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- - - SAGE REPORT: RUBELLA VACCINATION POLICY/ POLIO ERADICATION

Monday, 11th of March 2013

The complete report, in French and English, is at http://www.who.int/wer/2011/wer8621.pdf

 

SAGE REPORT: RUBELLA VACCINATION POLICY/ POLIO ERADICATION

Rubella vaccination

SAGE reviewed the report from the working group on Rubella summarizing information on rubella vaccine

characteristics, the global burden of congenital rubella

syndrome (CRS), and country and regional experiences

with use of rubella vaccines. This information formed

the basis for formulating recommendations on possible

goals and strategies for rubella/CRS prevention. In addition,

2 disease modeling approaches were used to

determine the minimum routine immunization coverage

that should be achieved and maintained to ensure

that the introduction of rubella-containing vaccine

(RCV) into the routine childhood immunization schedule

would not increase the risk of CRS.

Since 2000 when the rubella position paper was published,

31 additional countries have introduced RCV

into their national childhood immunization programmes.

Goals for the regional elimination of rubella

have been established in the Region of the Americas by

2010 and the European Region by 2015, and the Western

Pacific Region has established a target for accelerated

rubella control and CRS prevention by 2015. Despite this

progress, a recent study estimated that 112 000 infants

are born with CRS each year (uncertainty estimate:

16 000–288 000). The Regions with the highest burden

of CRS are the African and South-East Asian Regions

where RCV uptake remains low. All of the remaining

63 countries that have not yet introduced rubella vaccine

are providing two doses of measles vaccine through

a combination of routine immunization and SIAs as

part of accelerated measles mortality reduction or regional

elimination efforts. These measles vaccine delivery

strategies provide an opportunity for synergy

and a platform for advancing rubella and CRS elimination

through use of combined measles-rubella vaccine.

Field studies of the most widely used rubella vaccine

(RA 27/3 strain) have found vaccine effectiveness of

>95% following one dose and long lasting duration of

protection spanning at least 10–21 years. RCV vaccine

is usually administered at age 12–15 months but can

also be administered to children as young as 9 months

of age. Because of these vaccine characteristics and the

moderate infectiousness of rubella (herd immunity

threshold of 83%–85%), only one dose of RCV is required

to achieve rubella elimination if high coverage

is achieved. However, when combined with measles vaccination,

it may be programmatically easier to provide

a second dose of RCV using the same combined measles-

rubella (MR) vaccine or measles-mumps-rubella

(MMR) vaccine for both doses. Rubella vaccination

should be avoided during pregnancy because of the

theoretical, but yet undemonstrated, teratogenic risk. No

cases of CRS have been reported in more than 2770 susceptible

women who were unknowingly pregnant and

received RCV in early pregnancy. However, women

should provide a negative pregnancy history prior to

vaccination and be advised to avoid pregnancy for one

month after vaccination, although there is no need to

screen using pregnancy tests. Rubella vaccination

during pregnancy is not an indication for abortion.

The primary purpose of rubella vaccination is to prevent

the occurrence of congenital rubella infection including

CRS. There are two general approaches to using

rubella vaccine. The first focuses exclusively on CRS reduction

through immunization of adolescent girls and/

or women of childbearing age (WCBA). The second

approach is comprehensive, focusing on interrupting

rubella virus transmission, thereby eliminating rubella

as well as CRS. The latter approach requires introduction

of RCV in the routine childhood immunization

schedule combined with vaccination of older age groups

who are susceptible to rubella. Depending on the burden

of disease and available resources, countries may

choose to accelerate their progress towards elimination

by conducting wide age range campaigns targeting both

males and females.

Countries planning to introduce RCV should review the

epidemiology of rubella, assess the burden CRS, and

establish rubella/CRS prevention as a public health priority.

Depending on the burden of CRS and available

resources, countries should determine their goal and

time frame for achieving it. Introduction of RCV implies

a long-term commitment to achieving and maintaining

sufficient immunization coverage to ensure sustained

reduction in CRS incidence. Strong political commitment

to the elimination of rubella and CRS, and sustainable

financing for vaccination and surveillance

activities must be in place before initiating rubella

vaccination.

Field and laboratory surveillance for rubella should be

fully integrated with measles in a single surveillance

system. The need to document the impact of rubella

vaccination requires laboratory-supported surveillance

for rubella, CRS surveillance, molecular epidemiology,

and monitoring of vaccine coverage and population

immunity using seroprevalence surveys where appropriate.

