Considerations for use of avian #influenza #H5 #vaccines during the #interpandemic and emergence periods

Report of a WHO virtual scientific consultation, September 2024

© World Health Organization 2025 Some rights reserved. This work is available under the Creative Commons AttributionNonCommercial-ShareAlike 3.0 IGO licence (CC BY-NC-SA 3.0 IGO; https://creativecommons.org/licenses/by-nc-sa/3.0/igo).

Executive summary

Avian influenza viruses – particularly A(H5) – pose a significant risk for potential pandemics as they can infect humans and other mammals.

The high mutation rate of influenza viruses raises concerns about their potential to adapt for efficient human-to-human transmission.

Influenza vaccines are crucial tools in mitigating the impact of influenza epidemics and pandemics.

Given the global circulation of A(H5) viruses – especially the spillover to dairy cattle since early 2024 – and the rapidly evolving vaccine landscape, the World Health Organization (WHO) held a virtual scientific consultation on 12–13 September 2024 to review:

-- the current global A(H5) epidemiological situation;

-- the availability and landscape of A(H5) vaccines and their characteristics;

-- updated evidence on A(H5) vaccine immunogenicity, safety and other characteristics;

and

-- considerations for the use of A(H5) vaccines, based on expert opinions.

The consultation did not discuss:

-- A(H5) vaccine stockpiles;

-- A(H5) vaccine regulatory approvals or access issues;

-- mathematical modelling to inform options for use of A(H5) vaccines in the context of other public health measures and stockpiles;

-- acceptance, cost, cost–effectiveness, risk–benefit ratios or other programmatic considerations;

-- strategies for animal A(H5) vaccination.

Topics such as equity were also not discussed, as the Pandemic Influenza Preparedness Framework has enabled WHO to make significant progress in preparing for equitable access to vaccines.

The primary objective of the virtual scientific consultation was to update WHO’s Options for the use of human H5N1 influenza vaccines and the WHO H5N1 vaccine stockpile, which was developed during a previous scientific consultation on A(H5N1) held in October 2007.

The participants in the 2024 consultation included:

-- experts from research academia, WHO collaborating centres and essential regulatory laboratories of the Global Influenza Surveillance and Response System,

-- experts from countries,

-- the WHO Strategic Advisory Group of Experts (SAGE) Secretariat,

-- industry associations and other partners.

This report summarizes the outcomes of the virtual scientific consultation, and is expected to be used during the potential update of SAGE recommendations on the use of licensed H5N1 vaccines.

The A(H5) vaccine landscape included in this report is up to date as of 31 March 2025.

A(H5) viruses pose a threat to human and animal health globally. National, regional and global preparedness is needed urgently.

Countries should remain vigilant in conducting surveillance for emerging influenza viruses with pandemic potential.

WHO will continue to monitor the situation and provide updated risk assessments, guidance and technical support, where needed.

(...)

Source: World Health Organization, https://www.who.int/publications/i/item/9789240111462

____

#Neuroinvasive #Oropouche virus in a patient with #HIV from extra-Amazonian #Brazil

{Excerpt} A novel reassortant Oropouche virus (OROV) lineage (with medium [M], large [L], and small [S] RNA segments : M1L2S2) has driven Brazil's largest and most geographically widespread OROV epidemic , expanding beyond the endemic Amazon basin to establish local transmission across multiple Brazilian states and other previously unaffected Latin American countries . The rapid spread of this lineage underscores its evolutionary potential and reinforces its significance as a public health threat .1 Similar to chikungunya and Zika viruses, expanding arboviruses can exhibit unexpected clinical and epidemiological shifts , including vertical transmissions , neuroinvasive effects, and potentially fatal outcomes.2–4 Although OROV typically causes self-limited febrile illness, accumulating clinical and experimental evidence suggests neurotropic potential .5 This Correspondence describes the first confirmed case of neuroinvasive OROV infection caused by the emergent M1L2S2 lineage in ext...

Stability of #influenza viruses in the #milk of #cows and #sheep

Abstract In late 2023, H5N1 high pathogenicity avian influenza (HPAIV) started circulating in dairy cattle in the USA . High viral titres were detected in milk from infected cows , raising concerns about onwards human infections . Although pasteurisation was shown to effectively inactivate influenza viruses in milk, unpasteurised milk still poses a risk of infection, both from occupational exposure in dairies and from the consumption of raw milk. We therefore assessed how long influenza viruses could remain infectious for in milk without heat inactivation. We examined the stability of a panel of influenza viruses in milk , including a contemporary H5N1 HPAIV and a variety of other influenza A and D viruses. We incubated viruses in cows' milk under laboratory conditions : at room temperature to simulate exposure in dairies and at 4°C to simulate exposure to refrigerated raw milk. Following an isolated report of H5N1 viral RNA being detected in milk from a sheep in the UK , we also c...

#Evidence of #Viremia in Dairy #Cows Naturally Infected with #Influenza A {#H5N1} Virus, #California, #USA

Abstract We confirmed influenza A virus (IAV) by PCR in serum from 18 cows on 3 affected dairy farms in California, USA . Our findings indicate the presence of viremia and might help explain IAV transmission dynamics and shedding patterns in cows. An understanding of those dynamics could enable development of IAV mitigation strategies. Source: US Centers for Disease Control and Prevention, https://wwwnc.cdc.gov/eid/article/31/7/25-0134_article ____

ETIDIOH - NEW

Search This Blog