvanex) is specifically approved for both mpox and smallpox prevention. ACAM2000 (the replication-competent vaccinia vaccine) is also protective but carries more side-effect risks. Pre-1980 smallpox vaccination campaigns conferred approximately 85% protection against mpox; that immunity has waned in the global population since routine vaccination stopped. JYNNEOS is now recommended as a 2-dose series for at-risk individuals in many countries.

Mpox (viruela símica)

Strains

Transmission

Symptoms

Prodromal phase (days 0–5)

Rash phase — clade I classic presentation (1–5 days after fever onset)

Rash phase — clade IIb mpox rash symptoms (2022–2024 global outbreak pattern)

Complications (severe or immunocompromised cases)

Treatment

Vaccine status

Endemic regions

Frequently asked questions

Compare to other viruses

Mpox vs Smallpox: transmission, rash, mortality and vaccine compared

Sources