18 Rubella

18.5 Recommended immunisation schedule

As in other developed countries, New Zealand’s primary strategy for preventing and eventually eliminating rubella is to vaccinate both boys and girls with two doses of MMR. This strategy is backed up by checking the immune status of pregnant, or about to become pregnant, women and some health care and child care workers. Non-immune women can then be offered up to two more doses of vaccine.

It is important for vaccinators to be able to explain why boys need rubella vaccine, given that the aim is to prevent rubella in pregnancy. In New Zealand and the UK, where a targeted approach was used and 11 year-old girls were offered rubella immunisation, even with high coverage there were still women of childbearing age who were susceptible to rubella, either because of failure to be vaccinated or vaccine failure. Rubella continued to circulate in New Zealand because children aged under 11 years and males were not vaccinated, and so CRS continued to occur, albeit at a reduced rate.

To prevent all cases of CRS, rubella must not circulate in the community and therefore males must be immunised. Achieving at least 95 percent coverage of two doses of MMR should prevent the circulation of rubella (which is less infectious than measles) and therefore lead to the elimination of both rubella and CRS.

18.5.1 Children

Two doses of rubella vaccine as MMR are recommended at age 15 months and age 4 years. The second dose is not a booster. Two doses are recommended because the 2–5 percent not protected by the first dose will nearly all be protected by the second. The second dose of vaccine can be given as soon as four weeks after the first dose. (See below for the recommendations for other groups.)

Children who in an outbreak (of measles, mumps or rubella) receive MMR vaccine when aged under 12 months require two further doses administered after age 12 months. MMR vaccine may be given to children aged 12 months or older whose parents/guardians request it, and no opportunity should be missed to achieve immunity.

18.5.2 Women planning pregnancy and pregnant womenTop

It is recommended that women be screened for rubella immunoglobulin G (IgG) antibody when pregnancy is planned (not funded) or in the antenatal period of every pregnancy (funded); see section 18.5.4. This is to provide a baseline level of information in the very rare event of them being exposed during the early part of pregnancy, when the risks and consequences of CRS are greatest. It also indicates a need for vaccination, if non-immune, with two doses of MMR (funded) when not pregnant.

The following groups of women are more likely to be seronegative to rubella:5

CRS is less likely after reinfection with rubella in pregnancy compared with a primary infection. It is estimated that the prevalence of CRS is 85 percent after primary infection of the mother, and 5 percent after reinfection with rubella in the first trimester. The risk of CRS is negligible after 16 weeks of pregnancy.6

Pregnant women with a rubella antibody level below 10 IU/mL (see section 18.5.4) should be advised to avoid situations in early pregnancy where contact with rubella is more likely, such as with overseas travel to countries with endemic disease or known outbreaks. If the antibody level is below 10 IU/mL, the woman should be offered MMR after delivery if she has not already received two doses of a rubella-containing vaccine as an adult (funded).

If MMR vaccine and anti-D immunoglobulin are required after delivery, both the vaccine and anti-D immunoglobulin may be given at the same time, in separate sites with separate syringes. The vaccine may be given at any time after the delivery. Anti-D immunoglobulin does not interfere with the antibody response to the vaccine, but whole blood transfusion does inhibit the response in up to 50 percent of vaccinees. Rubella serology should be checked in women six to eight weeks after MMR vaccination to ensure that seroconversion has occurred; give a single further dose of MMR if it has not. There is no risk to the mother or child in giving MMR to breastfeeding women.1

18.5.3 Other adultsTop

If an individual has no documented history of immunisation with MMR, they should be given two doses of MMR four weeks apart (funded) rather than performing serology. There are no significant adverse effects from vaccinating individuals who are already immune to measles, mumps and/or rubella, and no reliance can be placed on a prior clinical history of rubella infection.

Immigrants to New Zealand

Over 95 percent of individuals will become immune to rubella after two doses of a rubella-containing vaccine. While most developed countries have for many years included rubella vaccination on their immunisation schedules, this has not been the case for low- and middle-income countries such as those in the Pacific Islands, although these countries may have had single-antigen measles vaccine. Surveys of susceptibility to rubella in women of childbearing age have found rates greater than 25 percent in India, Israel, Malaysia, Nigeria, Singapore, Sri Lanka and Thailand, and rates of 10–25 percent in many African, Middle Eastern and South American countries.

The vaccination status of immigrants should be checked as a priority group. Anyone who does not have two documented doses of MMR vaccine, given any time after age 1 year, should be offered either one or two doses (four weeks apart) to bring them up to two doses (funded if eligible). Even if the individual has previously received single-antigen measles vaccine, up to two doses of MMR vaccine (ie, additional doses of measles vaccine) may be given to these individuals.

Health care workers and students

Health care workers and students without a documented history of two doses of MMR vaccine or documented rubella antibody IgG (see section 18.5.4) are recommended (and funded) to receive two doses of MMR vaccine (four weeks apart), which are needed to provide protection against the three diseases.

18.5.4 Immunity testing and interpretationTop

A person is considered to be immune to rubella if he or she has received two documented doses of MMR, or their immunity is proven through serological testing as an adult. (Routine serological testing of children after vaccination is not indicated.)

In general, it should be remembered that the great majority of New Zealand-born individuals who received all scheduled childhood vaccines will be immune to rubella, and the chance of being exposed in New Zealand to an infectious case is becoming increasingly rare.

Serological testing is not usually performed except as part of routine antenatal care (funded) or for women who are planning pregnancy (not funded). Where serological testing has been performed, the following guidelines apply.

The WHO consider that rubella IgG antibody levels of 10 IU/mL or higher provide evidence of immunity.7 However, licensed assays do not always give consistent results between 5 and 10 IU/mL, the equivocal range. They can reliably detect immunity from past infection, but post-vaccination immunity is harder to measure reliably.8 The previous edition of the Handbook recommended 15 IU/mL as providing a margin of error for the determination of protection, but in line with Australian and other recommendations we now recommend following the testing laboratory’s interpretative comments.

If a person is found to be rubella IgG seronegative, vaccination should be offered according to the recommendations above. Those with equivocal results should be reassured that they are probably protected, but it would be wise to offer revaccination with up to two doses to obtain IgG levels above 10, preferably 20, IU/mL.

18.5.5 ImmunosuppressionTop

MMR vaccine is contraindicated in immunosuppressed children (see section 11.5.3 for more information). Upon specialist advice, MMR vaccine may be given to children with HIV infection who are asymptomatic and who are not severely immune compromised (see also the HIV discussion in section 4.3.3).

MMR vaccine is funded for (re-)vaccination following immunosuppression. However, this first must be discussed with the individual’s specialist.