Research and analysis

HPR volume 10 issue 29: news (2 September)

Updated 16 December 2016

1. Singapore Zika virus outbreak

The Ministry of Health, Singapore, has confirmed 38 new cases of locally-transmitted Zika virus infection (as at 2 September), confirming that active transmission is occurring in the country [1].

Both Singapore and the British Virgin Islands have been recently added to the countries listed on the PHE website as high risk for the infection and to which therefore pregnant women should avoid travel [2].

The National Travel Health Network & Centre’s website provides more detailed summaries of outbreaks occurring in different parts of the world [3].

1.1 References

1. Singapore Ministry of Health website (2 September 2016).
2. PHE website. Zika virus: country specific risk.
3. NaTHNaC Travel Health Pro (30 August, 2016). Outbreak surveillance: Zika.

2. WHO Emergency Committee extends wild poliovirus recommendations

The tenth meeting of the WHO IHR Emergency Committee concerned with the international spread of wild poliovirus, convened on 11 August, reviewed the data on circulating vaccine-derived polioviruses (cVDPV) as well as circulating wild poliovirus (WPV 1). The Committee was concerned by the two new cases of WPV 1 reported from different local government areas (Gwoza and Jere) in Borno State, Nigeria, during July 2016. These cases, together with the cVDPV reported in May 2016, suggested polioviruses have been circulating undetected in Borno for several years and indicate significant gaps in surveillance.

The Committee was concerned that Gwoza district borders with the north province of Cameroon and is considered inaccessible. Historically poliovirus transmission has occurred in the Lake Chad area, and the international borders around Borno with Cameroon, Chad and Niger, such that the risk of international spread between these four countries was considered extremely high and might already be occurring.

The progress being made in Afghanistan and Pakistan was recognised and it was noted that there had been no spread of WPV 1 between these two countries since the previous meeting. The Committee was, however, concerned at the deteriorating security in parts of Afghanistan making more children inaccessible, and potentially delaying the completion of global polio eradication in 2016. Globally there were significant vulnerable areas and populations that were inadequately immunised due to conflict and poor coverage. These vulnerable areas included countries in the Middle East, the Horn of Africa, and Central Africa.

The Committee agreed that the situation still constituted a Public Health Emergency of International Concern (PHEIC) and recommended the extension of the temporary recommendations for a further three months to the following countries:

Countries currently exporting wild poliovirus (WPV) or cVDPV:

• Afghanistan (last exportation WPV, 6 June 2015);
• Pakistan (last exportation WPV, 1 February 2016).

Countries infected with wild poliovirus or cVDPV detected in the last six months but not currently exporting:

• Nigeria (WPV 1 and cVDPV);
• Guinea (cVDPV);
• Laos People’s Democratic Republic (cVDPV);
• Madagascar (cVDPV);
• Myanmar (cVDPV).

In addition, all travellers to Somalia, Equatorial Guinea, Cameroon, Niger, Chad and Ukraine should ensure they have had a full primary course of poliomyelitis vaccine and be offered a booster if it has been more than 10 years since their last dose. While these countries were no longer infected with wild poliovirus or cVDPV, they remained vulnerable to international spread or to the emergence and circulation of VDPV.

2.1 Reference

1. WHO (22 August 2016). Statement on the tenth IHR Emergency Committee meeting regarding the international spread of poliovirus.

3. Results of mathematical modelling of pertussis transmission dynamics published

Mathematical models developed to describe pertussis transmission dynamics in England and Wales, to explore the likely causes of the resurgence in cases seen in 2012 and to inform future decisions on immunisation strategy are described in a new paper from PHE scientists [1].

The pertussis resurgence that occurred in England and Wales in 2012 resulted in an increase in deaths and hospitalisations among infants too young to have received their first dose of vaccine under a primary immunisation schedule (delivered at 2, 3, and 4 months of age). To provide immediate, passive protection to vulnerable infants, a vaccination programme for pregnant women was introduced, as a temporary outbreak control measure, which has successfully reduced pertussis morbidity and mortality among infants in England. Its long-term continuation will depend on the extent to which elevated levels of pertussis continue.

Notwithstanding methodological limitations, the statistical models described in the paper offer insights into both the likely cause of the resurgence in cases and the relative merits of different control strategies. The most likely explanation is the choice of vaccine used in the primary immunisation schedule, which changed from a whole cell to an acellular preparation in 2004. With the elevated incidence of infant disease predicted to continue, there will be a continuing need for a programme to protect vulnerable pre-vaccination infants, the paper concludes. Other alternative immunisation strategies are discussed, including whether an adolescent booster might be justified.

3.1 Reference

1. Choi YH, Campbell H, Amirthalingam, van Hoek AJ, Miller E (2016). Investigating the pertussis resurgence in England and Wales, and options for future control. BMC Medicine, 1 September.

4. Developing programme of childhood influenza immunisation reviewed

PHE has published a comprehensive review of practical experience gained to date from the use of live attenuated influenza vaccine in school-age children after three years’ operation of pilot programmes and the start of phased roll-out of a national programme in England during the 2015/16 season [1].

This follows the release in June of provisional data on the effectiveness of the childhood influenza vaccine programme in 2015/16, which was nearly 58% against laboratory confirmed infection in primary care amongst children and adolescents [2].

The review presents an overview of the arrangements for the LAIV pilot and national programmes, including: prescribing arrangements; workforce and administrative requirements; engagment with schools; management of immunisation sessions; communications with health professionals, parents and the media; and the pros and cons of parental attendance, self-adminstration of the vaccine, and post-vaccination monitoring.

In 2015/16 the national programme was extended to children of age appropriate for school years 1 and 2 (ie children who were aged 5-6 years and 6-7 years, respectively).

No new major issues came to light during the national roll out to all children in these age cohorts in 2015/16 but many of the lessons learned during piloting the previous two seasons were reinforced.

In 2016/17 children of age appropriate for school year 3 (children who will then be aged 7-8 years) will be eligible for vaccination. The intent is that the programme will gradually extend over future years to all primary school aged children in England. Once extended to all primary school age children, the roll-out will pause to assess the epidemiological data and enable the JCVI to further consider whether extension to secondary school age children is necessary.

4.1 References

1. PHE (September 2016). Extension of the influenza programme to children in England.
2. PHE (June 2016). Influenza vaccine effectiveness in adults and children in primary care in the UK: provisional end-of-season results 2015 to 2016.