Research and analysis

Winter health watch summary: 5 January 2017

Published 30 March 2017

1. Summary

1.1 Cold Alert

A level 3 Cold Weather Alert is in place for all regions in England, and is in place from 9am on Wednesday 4 January and 3pm on Friday 6 January. This most recent alert is the continuation of a series of alerts that have been in place since 27 December 2016.

Prior level 2 cold weather alerts have been in place this season from 8 to 9 November 2016, 18 to 21 November 2016, 24 to 26 November 2016 and 28 November to 6 December 2016.

1.2 Flu

During week 52 (ending 1 January 2017), influenza is circulating. Allowing for Christmas reporting breaks increases were seen in influenza-associated outbreaks in the community, the proportion of laboratory samples positive for influenza in primary and secondary care and influenza-related admissions to hospital and intensive care. The Department of Health has issued an alert on the prescription of antiviral medicines by GPs.

1.3 Syndromic Surveillance

During week 52 respiratory indicators, including NHS111 cold/flu calls and GP consultations for influenza-like illness, pneumonia and severe asthma continued to rise in adults, particularly in the elderly.

1.4 Norovirus

Reports of suspected and confirmed outbreaks of norovirus in hospitals continue to be reported; retrospective reports are being uploaded for outbreaks that occurred in recent weeks and therefore monthly totals could rise.

The number of laboratory reports of norovirus in this season* (since week 27 2016) is 2602. This is 8% higher than the average number for the same period in the five seasons from season 2011 and 2012 to season 2015 and 2016 (2403), and 66% higher than the same weeks last season. Norovirus activity varies from season to-season, and the level of norovirus activity was lower than average during the 2015 and 2016. Therefore it is more appropriate to use the five season average for comparison. Due to this variability between norovirus seasons, it is not possible to predict how the current season will progress.

The most commonly detected norovirus strains in circulation this season belong to the Sydney2012 cluster of GII.4 noroviruses. This group of GII.4 norovirus strains have been circulating worldwide since 2012.

1.5 Rotavirus

The number of laboratory reports of rotavirus in this season* (since week 27 2016) is 1198. This is 1% higher than the ten season average for the same period in the seasons 2003 and 2004 to 2012 and 2013 (1188)** and 18% higher than the three season average for the same period in the post-vaccine seasons 2013 and 2014 to 2015 and 2016.

In the first season following the introduction of the rotavirus vaccine in July 2013, a 77% decline in laboratory-confirmed rotavirus infections in infants was observed (Atchison et al, 2016). The total number of laboratory-confirmed rotavirus infections each season has since remained low compared to the pre-vaccine period.

There may be some fluctuation in activity due to low numbers of infections in the early part of the season when compared to the same period prior to use of the vaccine. Furthermore, most laboratory tests in use do not distinguish vaccine from wild-type rotavirus. In the post-vaccine period, further characterisation of laboratory-confirmed rotavirus infections should be considered. Broader testing of cases among eligible infants for other enteric pathogens should also be considered to avoid over-attributing rotavirus as a cause of infectious intestinal disease in young children.

1.6 All-Cause Mortality

In week 50 2016, no statistically significant excess all-cause mortality by week of death was seen through the EuroMOMO algorithm in England overall and by age group.

Please note mortality statistics will resume on 19 January.

*In order to capture the winter peak of activity in one season, for reporting purposes, the norovirus and rotavirus season runs from week 27 in year 1 to week 26 in year 2, for example week 27 2009 to week 26 2010, July to June.

**Comparison is made with this ten season period as it is prior to the vaccine introduction.

2. Surveillance reports updated weekly

PHE syndromic surveillance page

PHE national seasonal influenza report

PHE norovirus and rotavirus: summary of surveillance

PHE weekly all-cause mortality surveillance

3. Further information

NHS Choices winter website

Met Office Get Ready for Winter

Keep warm keep well: information for over 60s, low income families and people living with a disability

4. Planning resources

Cold weather plan for England

Annual flu programme