Winter health watch summary: 23 March 2017
Published 30 March 2017
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1. Summary
1.1 Cold Weather Alert
All regions are at level 1 – Winter preparedness and alert. Temperatures and weather conditions are not expected to exceed cold weather alert threshold criteria in any region until further notice.
Prior 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
- 28 November to 6 December 2016
- 27 December to 31 January 2017
- 5 to 13 February 2017
- 23 February to 25 February 2017
- 27 February to 4th March 2017
1.2 Flu
During week 11 (ending 19 March 2017), influenza activity continues to decrease across all indicators. The Department of Health has issued an alert on the prescription of antiviral medicines by GPs.
1.3 Syndromic Surveillance
There were increases in asthma, wheeze or difficulty breathing conditions during week 11 (within seasonally expected limits), that were particularly noted in children.
1.4 Norovirus
Reports of suspected and confirmed outbreaks of norovirus in hospitals continue to be reported at lower levels than in previous years.
The number of laboratory reports of norovirus in this season* (since week 27 in 2016) is 4516. This is 9% lower than the average number for the same period in the 5 seasons from season 2011 and 2012 to season 2015 and 2016 (4948), and 28% 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 season. Therefore, it is more appropriate to use the 5 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 in 2016) is 2574. This is 59% lower than the 10 season average for the same period in the seasons 2003 and 2004 to 2012 and 2013 (6234)** and 53% higher than the 3 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
During week 11 in 2017, no statistically significant excess all-cause mortality by week of death was seen through the EuroMOMO algorithm in England overall or by age group.
*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 in 2009 to week 26 in 2010, July to June. Data for 2009 and 2015 exclude week 53.
**Comparison is made with this 10 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
Met Office Get Ready for Winter
4. Planning resources
Cold weather plan for England