HomeSafetyBird flu, the European Union orders vaccines

Bird flu, the European Union orders vaccines

Avian influenza is a zoonosis that over the years has caused serious problems for animal health and the poultry supply chains involved. Its spread and the 'species jump', recorded in some dairy cattle and in rare cases also in humans, has led to the adoption of safety measures which include, in the European Union, the purchase of vaccines for human use . An in-depth look.

1) Avian influenza, introduction

Bird flu (Avian Influenza, AI) is described by the European Center for Disease Prevention and Control (ECDC) of the European Union as an infectious disease, caused by RNA viruses, which manifests mainly with respiratory signs and symptoms.

The infection It affects and spreads mainly via wild aquatic birds. The strains are divided into high pathogenicity (HPAI, i.e. A/H5, A/H7) and low pathogenicity (LPAI). Some of them have caused sporadic transmission events in humans. (1)

2) Diffusion in Europe

The virus Avian influenza A(H5N1), first identified in southern China and Hong Kong, emerged in 1996 and was found to kill a high percentage of infected poultry.

Its diffusion in Europe, only sporadic in poultry and wild birds until 2021, has since caused the largest outbreaks ever observed in those species (over 50 million birds, in 2022):

- 2014 / 2015. Identification of the A(H5N8) subtype in Europe. Subsequently, this and other subtypes spread throughout the various Member States to the point of triggering real epidemics;

- 2016 / 2017. First identification of A(H5N8) in a wild bird in Hungary, then also in farms in 19 Member States. A(H5N6), in 2017, in poultry in Italy and Hungary;

- 2018. Low levels of A(H5N6) in Finland, Sweden, the Netherlands, Germany, Ireland, the Slovak Republic, the United Kingdom and Denmark. H5N8 outbreaks in poultry in Bulgaria;

- 2019. Confirmation of A(H5N6) in wild birds, strongly related to viruses from previous years. Few outbreaks in poultry, concentrated in Bulgaria;

- 2020. Several outbreaks of A(H5N8) on farms in Poland, the Czech Republic, Germany, Slovakia, Romania and Hungary. Following this, outbreaks extended to H5N5, H5N1 and H5N3 subtypes in wild birds, starting from the Netherlands;

- 2021. Significant improvement in the situation, with some outbreaks concentrated in the summer period among wild birds;

- 2022. H5N1 has broken out in 25 EU member states in wild birds, poultry and other captive birds. Wild marine birds have been among the hardest hit, and it has been difficult to implement virus containment measures for poultry. Especially in France, Italy and Hungary where the outbreaks were more numerous;

- 2023. Spread across 26 Member States, higher number of outbreaks but lower severity. The number of mammalian species identified with the virus, especially H5N1, has increased with particular regard to wild carnivores, fur animals, marine mammals and companion animals (albeit in very rare cases);

- 2023 / 2024. From the second quarter of 2023 the situation improved, but a new epidemic season began in October 2023 with new introductions of the HPAI virus by migratory wild birds (common cranes were the most affected species). (2)

3) Cases of human infection

Ecdc reports that transmission of the A(H5N1) strain from birds to humans is rare, although it can cause serious disease, and no human-to-human transmission has been observed. The A(H7N9) strain, identified in China in 2013, was instead found to be very virulent and lethal in humans, although it is classified as LPAI. Massive vaccinations of poultry have made it possible to contain the risks of infections in humans.

Human health concerns have increased due to the genetic variations that the A(H5N1) strain has undergone over time, the repeated epidemics in wild and domestic birds, the jump in species in some mammals (eg sea lions, minks).

