H5N1

Flu News Europe, week 40

An excerpt from Flu News Europe:

Week 40/2019 (30 September– 6 October 2019) 

• This is the first weekly report for the 2019–2020 influenza season. 

• Influenza activity was low throughout the European Region. Influenza viruses were detected sporadically in specimens from persons with respiratory illness presenting to medical care. 

• Both influenza A and B type viruses were detected. 

• For week 40/2019, data from the 21 countries or regions reporting to the EuroMOMO project indicated all-cause mortality to be at expected levels for this time of the year. 

2018/19 season overview  

• As is usual for this time of year, influenza activity is low in the European Region. 

• During the influenza Vaccine Composition Meeting for the southern hemisphere 2020 season, held in September 2019, WHO recommended the A(H1N1)pdm09 component to be an A/Brisbane/02/2018 (H1N1)pdm09-like virus, the A(H3N2) component an A/South Australia/34/2019 (H3N2)-like virus and the B/Victoria-lineage component to be a B/Washington/02/2019-like virus. The B/Yamagata-lineage component, included only in quadrivalent vaccines is a B/Phuket/3073/2013-like virus. The full report can be found here.

ECDC: Influenza virus characterisation, September 2019

ECDC has published Influenza virus characterisation, September 2019. The executive summary:

Since the July 2019 characterisation report1, a further three shipments of influenza-positive specimens from EU/EEA countries were received at the London WHO CC, the Francis Crick Worldwide Influenza Centre (WIC). A total of 1 511 virus specimens, with collection dates after 31 August 2018, have been received.  

The 85 A(H1N1)pdm09 test viruses characterised antigenically since the last report showed equivalent good reactivity with antisera raised against both the A/Michigan/45/2015 2018–19 vaccine virus and the A/Brisbane/02/2018 2019–20 vaccine virus. The 613 test viruses with collection dates from week 40/2018 genetically characterised at the WIC, including two H1N2 reassortants, have all fallen in subclade 6B.1A, defined by S74R, S164T and I295V HA1 substitutions; 564 of these viruses also have HA1 S183P substitution, often with additional substitutions in HA1 and/or HA2.  

Since the last report, 37 A(H3N2) viruses successfully recovered had sufficient HA titre to allow antigenic characterisation by HI assay in the presence of oseltamivir; all were poorly recognised by antisera raised against the vaccine virus, egg propagated A/Singapore/INFIMH-16-0019/2016. Of the 505 viruses with collection dates from week 40/2018 genetically characterised at the WIC, 399 were clade 3C.2a (with 43 3C.2a2, 17 3C.2a3, eight 3C.2a4 and 331 3C.2a1b); 106 were clade 3C.3a.  

Ten B/Victoria-lineage viruses have been characterised in this reporting period. All recent viruses have HA1 amino acid substitutions of I117V, N129D, and V146I compared to B/Brisbane/60/2008 (clade 1A), a previous vaccine virus. Groups of viruses defined by deletions of two (Δ162-163, 1A(Δ2)) or three (Δ162-164, 1A(Δ3)) amino acids in HA1 have emerged, with the Δ162-164 group having subgroups of Asian and African origin. These virus groups are antigenically distinguishable by HI assay. Of 20 viruses from EU/EEA countries this season that have been characterised genetically, one has been clade 1A, two 1A(Δ2) and 17 1A(Δ3) (16 African and one Asian subgroup).   

Nine B/Yamagata-lineage viruses have been characterised antigenically in this reporting period, giving a total to 23 for the 2018–19 season. All have HA genes that encode HA1 amino acid substitutions of L172Q and M251V compared to, but remain antigenically similar to, the vaccine virus B/Phuket/3073/2013 (clade 3) recommended for use in quadrivalent vaccines for the next northern hemisphere influenza season. 

Flu News Europe, week 12

Flu News Europe has published its week 12 (March 18-24) update. Excerpt:

• Of 45 countries reporting on geographic spread only 11, located in northern, southern, and western areas of the European Region, reported widespread activity. Specimens collected from individuals presenting with ILI or ARI to sentinel primary health care sites yielded an influenza virus positivity rate of 38%, similar to the rate of 39% in the previous week. 

• Of 45 countries reporting on intensity, 41 reported baseline or low intensity. No countries reported high intensity levels. 

• Influenza type A virus detections dominated with more A(H3N2) than A(H1N1)pdm09 viruses among sentinel and non-sentinel source specimens. Few influenza B viruses were detected. 

• Of the specimens from patients with severe acute respiratory infection (SARI) collected in week 12/2019 that were tested for influenza viruses, 21% were positive 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 has returned to normal levels.

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.