Research and analysis

HPR volume 9 issue 1: news (9 January)

Updated 29 December 2015

1. Ebola virus disease: international epidemiological summary (at 4 January 2015)

Up to the end of 4 January (2 January for Liberia), a total of 20,747 clinically compatible cases (CCC) of Ebola virus disease (EVD), including 8,235 deaths, have been recorded associated with the outbreak in west Africa. The case totals – and particularly the recorded deaths – are known to under-represent the true impact of the outbreak.

While the majority of cases have been reported from Guinea, Liberia and Sierra Leone, cases have also been reported from Senegal, Nigeria, Mali, Spain, the United States of America (USA) and the United Kingdom (UK).

The trends in national incidence continue to vary across Guinea, Liberia and Sierra Leone. In Guinea, the incidence nationally has fluctuated since September without clear evidence of either upward or downward trend. From the latest information available from Liberia (five days of data compared to seven days for Guinea and Sierra Leone), case incidence continues to decline and transmission remains at a low level restricted mainly to Montserrado county, which includes the capital Monrovia.

In Sierra Leone, while the latest figures contribute to the evidence that the increase in national incidence has slowed, there continues to be significant transmission particularly in the western districts, with over three times as many new confirmed cases reported there in the last week as in Guinea and Liberia combined.

Case fatality rates remain high across Guinea, Liberia and Sierra Leone where for cases with a definitive outcome the rate is 71%. For hospitalised patients, the case fatality rate is lower at 60% in Sierra Leone and 58% in Guinea and Liberia.

Since December 2013, six countries have reported a case, or cases, imported from a country with intense and widespread transmission: Mali and the UK (defined as currently affected countries) and Nigeria, Senegal, Spain and USA (defined as previously affected countries).

The total number of EVD CCC reported in Mali remains at eight. The last patient tested negative on 6 December, and was discharged from hospital on 11 December. All contacts of infected patients have passed the 21 day observation period. If no new cases arise, Mali will be declared EVD-free on 18 January 2015. The situation in Mali looks encouraging but given the porous nature of the Mali-Guinea border, the risk of further importation of cases is recognised.

On 29 December, the Scottish government reported a confirmed case of EVD in a healthcare worker (HCW) who had recently returned from working in an Ebola treatment unit in Sierra Leone. Following the confirmation of EVD, the patient was transferred from Glasgow to London and is currently receiving treatment in the Royal Free Hospital. Tracing of contacts of the case has now been completed (PHE). The risk to the UK public from EVD continues to be very low [1].

To date, a total of 24 EVD cases have been cared for outside of Africa. Of these, 18 repatriated cases (hospitalised in USA, Spain, UK, Germany, France, Norway, Switzerland, Italy and the Netherlands), three imported cases (diagnosed in the USA and the UK) and three incidents of local transmission (in Spain and the USA).

The table below summarises Ebola virus disease international epidemiological information as at 4 January 2015 (2 January for Liberia)

Country	Total CCCs	Total deaths	Current status
Guinea	2775	1781	Ongoing transmission
Liberia	8157	3496	Ongoing transmission
Sierra Leone	9780	2943	Ongoing transmission
Mali	8	6	Awaiting EVD free status
UK	1	0	Single imported case
Nigeria	20	8	EVD free
Senegal	1	0	EVD free
Spain	1	0	EVD free
USA	4	1	Awaiting EVD free status
TOTAL	20,747	8235	–

Further information on the international epidemiological situation can be found in PHE’s weekly Ebola epidemiological update.

1.1 Reference

1. PHE guidance. “Ebola virus disease: risk assessment of outbreak in West Africa”, 8 December 2014.

2. UK influenza activity in the 2014/15 season: an update

The 2014/15 influenza season to date has reached overall activity levels higher than the peak seen during the previous three seasons. It has not reached the levels seen in the last notable seasons of 2008/9 and the immediate post-pandemic season of 2010/11. UK influenza activity started to rise noticeably in week 49, 2014 [1], with the Department of Health issuing an alert on the prescription of antiviral medicines by GPs according to NICE guidance on 16 December 2014 [2].

The recent data need to be interpreted cautiously due to the Christmas and New Year holidays. However, the latest data in this week’s Weekly National Influenza Report [3] do show that:

• an increasing number of acute respiratory outbreaks are being reported across the UK, with most occurring in care homes
• the overall GP consultation rate has continued its gradual upward trend in adults (predominantly in the elderly) although the rate in children has started to drop
• influenza positivity has also started to drop in all age groups (with the highest positivity in those aged 65 and over, at 44.6%) except in the 45-64 years group where it remained at an elevated level (31.3%) similar to last week
• influenza hospitalisation rates have continued to rise but ICU/HDU influenza admission rates started to show signs of decreasing.

The dominant circulating influenza virus this season to date has been A(H3N2), with very low levels of influenza A(H1N1)pdm09 and influenza B viruses also circulating.

The emergence of influenza A(H3N2) drift variants has been described in 2014 from the US [4] and elsewhere. In the UK this winter, five out of 24 (20.8%) antigenically characterised A(H3N2) viruses to date have showed reduced reactivity in antigenic tests with antiserum raised to the H3N2 vaccine strain (A/Texas/50/2012). It is not known at this stage whether the drift variant will become the dominant strain, nor to what extent such a drift will result in reduced effectiveness of the 2014/15 vaccine.

So far this season, 26/27 influenza isolates have been tested and shown to be oseltamivir and zanamivir sensitive (eight A(H1N1)pdm09, 10 A(H3N2) and eight B), the remaining one however (a child with influenza A(H3N2) infection) has been found to have an amino acid substitution in the neuraminidase gene known to cause resistance to oseltamivir and reduced susceptibility to zanamivir, and this child had received oseltamivir treatment.

Flu vaccine uptake data this season up to week 1, 2015, has reached 71.7% in those aged 65 and over; 48.9% in the <65 at risk group; 48.2% in the frontline health workers; 43.1% in pregnant women; 37.2% in all two-year-olds; 39.8% in all three-year-olds; and 31.5% in all four-year-olds.

Existing vaccine provides the best available protection from flu and getting vaccinated remains the best way to protect those at risk from flu. Eligible patients should continue to be encouraged to get the vaccine for free as they are at much greater risk of becoming seriously unwell if they catch flu.

PHE will continue to monitor the epidemiological and virological situation closely. Influenza vaccine and antivirals for appropriate target groups remain key interventions to reduce the health impact of influenza.

2.1 References

1. PHE. Weekly National Influenza Report (week 50 report, data to week 49/2014), 11 December 2014.
2. DH. Influenza season 2014/15 – use of antiviral medicines, CMO/CPO letter, 16 December 2014.
3. PHE. Weekly National Influenza Report (week 2 report, data to week 1/2015), 8 January 2015.
4. CDC. Health Advisory regarding the potential for circulation of drifted Influenza A(H3N2) viruses, 3 December 2014.