H5N1

Flu News Europe, week 10

Flu News Europe has published its week 10 (March 4-10) update. Excerpt:

• Influenza activity was widespread in the European Region. Specimens collected from individuals presenting with ILI or ARI to sentinel primary health care sites yielded an influenza virus positivity rate of 42.8%. 

• Influenza type A virus detections dominated with slightly more A(H1N1)pdm09 than A(H3N2) viruses. Very few influenza B viruses were detected. 

• 28.3% of specimens from patients with severe acute respiratory infection (SARI) collected in week 10/2019 tested positive for influenza virus, and almost all were type A. 

• Pooled data from 22 Member States and areas reporting to the EuroMOMO project indicated that the excess mortality observed in previous weeks continued to decline. Excess mortality was seen in persons aged 65 years and above and, to a lesser extent, in persons 15-64 years.

Co-circulation of influenza A(H1N1)pdm09 and influenza A(H3N2) viruses, WHO European Region, October 2018 to February 2019

Eurosurveillance has published Co-circulation of influenza A(H1N1)pdm09 and influenza A(H3N2) viruses, World Health Organization (WHO) European Region, October 2018 to February 2019. The abstract:

In the World Health Organization European Region, the 2018/19 influenza season started in week 49 2018, crossing 10% virus-positivity in sentinel surveillance specimens. At week 5 2019, activity remained elevated with positivity rates at 55%. Both A(H1N1)pdm09 and A(H3N2) viruses circulated widely and detection levels in primary care and hospital settings were similar to past seasons. Hospitalisation data may suggest an increased susceptibility to A(H1N1)pdm09 virus in older age groups.

Interim 2018/19 influenza vaccine effectiveness: Six European studies, October 2018 to January 2019

Eurosurveillance has published Interim 2018/19 influenza vaccine effectiveness: six European studies, October 2018 to January 2019. The abstract:

Influenza A(H1N1)pdm09 and A(H3N2) viruses both circulated in Europe in October 2018–January 2019. Interim results from six studies indicate that 2018/19 influenza vaccine effectiveness (VE) estimates among all ages in primary care was 32–43% against influenza A; higher against A(H1N1)pdm09 and lower against A(H3N2). Among hospitalised older adults, VE estimates were 34–38% against influenza A and slightly lower against A(H1N1)pdm09. Influenza vaccination is of continued benefit during the ongoing 2018/19 influenza season.

WHO: Recommended composition of influenza virus vaccines for use in the 2019-2020 northern hemisphere influenza season

WHO has published Recommended composition of influenza virus vaccines for use in the 2019-2020 northern hemisphere influenza season. From WHO's email:

The WHO Consultation and Information meeting on the Composition of Influenza Virus Vaccines for use in the 2019-2020 Northern Hemisphere Influenza Season has concluded today, 21 February 2018, in Beijing, with the recommendations on the composition of the influenza vaccines for the following influenza season.

The periodic replacement of viruses contained in influenza vaccines is necessary in order for the vaccines to be effective due to the constant evolving nature of influenza viruses, including those circulating and infecting humans.

Twice annually, WHO organizes consultations with an advisory group of experts to analyse influenza virus surveillance data generated by the WHO Global Influenza Surveillance and Response System (GISRS), and issues recommendations on the composition of the influenza vaccines for the following influenza season.

These recommendations are used by the national vaccine regulatory agencies and the pharmaceutical companies to develop, produce and license influenza vaccines.

It is recommended that quadrivalent vaccines for use in the 2019-2020 northern hemisphere influenza season contain the following:

• an A/Brisbane/02/2018 (H1N1)pdm09-like virus;
• an A(H3N2) virus to be announced on 21 March 2019*;
• a B/Colorado/06/2017-like virus (B/Victoria/2/87 lineage); and
• a B/Phuket/3073/2013-like virus (B/Yamagata/16/88 lineage).