Knowledge of transmission routes, reservoirs, genetic sequence (also following mutations), pathogenesis and other aspects related to the virus are fundamental for the development of prevention tools (i.e. vaccines) and diagnosis, in order to limit potential epidemics or pandemics on humans. (3)

3.1) Recent cases of human infection

WHO (World Health Organization) recorded, between 2003 and May 22, 2024, 891 cases of human infections with avian influenza A (H5N1), including 463 deaths, from 24 countries. Almost all cases are linked to close contact with live or dead infected birds, or to contaminated environments. Despite this, WHO assesses the risk of A(H5) viruses to the general population as 'low', as the transmission capacity and probability of human-to-human spread are low.

3.1.1) Australia

The 22 May 2024 A laboratory-confirmed case of human A(H5N1) infection has been reported to WHO in Melbourne, Victoria. (4) The infection from an unknown source involved a 2-year-old girl, now in good health, returning from a trip to India. Symptoms reported included loss of appetite, irritability, fever and vomiting.

The case caused a particular stir due to the fact that it was the first report recorded in Australia, but also due to the absence (declared by the parents) of the little girl's contact with animals or sick people during her stay in India. Therefore, it is hypothesized that transmission occurred in a contaminated environment.

3.1.2) Mexico

The latest report on zoonoses, ECDC reported the first laboratory-confirmed case of human infection with the A(H5N2) virus in Mexico, the risk of transmission in the EU is considered low (5,6). The man was hospitalized in Mexico City, and died on the same day of hospitalization. Again, the man does not appear to have been exposed to poultry or other animals and the source of the infection is unknown, except that several outbreaks of A(H5N2) in poultry have been reported in Mexico.

The subject he developed fever, shortness of breath, diarrhoea, nausea and general malaise, conditions which had already manifested themselves in the previous period with a three-week bedridden state. There were no cases of human-to-human transmission, as confirmed also in a suspected case that tested negative in an influenza A polymerase chain reaction (PCR) assessment.

3.1.3) United States of America

A worker in contact with presumably infected dairy cattle he contracted infection with the A(H5N1) virus in the USA. It is the second case of avian influenza contracted in the United States by workers exposed to contact with infected mammals. WHO registered the notification on 1 April 2024. (7) Diagnosis of conjunctivitis without development of other pathologies. The infection was not transmitted to relatives or other people with whom the worker came into contact.

Numerous wild birds have been infected since 2022, with sporadic cases in farmed animals (poultry) and mammals, including cats near dairy farms, reported in 50 states or territories. The Centers for Disease Control and Prevention (CDC) in the USA has published the sequences of the identified virus and the genome of the virus in the patient, which presents minor changes compared to animal viruses, in order to help the identification of new cases of A(H5N1 ).

4) Transmission of the virus to other mammals, EFSA report

EFSA (European Food Safety Authority), following the increase in reports of cases of avian influenza on mammals, drafted a report with Enetwild experts on the epidemic potential of the virus, based on a systematic peer review of 76 scientific articles, using the different mammalian species as reservoirs and sources of infection. (8)

The most represented taxa they are included in the order Carnivores, with the risk of infection attributed mainly to predation (or feeding) of infected birds or contact with avian species. Evidence of mammal-to-mammal transmission in nature is only circumstantial and has yet to be confirmed. However, trophic transmission methods must be carefully considered to evaluate the risk of food transmission of the virus, especially modified strains.

Among the subtypes to check, H3N8 and H9N2 were considered the most important due to the greater ease of replication in the cells of the respiratory tracts of mammals (including humans), potentially favoring the spread to humans. Active monitoring and effective surveillance systems in nature and in captivity contexts are recommended to identify mutations and/or modalities that favor the spread of the virus on these species.

5) Monitoring and management of avian influenza in the EU

The Avian Flu is among the diseases subject to EU surveillance programs to be managed according to the general rules of the Animal Health Law. These provide specific rules for prevention and control, together with surveillance and eradication programmes, the adoption of emergency measures in the event of outbreaks, and the implementation of emergency prophylactic vaccinations. (9)

IZS – the Venice Zooprophylactic Institute it is the Union Reference Laboratory (EURL), the national reference center for avian influenza, as well as the reference laboratory of the World Organization for Animal Health (WOAH). (10) IZS has developed a system for reporting total cases of avian influenza notified by WHO Member States, in relation to commercial poultry flocks, backyard flocks, other captive birds and wild birds. (11) ECDC, on the other hand, publishes weekly reports on zoonoses.

