A new pandemic

As we discussed two days ago, in UK Joint Taskforce Policy Paper: Vaccination of Birds Against HPAIV (bird flu) - while a handful of countries have embraced poultry vaccination against avian flu - most countries remain hesitant to move in that direction over safety and international trade concerns.

Poorly matched, or improperly deployed vaccines could help drive viral evolution.  And without rigorous DIVA  testing, infected (albeit, asymptomatic) birds could enter the food chain. 

Despite these concerns, research into poultry avian flu vaccines continues in many countries, including here in the United States (see Zoetis Receives Conditional License from USDA for Avian Influenza Vaccine). 

The decision of whether or when to actually use these vaccines here in the United States continues to be debated. 

In 2023, the Netherlands - after determining that two (of 4) vaccines appeared effective against the newer clade of H5N1 - began the 1st phase of the field trial (see WUR press statement below). 

First chickens in test phase vaccinated against bird flu virus 

September 18, 2023

The first jab was given: 1800 day-old chicks received a vaccination against highly pathogenic H5N1 bird flu. Never before have chickens in the Netherlands been vaccinated against bird flu in a field trial. This marks the start of this field trial, which is taking place on behalf of the Ministry of Agriculture, Nature and Food Quality (LNV). It is an important step toward large-scale vaccination of poultry against the bird flu virus.

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The trial on the two farms will last until the third quarter of 2025. First results are expected in the second quarter of 2024. Under field conditions, the effectiveness of a vaccine may differ from controlled conditions in a laboratory. For example, at a poultry farm, the housing and barn climate are different, the animals are vaccinated against more diseases, and there are other germs present in that could influence the effectiveness of a vaccine. It is important that the vaccines not only provide protection against disease symptoms, but mainly prevent the spread of the bird flu virus.

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While that trial appears to be still ongoing, early results were promising enough that a second phase test has begun in the Netherlands.  This one is expected to run until early 2027. 

(translated)

Start pilot vaccinate poultry against bird flu

News item | 10-03-2025 | 08:00

The pilot for the vaccination of poultry against bird flu has started. After a successful 1st phase of the field trial, this important step can now be taken. Minister Femke Wiersma (LVVN) and the poultry sector are working together to enable large-scale vaccination in a responsible manner. Vaccination plays an important role in significantly reducing the risk of bird flu outbreaks in poultry, which contributes to better protection of both animal and public health.

Minister Wiersma (LVVN): “I am pleased that the poultry sector wants to take this step with me. Vaccination offers a huge opportunity to better control bird flu. With this pilot we take an important step towards a responsible and large-scale use of vaccination. ”

Purpose and approach

The pilot is an essential step in gaining practical experience with vaccination. The aim is, on the one hand, to investigate how the market responds to the sales of the products and, on the other hand, to gain experience with the implementation of the surveillance program. This program ensures that any contamination on a vaccinated farm is quickly detected.

The pilot runs until early 2027 and starts on 1 poultry farm, with possible expansion to several companies. Chicks are vaccinated in the hatchery and are eventually placed on a laying farm as laying hen. The eggs of these hens are only sold within the Netherlands, so that trade with 3rd countries is not hindered.

Step-by-step introduction

Large-scale vaccination requires a step-by-step approach. A direct large-scale introduction requires the expansion of the veterinary infrastructure and the well-organized marketing of the products. In addition, this can have significant trade consequences, necessitating additional trade agreements. That is why the Ministry of LVVN opts for a gradual introduction, so that both effectiveness and economic impact can be properly monitored.

This pilot is being looked at with interest by other countries. The Netherlands is committed to broad international acceptance of vaccination against bird flu, so that Dutch poultry farms are better protected against future outbreaks.

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The track record of poultry vaccination around the globe has been checkered at best.  China's H5+H7 emergency vaccination campaign in 2017 effectively halted their H7N9 epidemic in its 5th year, but other campaigns have been less successful (see J. Virus Erad.: Ineffective Control Of LPAI H9N2 By Inactivated Poultry Vaccines - China).

Given the growing endemicity of H5 viruses in both Europe and the Americas, vaccines may be the only logical recourse.  

But this is not a fire-and-forget solution.  Once we go down that path, we must truly commit to continually updating vaccines, applying them properly, and rigorously test flocks for `breakthrough' infections. 

Anything less, and we risk making a bad problem worse. 

Update 5 February 2025

In 2025, there have been 26 cases of measles reported by Municipal Public Health Services (GGDs) in various regions of the Netherlands. Most involve patients who contracted measles in another country, and their contacts (who are often unvaccinated). There is no national outbreak of measles at this time.

In 2024, there were more than 200 reported cases of measles in the Netherlands in total. There were four larger clusters, each of which gradually subsided. This is because the majority of the Dutch population is protected against measles – either by vaccination, or because they have already had measles.