It is recommended that the influenza B virus component of trivalent vaccines for use in the 2019-2020 northern hemisphere influenza season be a B/Colorado/06/2017-like virus of the B/Victoria/2/87-lineage.

* In light of recent changes in the proportions of genetically and antigenically diverse A(H3N2) viruses, the recommendation for the A(H3N2) component has been postponed.

Flu News Europe week 6 update

Via Flu News Europe:

Week 6/2019 (4 -10 February 2019) 

• Influenza activity is widespread in the European Region. Specimens collected from individuals presenting with ILI or ARI to sentinel primary health care sites yielded an influenza virus positivity rate of 53%, slightly lower than in the previous week (58%). 

• Influenza type A virus detections dominated with A(H1N1)pdm09 viruses and A(H3N2) viruses co-circulating. Very few influenza B viruses were detected. 

• 46% of specimens from patients hospitalized with severe acute repiratory infection (SARI) collected in week 6/2019 were positive for influenza virus, and all were type A. 

• Pooled data from 24 Member States and areas reporting to the EuroMOMO project indicated excess mortality mostly among elderly aged 65 years and above, but also in adults in the age group of 15-64 years. 

2018/19 season overview  

• Influenza activity in the European region, based on sentinel sampling, exceeded a positivity rate of 10% in week 49/2018 and has increased continuously into week 5/2019 after which it started to decrease. The positivity rate has exceeded 50% since week 3/2019. 

• Both influenza A virus subtypes are circulating widely, with co-circulation in some countries while others report dominance of either A(H1N1)pdm09 or A(H3N2) viruses.  

• Among hospitalized influenza virus-infected patients admitted to ICU wards, 40% of influenza A viruses were subtyped; of these 78% were A(H1N1)pdm09 virus. Among influenza virus-infected patients admitted to other wards, 28% of influenza A viruses were subtyped and 71% were A(H1N1)pdm09 virus. 

• Over 90% of influenza A viruses detected from SARI surveillance since week 40/2018 were subtyped and 81% were A(H1N1)pdm09 virus.  

• In general, current influenza vaccines tend to work better against influenza A(H1N1)pdm09 and influenza B viruses than against influenza A(H3N2) viruses and preliminary vaccine effectiveness estimates continue to support the use of vaccines. Early data suggests the vaccine are effective and estimates vary  depending on the population studied and the proportions of circulating influenza A virus subtypes (e.g., higher VE in children). See data from Canada, Finland, Hong Kong, Sweden, and the United States.  

• Circulating viruses remain susceptible to neuraminidase inhibitors supporting early initiation of treatment and prophylactic use according to national guidelines.

Flu News Europe, week 5

Via Flu News Europe, an excerpt from its week 5 (January 28-February 3) update:

• Influenza activity is widespread in the European Region and continues to increase. Samples collected from individuals presenting with ILI or ARI to sentinel primary health care sites yielded an influenza positivity rate of 54.7%. 

• Influenza type A virus detections dominated with A(H1N1)pdm09 viruses and A(H3N2) viruses co-circulating. Very few influenza B viruses were detected. 

• Over 50% of specimens from patients hospitalized with severe acute respiratory infection (SARI) collected in week 5/2019 were positive for influenza, and >99% were type A. 

• Pooled data from 22 Member States and areas reporting to the EuroMOMO project indicated excess mortality in a elderly populations overall. However, this result was driven by data from only a few countries.

Flu News Europe: Week 4 update

From Flu News Europe:

Week 4/2019 (21-27 January 2019) 

• Influenza activity continued to increase in the European Region. Samples collected from individuals presenting with ILI or ARI to sentinel primary health care sites yielded an influenza positivity rate of 51.3%. 

• Influenza type A virus detections dominated with A(H1N1)pdm09 viruses and A(H3N2) viruses co-circulating. Very few influenza B viruses were detected. 

• Pooled data from 23 Member States and areas reporting to the EuroMOMO project indicated excess mortality in adults and elderly populations overall. However, this result was driven by data from only a few countries. 