EFSA has in turn developed a tool aimed at facilitating both the prediction of outbreaks of avian influenza epidemics and the adoption of early warnings to allow the various Member States to adequately manage the risks. The 'Migration Mapping Tool' allows you to evaluate data on the abundance, distribution and movement of wild birds, while the 'Bird Flu Radar' lays the foundations for adopting different measures, also extended to farms. (12)

6) WOAH, monitoring and management

WOAH – World Organization for Animal Health – included avian influenza in the list of diseases subject to monitoring and management.

6.1) Monitoring

The 183 member states WOAH must report the following cases of infection:

– highly pathogenic avian influenza viruses, regardless of their subtypes, detected in birds (domestic and wild);

– birds other than poultry, including wild birds, with highly pathogenic influenza A virus;

– domestic and captive wild birds with low pathogenic avian influenza viruses which have been demonstrated to be naturally transmitted to humans, associated with serious consequences. (13)

On a voluntary basis, WOAH member states may report cases of low pathogenic avian influenza (LPAI) in wild birds, as well as declare the absence of avian influenza on the territory or reference area.

6.2) Management

Management of avian influenza by WOAH is provided for in its Terrestrial Code and Terrestrial Manual which provide, in addition to the specific measures to be adopted for the management of this disease, the compartmentalization measures to be adopted (in replacement or complement to regionalization) as a biosecurity measure.

The compartmentalization, as seen in the case of African swine fever, is certainly more effective in guaranteeing quicker solutions that do not compromise production and trade.

WOAH and FAO they launched the OFFLU network together, in order to:

  • promote the exchange and research of data and biological material (including viral strains) to facilitate the dissemination of knowledge by researchers and veterinary authorities, and
  • adopt prevention, diagnosis, surveillance and control plans. For example, an FAO warning has been spread online about avian influenza which may arise during poultry trade before and during the Lunar New Year holidays in Asia. (14) WHO, in turn, offers a weekly update on cases of avian influenza in humans. (15)

7) European Union, supply of vaccines for humans

The European Commission, through its Health Emergency Preparedness and Response Authority (HERA), has signed on behalf of Member States a joint procurement framework contract for the supply of 665.000 doses, up to 40 million doses over 4 years, of the vaccine 'anti-pandemic' Zoonotic Influenza Vaccine Seqirus, to be targeted at people most exposed to potential transfers of avian influenza from birds or animals, such as poultry farmers and veterinarians. (16)

CSL Seqirus UK is the manufacturer of the biological active ingredient of the vaccine, and is part of the CSL group, of Australian origin.

Information about the vaccine, whose authorization (recently modified) is held by the Italian branch, are available on the Union register of medicinal products, from which it is possible to verify all the information on the product. (17)

WOAH consider vaccination as a fundamental tool for preventing a possible avian influenza pandemic. In cooperation with WHO it has also developed recommendations for the pharmacological management of people infected with A(H5N1) and the exchange of epidemiological information aimed at developing effective vaccines (18,19,20).

8) Provisional conclusions

The evolution of avian influenza highly pathogenic, it represents a serious risk for the livestock sector and for the health of wild birds.

The adoption of preventive measures, which include the vaccination of farm animals, is indicated by WOAH as the necessary and essential strategy to guarantee animal health and continuity in the production and trade of poultry and related products. (21)

Perplexities remain on the European Commission's choice to purchase millions of doses of vaccines for human use, after the 'health dictatorship' of uncertain outcome imposed under Covid.