Considering the substantial remaining burden of CRS,

SAGE recommends that countries should take the opportunity

of the 2-dose measles vaccine strategy to use

MR or MMR vaccine. Sustained low rubella immunization

coverage in infants and young children (for ex-

ample, when rubella vaccine is used in the private sector

alone) will result in an increase in susceptibility

among WCBA that may increase the risk of CRS (paradoxical

effect). However, if vaccination coverage is sufficiently

high, rubella transmission will be markedly

reduced or interrupted, thereby removing the risk of

rubella exposure for pregnant women.

SAGE recommends that countries introducing RCV

should achieve and maintain immunization coverage of

at least 80% with RCV delivered through routine services

and/or regular SIAs. The preferred approach is to

begin with MR vaccine or MMR vaccine in a wide age

range campaign followed immediately by introduction

of MR vaccine in the routine programme. The first dose

of MR vaccine can be delivered at 9 months or 12 months

of age depending on the level of measles virus transmission.

6 All subsequent follow-up campaigns should use

MR vaccine or MMR vaccine.

For countries undertaking the strategy of CRS reduction

alone, adolescent and adult females should be vaccinated

through either routine services or SIAs. This option

will provide direct protection to WCBA; however,

the impact of this strategy is limited by the coverage

achieved and the age groups targeted. In the absence of

a programme that vaccinates infants and young children,

rubella continues to circulate resulting in ongoing

exposure of pregnant women and the associated risk of

CRS.

Polio eradication

The Chair of the newly established Independent Monitoring

Board (IMB) for the Global Polio Eradication

Initiative (GPEI) provided SAGE with a brief report of

the first 2 IMB meetings. He outlined the terms of reference

and expected work methods of the IMB, and briefly

commented on the current assessment of the global

polio situation, particularly in the 4 endemic countries

and countries with re-established transmission, in relation

to tracking the milestones of the GPEI Strategic

Plan 2010–2012.

SAGE noted that the IMB’s focus will be on monitoring

global milestones, and that to optimize the benefit for

the GPEI, SAGE would be willing to play a more substantive

role in providing technical and strategic guidance

to the GPEI in the eradication phase, in addition

to the role it already plays in considering post-eradication

issues.

In terms of post-eradication policy development, SAGE

appreciated the report on recent advances towards affordable

IPV options for low-income countries during

the post-eradication era, particularly the results of recent

trials conducted in Cuba and Oman comparing

fractional IPV doses given intradermally with full doses

given intramuscularly. Seroconversion achieved in the

Cuban trial after the first dose of fractional and fulldose

IPV ranged from 15.1% (intradermal administration

and for type 3 poliovirus) to 63.6% (intramuscular

administration and for type 2 poliovirus), with both ap-

proaches showing clear evidence of priming in >90%

of subjects who had not seroconverted after the first

dose. With both approaches very high (>95%) seroconversion

rates were achieved after 2 doses spaced

4 months apart. SAGE strongly encouraged the GPEI to

procede with its full IPV research agenda, in particular

to clarify the duration and quality of the priming immune

response to inform the work of the SAGE IPV

working group.

The main focus of the third meeting of the SAGE IPV

working group was the feasibility and potential prerequisites

for switching from oral poliovirus vaccines containing

a type-2 component (i.e. trivalent OPV, tOPV) to

vaccines containing only types 1 and 3 (bivalent OPV,

bOPV) for routine immunization in advance of global

certification of eradication of all 3 serotypes. The rationale

for considering a shift was the continued polio

paralysis due to type-2 component (VAPP) and circulating

vaccine-derived type 2 poliovirus (cVDPV2), despite

eradication of wild poliovirus type 2. While recognizing

this rationale, SAGE expressed concern that the issue of

switching from tOPV to bOPV should not distract from

pursuing the goal of wild virus eradication, and requested

that the perspective of the African and Eastern

Mediterranean Regions be sought. SAGE agreed that

over the next 12 months the programme should further

assess the prerequisites, risks and benefits, feasibility

and programmatic implications of this switch. This assessment

must include dialogue with vaccine manufacturers,

particularly on the implications of restarting

tOPV production should that be required. Consideration

should be given to linking any decisions on the timing

of such a switch to the achievement of key polio eradication

milestones to minimize any potential risk to

wild poliovirus eradication efforts.

SAGE noted that the working group had revisited the

issue of post-eradication IPV policy in low-income settings

in the light of the new information on affordable

IPV options and agreed that the group should now focus

on further clarifying the criteria for IPV use (e.g.

coverage and cVDPV risk) and the modalities of use

(e.g. schedules and vaccine formulations) in the posteradication

era.