The Joint Committee on Vaccination and Immunisation in the UK has looked at the evidence and recommends that the NHS should start giving infants a chickenpox vaccine. The medical name for chickenpox is herpes varicella.
Chickenpox, once caught, is a lifelong condition, though this is not widely known. The virus lives in each dorsal root ganglion.
Chickenpox virus can recur
When chickenpox recurs, it is called shingles, or herpes zoster. These different names date back to the time before it was known that shingles was a recurrence of chickenpox. There is a vaccine to prevent shingles being given to older people. Shingles pain may occur in older people are it is difficult to treat.
Varivax, the live-attenuated virus vaccine to prevent chickenpox, has been given to children in many countries for many years – since 1995 in the USA. Now it is being recommended in UK too. It will be added to the MMR (mumps measles and rubella) triple vaccine that children already get in two doses at 1 year and then 6 months later.
The new MMRV injection will very slightly increase the risk of an infant having a febrile seizure. In general, during infancy, these relatively common, benign seizures can affect about 1 in 20 infants, who have an illness that causes high fevers. They can have a number of causes. Giving the MMRV raises the risk very slightly, by 1 in 2,300 in comparison with giving the varicella vaccine separately. But overall, the JSVI considers that the acceptability of a single vaccine outweighs this very light increase.
Vaccines are not given to younger babies as they will have maternal antibodies (antibodies passed to the foetus in the womb) to many infections for months after the birth. This protection lasts between 3-6 months, and longer if the infant is breastfed. These antibodies decline progressively over the first year of life. They may interfere with active immunisation before 12 months of age.
Post written 15 November 2023