Expanded programme on immunization

Sixth Meeting of Vaccine-Preventable Diseases Laboratory Networks in the Western Pacific Region

12 -15 September 2016, Manila, Philippines

The Sixth Meeting of Vaccine-Preventable Diseases Laboratory Networks in the Western Pacific Region was held in Manila, Philippines from 12 to 15 September 2016 to review the performance and identify the challenges of the polio and measles and rubella network laboratories in the Region. The meeting reviewed ways to further strengthen the performance of network laboratories and also to monitor the implementation of recommendations from the fifth vaccine-preventable diseases laboratory networks meeting in May 2015.

The meeting also provided an opportunity to discuss ways to improve the quality and timeliness of laboratory testing in countries experiencing large measles outbreaks and the importance of improving molecular surveillance for measles and rubella. The implications of the switch to bivalent oral polio vaccine (OPV) and the containment of poliovirus type 2 (PV2) on the laboratory networks were deliberated.

Polio Laboratory Network

A two-day session for the polio laboratory network in the Western Pacific Region was organized from 12 to 13 September 2016 to discuss global progress towards polio eradication, to identify challenges in maintaining polio-free status in the Western Pacific Region, to share updates on global and regional polio laboratory networks, to review the performances of the polio network laboratories and to discuss the implementation of new polio containment requirements following the global switch to bivalent OPV. The meeting concluded that the performance of the regional polio laboratory network has been sustained at polio-free-certification standard and that acute flaccid paralysis (AFP) surveillance activities have been efficiently supported. The network laboratories provided critical evidence in support of the continued polio-free status of the Region. As of August 2016, all 43 network laboratories are accredited including all 38 polio laboratories with ITD function.

Since the Western Pacific Region has been polio-free for more than 10 years, network laboratories have been actively involved in supplementary enterovirus or environmental surveillance. China established an extensive HFMD laboratory network based on existing polio laboratories, and Japan and Viet Nam have also implemented HFMD surveillance. The polio laboratories in Australia, China, Japan and Malaysia are involved in testing samples collected from environmental surveillance, and the Philippines’ laboratory has undergone training and will start environmental surveillance in late 2016. In the Region in 2015, China detected three VDPVs in AFP cases, two of which were determined to be “ambiguous” and one from an immunodeficient case. None showed spread after extensive investigation. A number of circulating VDPV type 1 viruses were detected in the Lao People's Democratic Republic in late 2015 and early 2016. Viruses were found in AFP cases (N=11) and contacts (N=25). Extensive surveillance following eight rounds of supplemental immunization has not detected cases since January 2016. The continued use of environmental and enterovirus surveillance in a number of countries and areas in the Region has provided valuable data to support evidence of the continued polio-free status of the Region.

The global switch to bivalent OPV in April 2016 has had wide-reaching implications for all laboratory networks, particularly the global polio laboratory network (GPLN). Poliovirus type 2 was declared eradicated. Post eradication, all type 2 polioviruses or material potentially infected with PV2 must be destroyed or handled in poliovirus essential facilities (PEFs) with biosafety level 3 plus capacity. It was proposed that the Western Pacific Region would have three PEFs: the polio network laboratories in Australia, China and Japan. The algorithm for all other polio network laboratories to safely send any PV2 virus detected in the future to the PEFs was communicated. Considerable efforts have been made to achieve polio eradication in the Region with a critical contribution from the polio laboratory network. Continuous strong quality assurance procedures and training activities to enhance the sensitivity of detecting wild and vaccine-derived poliovirus are being implemented in the Region, ensuring high-performance, high-quality laboratory support.

Measles and Rubella Laboratory Network

A two-day session of the regional measles and rubella laboratory network was organized from 14 to 15 September 2016 to review progress, identify challenges and develop plans to further strengthen the performance of network laboratories including molecular capacity in support of measles and rubella elimination. The meeting concluded that measles and rubella network laboratories have helped in working towards the regional goal of measles and rubella elimination by confirming suspected cases and identifying measles and rubella virus genotypes circulating in the Region. The laboratory network has played a critical role in the recent verification of measles elimination of seven Member States by identifying that measles cases found in these countries are imported rather than due to endemic circulation. The network consists of one global specialized laboratory (GSL) in Japan, three regional reference laboratories (RRLs) in Australia, China and Hong Kong SAR (China), 13 fully functional national measles and rubella laboratories, 31 provincial and 331 prefectural laboratories in China, and three subnational laboratories in Malaysia and Viet Nam.

As the role of the measles and rubella laboratory network extends to molecular surveillance for confirming and maintaining verification of measles elimination, laboratories with virus isolation, molecular testing and sequencing capabilities were encouraged to collect samples for sequencing and genotyping for measles and especially rubella. Genotype and sequence information for measles are submitted to the WHO sequence database for measles, MeaNS, for 11 of the 13 countries reporting laboratory-confirmed cases. For rubella, sequences are submitted to the RubeNS genotype database for five of the 16 countries in the Region reporting confirmed rubella cases. Countries that have experienced large measles outbreaks are considering establishing a subnational network of laboratories to spread the workload and improve timeliness of reporting. China has had a well-established subnational network since 2000, Viet Nam has two subnational laboratories, and Malaysia has one. The Philippines is investigating the logistics and economics of establishing a subnational network of laboratories that will test for measles and rubella as well as Japanese encephalitis (JE) and participate in AES surveillance. Establishing CRS surveillance in countries in the Region is a challenge; however, the appropriate laboratory testing strategy is being developed in collaboration with the Global Specialized Laboratories at the United States Centers for Disease Control and Prevention (US CDC) and the National Institute of Infectious Diseases (NIID), Japan.

The implementation of GAP III containment of polioviruses and potentially infectious material will have an impact on the measles and rubella laboratory network. Any respiratory or faecal sample collected for any purpose in a time and geographic area of OPV use is presumed potentially infectious for polioviruses (Sabin) unless otherwise demonstrated, under GAP III guidelines. As many measles and rubella laboratories have stored throat swabs collected during such a period, they may not be aware that these samples are now considered as potentially infectious for polioviruses and the need to meet the deadline for completing an inventory of such material. If considered a high risk, these samples may be required to be shipped to a PEF, non-polio essential facility or destroyed.

The regional measles and rubella laboratory network has made considerable progress since establishment began in 1998. The network now includes 386 laboratories that are all following WHO-recommended methods and procedures under a strong environment of quality assurance. A total of 120 000 serum samples from suspected measles cases were tested in 2015 and reported timely and accurately. More than 3200 measles virus sequences and 300 rubella sequences were reported to the WHO genotype databases in 2015, allowing informed decisions on the molecular surveillance of measles and rubella globally and in the region.