World health organization regional office for the western pacific regional guidelines

DRAFT of 25 Mar 2004

WORLD HEALTH ORGANIZATION

REGIONAL OFFICE FOR THE WESTERN PACIFIC



WESTERN PACIFIC REGIONAL GUIDELINES:
INTRODUCING RUBELLA VACCINE

Contents

Summary 3

Purpose 3

Background 3

Disease burden 3

Risks of rubella immunization 3

Link with Regional measles elimination 4

Adding rubella vaccine 4

Timing and number of doses 4

Action for all countries 5

Incorporating rubella with measles surveillance 5

Estimating rubella disease burden 5

Considering rubella vaccine for the NIP 6

Adding rubella vaccine 6

Issues for adding rubella vaccine 6

Options for adding rubella vaccine 8

Outbreak response 9

Assessing disease burden during a rubella outbreak 9

Delivering an immunization campaign to stop the rubella outbreak 11

References 12

Acknowledgement 13

Annex 1: Rubella infection 14

Annex 2: Rubella vaccine 15

Annex 3: CRS Surveillance 16

Annex 4: Case Definitions 18

Rubella 18

Rubella encephalitis 18

Congenital Rubella Syndrome (CRS) 18

Annex 5: New vaccine introduction (NVI) capacity indicators (DRAFT) 19

Applying the NVI indicators for rubella vaccine 20

Summary

As the Region moves towards measles elimination there is an opportunity for countries to add rubella and eliminate both diseases at the same time. However, there is an important risk to rubella immunization if high coverage is not achieved and maintained. There is also the added cost of the vaccine that must be sustained.

For countries that are able to assure sustained high immunization coverage as well as the additional funding for rubella vaccine, the different options for the introduction of rubella vaccine are outlined. For all countries, it will be important to include rubella in the measles surveillance so that the importance of rubella can be assessed.

Purpose

This document provides guidelines for National Immunization Programmes (NIPs) to consider adding rubella vaccine to their immunization schedule. Such a consideration can be precipitated by an outbreak, but ideally should happen before it. The document includes guidelines for epidemiological assessment of the outbreak to provide additional information on the need for rubella immunization.

It supplements the WHO position paper on rubella vaccines,¹ the WHO discussion document,² and is set in the context of the 2003 Regional Committee Resolution on measles elimination [WPR/RC54.R3]. Measles elimination creates an opportunity to also eliminate rubella.

Background

Disease burden

Rubella occurs worldwide and is normally a mild childhood disease. However, infection during early pregnancy may cause fetal death or congenital rubella syndrome (CRS) – with multiple defects, particularly to the brain, heart, eyes and ears. Up to 90% of babies are affected if infection is early in pregnancy. Infection in the second trimester may result in deafness alone.

Rubella infection sometimes leads to serious complications, including bleeding disorders, Guillain-Barré Syndrome (GBS), and encephalitis. Encephalitis had been previously reported to occur in 1 per 6000 cases – based on limited data from the USA and Japan. In the outbreaks in Tonga (2002) and Samoa (2003), encephalitis was seen more commonly and estimated to occur in between 1 in 300 and 1 in 1,500 cases. Although most cases of rubella encephalitis have a complete recovery, there can be serious complications and even deaths. Even with complete recovery such cases cause additional burdens to families and health services that are preventable.

The higher risk of encephalitis in these two Polynesian populations may reflect host/viral factors or may represent better recognition in an area where measles is well controlled and cases are not misclassified as measles. Whatever the cause, the encephalitis risk adds to the case for rubella immunization, especially for the Pacific. (See Annex 1 for more details about rubella infection).

Risks of rubella immunization

The primary aim of rubella immunization is prevention of CRS. Immunization programmes must achieve a higher level of population immunity than natural infection or there is a risk that more pregnant women will be infected (leading to more CRS cases) than happened in the pre-vaccine era.³ This means that rubella immunization is only recommended for countries that can achieve and maintain high immunization coverage (>80%).

An additional factor is private sector use of rubella vaccine potentially increasing CRS.⁴ Private sector can reduce transmission among children leading an increase in adult susceptibility after about 20 years of use. A 2003 review of measles surveillance in selected areas of four province of China found rubella to be the leading identified cause of rash and fever. Of concern was the apparent increase in the average age of rubella infection as a result of private sale of rubella vaccine and hence a likely an increase in CRS cases in the future.

Link with Regional measles elimination

In September 2003, the Regional Committee resolved to eliminate measles from the Region. As countries move towards measles elimination, there is the opportunity to eliminate rubella at the same time. Failure to take advantage of this opportunity means ongoing rubella and fetal damage.⁵ Rubella vaccine addition can also be used as an opportunity to strengthen measles elimination efforts.

The importance of rubella in some countries may only be recognised after measles is controlled, as both cause acute fever and rash (AFR) illness. The importance of rubella infections in China is becoming evident in those areas where AFR cases are being tested for measles and rubella, with up to half of those negative for measles having rubella infection.