GPs should give women over 20 weeks pregnant, who have never had chickenpox, the ‘off-label’ anti-viral drug aciclovir if they have been exposed to the virus, Public Health England has said.
PHE advised GPs, obstetricians and midwives to only offer the standard chickpox vaccine to susceptible pregnant woman who have had ‘significant exposure’ to shingles or chickenpox in the first 20 weeks of pregnancy.
The advice comes in response to a ‘significant national shortage’ of varicella zoster immunoglobulin (VZIG) which started last month as a result of manufacturing issues.
In a report, PHE said that during this rationing period, pregnant women who are exposed after 20 weeks should be offered the oral anti-viral drug, aciclovir at 800mg, four times a day from day seven to 14 after exposure.
This is despite the drug not being licenced in pregnant women.
PHE said: ‘As oral aciclovir and valaciclovir are not licensed for use in pregnancy, their use for women exposed after 20 weeks would be ‘off label’.’
It added: ‘Oral aciclovir is not licensed in pregnancy but there is extensive evidence for safety of use in pregnancy, including from two large registries of infants whose mothers were exposed to aciclovir in pregnancy.’
But the report added: ‘There are no changes to the guidance for immunosuppressed patients or neonates.’
The advice has been agreed by PHE experts and the chair of the Joint Committee on Vaccination and Immunisation varicella subcommittee, an independent body that advises UK health departments on immunisation, after considering what was in the best interest of the patient.
PHE said the change is likely to ‘affect a very small proportion of the antenatal population’ due to the majority of adults being immune to chickenpox, but that it would keep the situation ‘under constant review’, with this new guidance in place ‘until further notice’.
PHE has already asked GPs to boost pertussis vaccine uptake in pregnant women following a rise in the number of whooping cough cases.