Research and analysis

HPR volume 9 issue 18: news (21 May)

Updated 29 December 2015

1. UK seasonal influenza annual report 2014 to 2015 in summary

Moderate levels of influenza activity were seen in the community in the United Kingdom (UK) in 2014 to 2015, with influenza A(H3N2) the predominant virus circulating for the majority of the season, and influenza B circulating later in the season. The impact of H3N2 was predominantly seen in the elderly, with numerous outbreaks in care homes and levels of excess mortality higher than the last notable H3N2 season of 2008 to 2009. Peak admissions to hospital and intensive care were higher than seen in recent seasons, but lower than the last notable season of 2010 to 2011.

These are among the conclusions of the PHE report on influenza and other respiratory viruses in the UK during the winter of 2014 to 2015 [1]. The annual report is produced by PHE’s Respiratory Diseases Department in collaboration with the health protection bodies of the Devolved Administrations, and other national data providers across the UK. It includes summary information for the UK on flu-related mortality and morbidity, and on vaccine uptake data. It also includes updates on the extent of circulation of novel respiratory viruses (including avian-origin influenza) outside of the UK – in the Middle East, Egypt and Eastern China – that are being monitored despite the current low risk to UK residents.

1.1 Influenza vaccine uptake and effectiveness

Influenza vaccine uptake in 2014 to 2015 in England was similar to recent seasons in the elderly (72.7%) and in healthcare workers (54.6%), and slightly lower in under 65 year olds in a pre-defined clinical risk group (50.3%). An increase was seen in pregnant women (44.1%) compared to 2013 to 2014 (39.8%).

In 2014 to 2015, the universal childhood influenza vaccine programme with live attenuated influenza vaccine (LAIV) was offered to all 2, 3 and 4 year olds in England, achieving an uptake of 38.5%, 41.3% and 32.9% respectively. A pilot LAIV programme for children of primary and secondary school age (4 to 13 years) in England, achieved an overall uptake of 53.2%.

The UK mid-season overall adjusted vaccine effectiveness (VE) in preventing influenza A confirmed infection in primary care was low, likely reflecting the mismatch between circulating A(H3N2) viruses and the 2014 to 2015 Northern Hemisphere vaccine strain. Work continues to evaluate the impact of the LAIV programme in terms of both direct and indirect protection for the general population across the country. The importance of ensuring high uptake in target groups for the national influenza vaccination programme for the forthcoming influenza season remains.

1.2 Other respiratory viruses

Activity from other circulating seasonal respiratory viruses was similar to levels reported in recent years. Two novel respiratory viruses which emerged in 2012 to 2013, Middle East Respiratory Syndrome coronavirus (MERS-CoV) in the Middle East and avian-origin influenza A(H7N9) in Eastern China, have continued to result in human cases in affected countries in 2014 to 2015. There has also been an unprecedented number of human infections with avian influenza A(H5N1) reported in Egypt in 2015. Surveillance and public health measures established in the UK for travellers returning with severe respiratory disease from these regions are on-going while the risk remains.

1.3 Reference

1. PHE. Surveillance of influenza and other respiratory viruses in the United Kingdom: winter 2014 to 2015.

2. Investigation of M. chimaera infection associated with cardiopulmonary bypass: an update

As reported on 30 April [1], cases of invasive Mycobacterium chimaera infection have been reported in patients who have undergone cardiac surgery in Switzerland and the Netherlands. A Swiss investigation has been published attributing these infections to aerosol generated by contaminated heater cooler units (HCUs) used during cardiopulmonary bypass [2]. A case of similar infection has also been reported in Germany and a rapid risk assessment has been published by the European Centre for Disease Prevention and Control [3]. Of the cases to date in Europe, 3 fatal outcomes have been reported.

PHE has conducted an investigation in the UK, in partnership with the NHS, MHRA, Public Health Wales, Health Protection Scotland and the Public Health Agency of Northern Ireland. This included microbiological assessment of HCUs and retrospective case finding.

Microbiological investigation at multiple hospital sites in the UK has indicated that non-tuberculous mycobacteria (common environmental organisms) can be found in the water within HCUs. Non-tuberculous mycobacteria have also been detected in the air around the devices at some of these sites. The investigation to date has focused on the model of HCU which is most commonly used in the UK, which is the same as those described in the Swiss report. It is not clear whether any risk is limited to a particular model or brand of HCU.

Retrospective case finding was conducted to look for patients with similar infections to those reported in Switzerland (M. chimaera or other M. avium complex endocarditis, surgical site infection or disseminated infection within 4 years of surgery involving cardiopulmonary bypass). A small number of patients (13) who fulfill these criteria have been found in the UK and are the subject of ongoing investigations. These patients had surgery in many different hospitals in the UK between 2007 and 2014. A definitive link between the heater cooler units and the patient infections has not been established by the UK investigation. Further microbiological investigations are underway.

PHE and the MHRA continue to investigate this risk and are working with manufacturers, the NHS and ECDC to identify solutions for cardiothoracic centres.

2.1 References

1. Investigation of Mycobacterium chimaera infection associated with cardiopulmonary bypass, HPR 9(15), 30 April 2015.
2. Sax H, Bloemberg G, Hasse B, Sommerstein R, Kohler P, Achermann Y et al (2015). Prolonged outbreak of Mycobacterium chimaera infection after open-chest heart surgery. Clin Infect Dis (online, March 11).
3. European Centre for Disease Prevention and Control. Invasive cardiovascular infection by Mycobacterium chimaera potentially associated with heater-cooler units used during cardiac surgery, 30 April 2015.