The following information has been taken from the Government’s Green Book on smallpox and monkeypox vaccination, the full document can be viewed here.
On this page:
- What vaccination is available?
- Vaccination and pregnancy
- Vaccination and breastfeeding
- Vaccination with an underlying medical condition
- Vaccination and children
- Adverse reactions
What vaccination is available?
In September 2019, the Food and Drug Administration (FDA) in the US approved MVA-BN (Jynneos®) (the US labelled equivalent of Imvanex®) for the prevention of monkeypox as well as smallpox (FDA, 2019). Although not specifically licensed for the prevention of monkeypox in Europe, MVA-BN vaccine has been used in the UK in response to the current and previous incidents.
Following discussions with regional and national experts, we recommend that individuals who are eligible for the vaccine to take up this offer – however, this is a choice for each individual.
To maximise the chance of preventing infection, MVA-BN should preferably be administered within four days from the date of exposure to monkeypox.
Vaccination may still be offered up to 14 days after exposure, with the aim of reducing the symptoms of disease, for those who are not already displaying symptoms. This may be considered in those at higher risk of serious monkeypox infection (children under five years of age, the immunosuppressed and pregnant women). Vaccination up to 14 days after exposure may also be offered to those at on-going risk to commence a pre-exposure course.
Individuals who have previously received a two dose course of MVA-BN, with the second dose given in the past two years, do not need a further dose of vaccine after exposure. The exception is those who are immunosuppressed, who may have made a lower or less durable immune response, when an additional dose can be considered.
Vaccination and pregnancy
Although MVA-BN has not formally been evaluated in pregnancy, animal studies (three studies in female rats) identified no vaccine related fetal malformations. Use of MVA-BN in pregnant women is limited to less than 300 pregnancies without leading to any adverse events on pregnancy.
As it is a non-replicating vaccine, there is no theoretical reason for concerns in pregnancy and the adverse events profile would be expected to be similar to that in non-pregnant vaccinees. Whilst it is not routinely recommended for use in pregnancy, any theoretical concern needs to be weighed against the maternal risks from monkeypox in pregnancy (such as a risk of more severe disease from viral infections in the third trimester) and any consequent fetal risks from maternal infection in early pregnancy.
Vaccination and breastfeeding
It is not known whether MVA-BN is excreted in human milk, but this is unlikely as the vaccine virus does not replicate effectively in humans. Individuals who are breast feeding and have a significant exposure to monkeypox should therefore be offered vaccination, after discussion about the risks of monkeypox to themselves and to the breast-fed child.
Vaccination with an underlying medical condition
Individuals with atopic dermatitis are known to have developed more site-associated reactions and generalized symptoms following MVA-BN vaccination. Individuals in this group therefore need to have a risk assessment before being offered vaccination. The assessment should consider the risk of exposure, the risk of side effects from vaccination and the potential use of alternative preventive interventions.
Vaccination and children
Although the MVA-BN vaccine is not licensed in children, several paediatric studies of other vaccines using MVA as a vector (often at a considerably higher dose than used in MVA-BN) have been undertaken with a reassuring side effect profile. This includes a TB vaccine trial of approximately 1500 infants, aged approximately 5 to 6 months, and a trial of 200 Gambian infants who received an MVA malaria vaccine with an acceptable safety profile (Tameris et al, 2013, Oto et al, 2011, Afolabi et al, 2016).
The adverse event profile with MVA-BN would be expected to be identical to the profile with these TB and malaria candidate vaccines and therefore provides some reassurance of its use in children, including infants. The vaccine should therefore be offered to children considered to be at risk, as children seem to have a more severe presentation of monkeypox.
Adverse reactions
Data from multiple clinical trials shows that MVA-BN has a favourable adverse event profile compared with first and second generation smallpox vaccines (WHO 2013, Frey et al, 2007, Vollmar et al, 2006, von Krempelhuber et al, 2010, Greenberg et al, 2013). Common adverse events include local site reactions and influenza-like symptoms. These events were mainly mild to moderate in intensity and resolved without intervention within seven days following vaccination. Adverse event rates reported after either vaccination dose (1st, 2nd or booster) were similar, but anecdotally the frequency of adverse events, particularly local site reactions, appears to be higher in those who had receive previous live smallpox vaccine.
There have been no reports to date of myocarditis/pericarditis or encephalitis after these vaccines.
Content out of date? Information wrong or not clear enough? Report this page.