Dario Dongo and Andrea Adelmo Della Penna

Footnotes

(1) See https://www.ecdc.europa.eu/en/avian-influenza

(2) See https://food.ec.europa.eu/animals/animal-diseases/diseases-and-control-measures/avian-influenza_en

(3) Charostad J. et al. (2023) A comprehensive review of highly pathogenic avian influenza (HPAI) H5N1: An imminent threat at doorstep. Travel Medicine and Infectious Disease 55:102638, https://doi.org/10.1016/j.tmaid.2023.102638

(4) Disease Outbreak News. Avian Influenza A (H5N1) – Australia. 7.6.24 https://www.who.int/emergencies/disease-outbreak-news/item/2024-DON519

(5) See https://www.ecdc.europa.eu/sites/default/files/documents/Communicable-disease-threats-report-week-23-2024.pdf

(6) Disease Outbreak News – Avian Influenza A (H5N2) – Mexico. 5.6.24. https://www.who.int/emergencies/disease-outbreak-news/item/2024-DON520

(7) Disease Outbreak News – Avian Influenza A (H5N1) – United States of America. 9.4.24. https://www.who.int/emergencies/disease-outbreak-news/item/2024-DON512

(8) Enetwild Consortium et al. (2024) The role of mammals in Avian Influenza: a review. EFSA Supporting Publications 21(3):8692E, https://doi.org/10.2903/sp.efsa.2024.EN-8692

(9) The reference regulations are Reg. (EU) 2016/429; Delegated Reg. (EU) 2020/687; Delegated Reg. (EU) 2020/689; Implementing Reg. (EU) 2020/690, the Reg. delegate (EU) 2023/361, and implementing decision (EU) 2023/2447.

(10) See https://www.izsvenezie.it/istituto/centri-di-referenza/influenza-aviaria-e-malattia-di-newcastle/

(11) See https://eurlaidata.izsvenezie.it/epidemio.php

(12) See https://app.bto.org/mmt/avian_flu_map/avian_flu_map.jsp. Select the 'Migration Map' cursor to switch to the Migration Mapping Tool.

(13) See https://www.woah.org/en/disease/avian-influenza

(14) FAO. FAO alert on avian influenza – risk of upsurge and regional spread through increased poultry trade prior to and during Lunar New Year festivities in Asia. https://openknowledge.fao.org/handle/20.500.14283/cc9524en

(15) WHO. Avian Influenza Weekly Update 2024. https://iris.who.int/handle/10665/375483

(16) European Commission. Commission secures access for Member States to 665,000 doses of zoonotic influenza vaccines to prevent avian flu. 11.6.24. https://ec.europa.eu/commission/presscorner/detail/en/ip_24_3168

(17) See https://ec.europa.eu/health/documents/community-register/html/h1761.htm

(18) WHO (2006) WHO rapid advice guidelines on pharmacological management of humans infected with avian influenza A (‎H5N1)‎ virus. https://iris.who.int/handle/10665/69373

(19) Schünemann HJ et al. (2007) WHO Rapid Advice Guidelines for pharmacological management of sporadic human infection with avian influenza A (H5N1) virus. Lancet Infect Dis. 7(1):21-31, https://doi.org/10.1016/S1473-3099(06)70684-3

(20) WOAH. Influenzas with zoonotic potential: the contribution of the animal health sector for pandemic preparedness. 15.5.22. https://www.woah.org/en/influenzas-with-zoonotic-potential-the-contribution-of-the-animal-health-sector-for-pandemic-preparedness/

(21) WOAH. Avian influenza vaccination: why it should not be a barrier to safe trade. https://www.woah.org/en/document/avian-influenza-vaccination-why-it-should-not-be-a-barrier-to-safe-trade/

Andrea Adelmo Della Penna

Graduated in Food Technologies and Biotechnologies, qualified food technologist, he follows the research and development area. With particular regard to European research projects (in Horizon 2020, PRIMA) where the FARE division of WIISE Srl, a benefit company, participates.

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