Summary :
◉ Monkeypox Vaccine Overview
Monkeypox is a contagious viral disease that occurs mainly in the rainforest regions of Central and West Africa and is sometimes transmitted to other regions.
Faced with the circulation of the Monkeypox virus and the kinetics of the epidemic, a preventive vaccination strategy against monkeypox was proposed to the groups of people most exposed to the virus.
Monkeypox vaccines were originally developed to fight smallpox (smallpox). They were reused due to the genetic similarity between the 2 viruses. Currently, there are 2 vaccines available:
- A third-generation vaccine, marketed by Danish biotech company Bavarian Nordic as Imvanex® in Europe, Jynneos® in the United States and Imvamune® in Canada.
- A second-generation vaccine, ACAM2000, approved for use in the United States under an Expanded Access Investigational New Drug (EA-IND) protocol.
According to CDC : Animal and clinical studies have shown a similar immune response to the JYNNEOS vaccine and the ACAM2000 vaccine.
◉ The monkeypox vaccine regimen
The vaccination schedule includes 2 doses 28 days apart for people aged 18 and over. A third dose 28 days after the second dose is recommended for immunocompromised people.
For children under the age of 18 identified as a risk contact, vaccination will be assessed on a case-by-case basis.
People who received the old smallpox vaccine (used until 1980) only need one dose, or two in case of immunosuppression.
Note: Vaccination does not provide immediate protection, so it is important to continue to avoid risky contact with anyone infected or suspected of having Monkeypox virus.
◉ When can you get vaccinated ?
Vaccine strategies against monkeypox include:
- Post-exposure vaccination: It is recommended that the vaccine be administered within 4 days of the exposure date to prevent the onset of illness. If given between 4 and 14 days after the date of exposure, vaccination may reduce symptoms of disease, but cannot prevent disease.
- Post-exposure revaccination: People who have been exposed to monkeypox virus and have not received the smallpox vaccine within the past 3 years should consider getting vaccinated.
- Pre-exposure prophylaxis: ACIP recommends people whose work may expose them to orthopoxviruses, such as monkeypox, to get vaccinated:
- Clinical laboratory personnel who perform tests to diagnose orthopoxviruses.
- Research laboratory workers who directly handle cultures or animals contaminated or infected with orthopoxviruses.
- Some at-risk members of the healthcare and public health response team.
◉ Who should get vaccinated against monkeypox?
👉 The HAS recommended, in addition to post-exposure vaccination around a confirmed case, extending vaccination to the following target populations:
- Multi-partner men who have sex with men (MSM) and trans people reporting multiple sex partners;
- Sex workers;
- Professionals in places of sexual consumption, regardless of the status of these places.
👉 CDC recommends the vaccine for people who have been exposed to monkeypox or those who are more likely to catch it. This includes:
- If you have been identified as a close contact of someone with monkeypox.
- If you learn that one of your sexual partners in the past 2 weeks has been diagnosed with monkeypox.
- If you are a man who has sex with men or if you are a transgender or gender-diverse person who has sex with men and in the past 2 weeks:
- Have had sex with multiple partners or group sex.
- You had sex in a commercial sex venue (like a sex club or bathhouse).
- Have had sex at an event, place, or area where transmission of monkeypox occurs.
👉 The UK Health Safety Agency (UKHSA) currently recommends that the vaccine be offered to:
- caregivers who manage and need to start managing a patient with confirmed monkeypox (2 doses are normally required). This includes some sexual health clinic staff who assess any suspected cases.
- Gay, bisexual and other men who have sex with men (GBMSM) most at risk of exposure. Your doctor or nurse will advise you to get vaccinated if they consider you to be at high risk - for example if you have multiple partners, engage in group sex or frequent 'sex on the spot' venues. Staff who work in these premises may also be eligible
- people who have had close contact with a confirmed monkeypox patient. Vaccination with a single dose of vaccine should be offered as soon as possible (ideally within 4 days of contact, but can sometimes be given up to 14 days
◉ Mode of administration of the vaccine
The vaccine can be given in three ways :
- If you are 18 or older, you can receive the vaccine in the skin layers of your forearm (0.1 mL intradermally: as IDR tuberculin).
- If you are under 18 or have a history of keloid scarring, you may receive the vaccine in your upper arm, like other vaccines you may have received (0.5 mL per subcutaneous: such as the measles, mumps and rubella (MMR) vaccine).
- For infants under 12 months, it can be given in the thigh like other vaccines they may have had (such as MMR).
◉ Side effects
The most frequently observed side effects:
- Injection site reactions (pain, redness, swelling)
- Muscle pain, pain and swelling at the injection site, fatigue, headache, nausea: very common (>1 case / 10 vaccinated)
- Pain in the extremities, chills, heat at the injection site, slight fever, appetite disturbances
- Rash, cough, diarrhoea, vomiting, dizziness, muscle stiffness, armpit swelling, malaise, chest pain
- Sinusitis, flu, conjunctivitis, migraine, dizziness, muscle weakness, abdominal pain
If you have ACAM200, side effects could include:
- Fever
- Rash
- Swollen lymph nodes
- Myocarditis (swelling of the heart muscle)
- Pericarditis (swelling of sac-like tissue around the heart)
◉ Contraindications
- Have had a severe allergic reaction (anaphylaxis) to chicken or egg protein.
- Have had Stevens-Johnson syndrome.
- To have had toxic epidermal necrolysis.
- Having a high fever, the vaccination should then be postponed
◉ Frequently Asked Questions
Q: Does the smallpox vaccine protect against monkeypox?
A: Previous data from Africa suggest that the smallpox vaccine is at least 85% effective in preventing monkeypox.
Q: Is the IMVANEX vaccine dangerous?
A: IMVANEX can be used safely if you have HIV. It is also safe if you suffer from eczema or other skin conditions, or if you suffer from other conditions that weaken your immune system
Q: vaccination against smallpox in case of pregnancy
A: The CDC states that the JYNNEOS monkeypox vaccine can be offered to pregnant women. However, the organization notes that human data are "insufficient" to determine whether there are any risks to using the vaccine during pregnancy. Vaccination with ACAM2000 is contraindicated in pregnant or breastfeeding persons.
Q: Which company makes the monkeypox vaccine?
A: Bavarian Nordic A/S, the only company with an approved monkeypox vaccine.
