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Even the basic idea of Leiber is sustainable: Leiber refines brewers‘ yeast (Saccharomyces cerevisiae) into innovative products for humans and animals. For our customers we conduct research in our own laboratories and develop tailor-made solutions for healthy nutrition, biotechnology and agricultural applications. We reliably supply excellent products – and have been upcycling at world market level since 1954. Give Yeast a Second Life.

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We have been upcycling at world-market level since 1954 and keeping the environment and climate in mind.

Highly Pathogenic Avian Influenza

Administration Is Complex And Costly

Even once you have a working vaccine, injecting thousands of birds individually is no simple matter. It requires trained personnel who can make a subcutaneous injection without having the needle poke out the other side of the skin. Such a skill- and labourintensive task will necessarily be expensive. For some types of vaccines, birds will need boosters — requiring a second round of injections – in order to benefit from full immunity. And indeed, having people from outside the farm come in to vaccinate provides a potential point of entry for the very virus that the establishment is trying to keep down. While these challenges are not insurmountable, this does make vaccines that can be deployed through other means, including in ovo that much more valuable, and it is a non-negligible concern if vaccination is to be envisaged in places with weak veterinary health systems.

Previous Exposure Can Limit Effectiveness

The immunological situation of the birds can also affect their reaction to a vaccine, and thus that vaccine’s effectiveness. For example, as previously mentioned, you cannot give a killed vaccine to a day-old chick whose immune response will not be sufficiently developed to respond to it. Maternal antibodies can also decrease the immune response, and with a viral vectored vaccine, the influence of maternal antibodies will differ depending on the various viral vectors being used. “That’s why you would need to understand the flock you’re working with, [to understand] whether you can use [a particular vaccine] or not,” Dr. Swayne observed.

Silent Circulation

Thus, for a variety of reasons — whether because the vaccine was poorly matched to the strain that was circulating, or because the birds had antibodies that impacted its ability to react as it should have to the vaccine and thus develop an immunity to HPAI, or because the vaccine was administered incorrectly — HPAI vaccines may end up being only partially effective.

That’s a major problem, because if a vaccine suppresses symptoms but does not stop the spread of HPAI, then then you’ve still got virus circulating and you’re not always aware of it. Such a dynamic can make the HPAI situation in an area much worse, as explained by two Wageningen Bioveterinary Research experts in a 2019 article by Dutch animal health magazine Tijdschrift voor Diergeneeskunde 14

“Are we seeing evolutions in opinions regarding HPAI vaccination in developed countries?” In Europe, at least, the experience with HPAI over the last few years has changed the thinking. Early this year, the European Commission harmonized its rules for the use of vaccines in order to prevent or control animal diseases. The move was explicitly a response to the HPAI situation, and allows for the movement of animals and products from establishments and zones where vaccination has taken place.

At a member-state level, the Dutch Ministry of Agriculture, in addition to commissioning trials to identify an effective H5N1 vaccine, is also working on preparations for an HPAI vaccination program for poultry in the Netherlands, starting at a pilot scale and working up to a larger scale. In Minister Adema’s words, his own country and France are the two European states leading the way in the vaccination process.15 In France, the validation of a vaccination plan is expected in May, and the country may begin vaccinating as of September, according to the calendar for the vaccination action plan posted by the French Ministry of Agriculture in early 202316

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