2018/19 season overview  

• Influenza activity in the European region, based on sentinel sampling, exceeded a positivity rate of 10% in week 49/2018 and has increased continuously into week 4/2019. Both subtypes of influenza A viruses are circulating widely, with either A(H1N1)pdm09 or A(H3N2) dominating in some countries, and co-circulation of the two viruses in other countries. Countries should continue to promote vaccination. In addition, countries are encouraged to use antivirals in accordance with national guidelines. 

• In general, current influenza vaccines tend to work better against influenza A(H1N1)pdm09 and influenza B viruses than against influenza A(H3N2) viruses. Preliminary results from Canada where the predominate circulating viruses are influenza A(H1N1)pdm09 viruses, indicate good vaccine effectiveness. These results are supported by recent preliminary vaccine effectiveness results from Hong Kong, where the vaccine was very effective at preventing A(H1N1)pdm09 related hospitalizations in children.

Hong Kong: Early season estimate of influenza vaccination effectiveness against influenza hospitalisation in children

Eurosurveillance has published Early season estimate of influenza vaccination effectiveness against influenza hospitalisation in children, Hong Kong, winter influenza season 2018/19. The abstract:

The winter 2018/19 influenza season in Hong Kong has been dominated by influenza A(H1N1)pdm09 as at January 2019. We enrolled 2,016 children in three public hospitals in Hong Kong between 2 September 2018 and 11 January 2019. Using the test-negative approach, we estimated high early season effectiveness of inactivated influenza vaccine against influenza A or B of 90% (95% confidence interval (CI): 80–95%) and 92% (95% CI: 82–96%) against influenza A(H1N1)pdm09.

Flu News Europe, week 3

Flu News Europe has published its week 3 update. Excerpt:

Week 3/2019 (14-20 January 2019) 

• Influenza activity continued to increase in the European Region. Samples collected from individuals presenting with ILI or ARI to sentinel primary health care sites yielded an influenza positivity rate of 48.8%. 

• Influenza type A virus detections dominated with A(H1N1)pdm09 viruses being more prevalent than A(H3N2). Very few influenza B viruses were detected. 

• Data from the 23 Member States and areas reporting to the EuroMOMO project indicated that generally all-cause mortality was at expected levels for this time of year, but a few countries observed some excess mortality in elderly populations. 

• In Sweden, a seasonal reassortant A(H1N2) influenza virus was detected in a specimen collected at the end of December from an adult. Preliminary whole genome sequence analysis suggests that the virus is a seasonal reassortant containing HA and NS, NP, PA, PB1 and PB2 genes of human seasonal A(H1N1)pdm09 influenza virus and NA genes of human seasonal A(H3N2) influenza virus. No increase in virulence is expected compared to seasonal influenza strains. Further analysis is being conducted by the WHO Collaborating Center on influenza.  More information can be found here. 

2018/19 season overview  

• Influenza activity in Europe is increasing, with both subtypes of influenza A viruses circulating widely. Countries should continue to encourage vaccination. In addition, countries are encouraged to use antivirals in accordance with national guidelines. 

• In general, current influenza vaccines tend to work better against influenza A(H1N1)pdm09 and influenza B viruses than against influenza A(H3N2) viruses. Preliminary results from Canada where the predominate circulating viruses are influenza A(H1N1)pdm09 viruses, indicate good vaccine effectiveness. 

ECDC: Influenza virus characterisation, Summary Europe, December 2018

ECDC has published Influenza virus characterisation, Summary Europe, December 2018. The summary:

This is the third report for the 2018–19 influenza season. As of week 1/2019, 18 049 influenza detections across the WHO European Region had been reported. Detections were made up of 97.7% type A viruses, with A(H1N1)pdm09 prevailing over A(H3N2), and 2.3% type B viruses, with 16 (64%) of 25 ascribed to a lineage being B/Yamagata.