Research and analysis

HPR volume 10 issue 35: news (14 October)

Updated 16 December 2016

1. Seasonal flu vaccination campaign launched

Public Health England and NHS England have launched a new Stay Well This Winter (SWTW) campaign aimed at helping children and the vulnerable stay well through the 2016/17 winter and signalling the start of the biggest flu vaccination programme for children in England to date [1]. Also targetted are NHS staff and social care workers.

The SWTW campaign – aimed at achieving increased flu vaccination coverage through TV, radio and online advertising – coincides with the extension of the children’s programme to include school year 3 (children aged 7-8 years) for the first time [2], a target childhood population exceeding four million, around 600,000 more than last season. Vaccination for children aged 2, 3 and 4 years is available from their GP. Parents of school-age children are being asked permission for their children to receive the free nasal spray vaccination at school. (A recent survey showed that nearly four out of 10 parents of eligible children were unaware of the nasal spray.) Other vulnerable groups for whom free vaccine is available are those aged 65 and over, residents of long-stay care homes and carers.

The 2015/16 season was the third year of phased introduction of paediatric live attenuated influenza vaccine (LAIV) across the UK. A recently published end-of-season assessment of the effectiveness of the that season’s vaccination programme – based on data from four influenza sentinel surveillance schemes operating in England, Scotland and Wales [3] – concluded that overall, vaccine effectiveness had offered “moderate to good levels of protection, particularly against influenza B in children” [3].

1.1 References

1. “More than 4 million children to be offered flu vaccination”, PHE website news story, 12 October.
2. PHE (September 2016). Extension of the influenza programme to children in England.
3. Pebody R, Warburton F, Ellis J, Andrews N, Potts A, et al (2016). Effectiveness of seasonal influenza vaccine for adults and children in preventing influenza in primary care in the United Kingdom: 2015/16 end-of-season results. Euro Surveill, 21(38), 22 September.

2. Some evidence that TB pre-entry screening may be working

A recent study carried out by University College London and Public Health England, covering the period 2006 to 2012, has provided evidence that pre-entry TB screening has a role to play in detecting prevalent TB cases, in identifying those at risk of reactivation from latent TB, and thus to inform public health interventions in the UK [1].

Since 2014, the UK has operated a pre-entry screening programme – similar to those operated by Australia, Canada, New Zealand and USA – covering all UK visa applicants in 101 high-incidence countries worldwide (TB incidence ≥40 per 100,000 population), where the applicant intends to stay in the UK for longer than six months. Screening is based on chest X-rays and symptom enquiry, followed by sputum smear and culture tests when TB is suspected. Visa applicants found to have active, pulmonary TB, are required to successfully complete treatment before they can proceed with their application.

PHE has a key role in quality assuring the overseas programme and the PHE TB Screening Unit provides advice, training, clinic audits, data analysis and information to support the quality assurance and evaluation of the programme.

PHE’s recently published TB annual report noted that, as more pulmonary TB cases are detected by pre-entry screening overseas (382 cases were detected through pre-entry screening in 2015), the number of prevalent pulmonary TB cases notified in the UK (within one year of entry to the UK) from countries covered by pre-entry screening decreased from 380 in 2006 to 88 in 2015 [2].

The new study report, published in the Lancet [1], presents a detailed analysis of the seven-year pilot phase of the programme, when pre-entry screening was a requirement in 15 countries [3]. Among the more than half a million arrivals in England, Wales, and Northern Ireland, from countries then covered, a total of 1,873 cases of all forms of tuberculosis were identified, most of these likely reactivations of previous latent TB. Using molecular data that were available between 2010 and 2013, the study authors were able to estimate the extent to which such cases represented a risk of onward transmission in the UK. Out of 318,983 migrants who arrived over this period, 301 active TB cases were identified as likely due to reactivation of latent infection acquired abroad; of these cases, molecular data suggested that only 35 TB were likely to have caused onward transmission of TB within the UK.

The authors of the study report conclude that the pre-entry screening programme, combined with ongoing monitoring and treatment, will continue to play an important role in continuing the downward trend of TB incidence in the UK. The risk of active TB being identified, the study found, was greatest four years after arrival in the UK, suggesting that ongoing monitoring and good access to healthcare will be important in further reducing incidence.

2.1 References

1. Aldridge RW, Zenner D, White PJ , Williamson EJ, Muzyamba MC, et al (2016). Tuberculosis in migrants moving from high-incidence to low-incidence countries: a population-based cohort study of 519,955 migrants screened before entry to England, Wales, and Northern Ireland. Lancet online, 11 October.
2. PHE (2016). Tuberculosis in England: 2016.
3. PHE (2013). UK pre-entry tuberculosis screening brief report 2013.

3. Evidence of media-generated healthcare-seeking behaviour following a boiled water notice

Following detection of Cryptosporidium oocysts in a public water supply in the north west of England in August 2015, Public Health England’s Real-time Syndromic Surveillance Team (ReSST) detected statistically significant increases in the presentation of cases of gastroenteritis and diarrhoea to general practitioner and other healthcare services in the affected areas.

Considering the incubation period of cryptosporidiosis and the possible exposure of the population to the organism, the timing of the observed increases in syndromic indicators (potentially related to gastroenteritis and diarrhoea) suggested it was plausible that an increase in infections had occurred. Furthermore, increases in diarrhoea and gastroenteritis (GI) indicators – but not of vomiting – were also in line with symptom presentation typical of cryptosporidiosis.

Yet, according to the results of a study by ReSST and other PHE scientists who subsequently reviewed the available microbiological and epidemiological data [1], the significant increases seen in syndromic surveillance indicators – GP in-hours and out-of-hours calls, and calls to the National Health Service telephone advice line (NHS 111) – were potentially an indirect result of the “boil water notice” (BWN) issued by the local authority at the time.

The authors conclude that it was the amplification of the BWN message by print and digital media (“intense local and national media coverage of the potential health risks during the event”) that was potentially responsible for the elevated “healthcare-seeking behaviour” recorded in the syndromic surveillance indicators monitored by ReSST, and not any real increase in cryptosporidium-related GI infections.

There was a small exceedance in cryptosporidium laboratory detections at the time of the incident, the authors note, but this could be explained by a coincident national, seasonal increase across England. The authors conclude, “There was … insufficient information to link individual cases within BWN areas to the local water supply, or there were other risk factors (eg history of travel) involved …. It was highly likely that the increase in healthcare seeking behaviour monitored by syndromic surveillance during the BWN was due to intense local and national media reporting, rather than actual cryptosporidium infections”.

This study indicates, the authors’ note, the potential for media-driven bias in syndromic surveillance and highlights the difficulties involved in identifying true increases in rates of community infection.

3.1 Reference

1. AJ Elliot AJ, Hughes HE, Astbury J, G Nixon G, K Brierley K, Vivancos R, et al (2016). The potential impact of media reporting in syndromic surveillance: an example using a possible Cryptosporidium exposure in North West England, August to September 2015. Euro Surv, 21(41), 13 October.