Monday, October 18

How are Covid vaccines produced and why have there been delays? | Vaccines and immunizations


When the first Covid-19 vaccines were approved in the UK and elsewhere three months ago, many thought that the end of the pandemic was almost within reach.

However, few had anticipated the enormous logistical problems involved in mass production and the supply of billions of doses around the world. This has been underscored by high-profile political disputes between the UK and the EU over who should receive which vaccine deliveries from which factories amid dose shortages.

When the UK announced an imminent reduction in its own vaccine supply, we took a look at what’s behind the robberies.

Mass production of new vaccines is complicated

There have been two broad approaches to large-scale production of Covid vaccines. The Oxford / AstraZeneca jab is based on a widely proven approach in which lab-grown cell cultures are produced in large bioreactors, a bit like brewing, but for vaccines.

The second, newer technique, which produces mRNA vaccines like Pfizer and Moderna injections, involves culturing a modified peak protein in the lab and then combining it with enzymes and nucleotides before being packaged into tiny fatty bubbles.

Each technique has its own problems when it comes to increasing mass production.

What are the problems with Oxford-style shots?

Typically, a vaccine production facility like the one in Oxford can take six to nine months to get up and running, although in this case it has been faster. The biggest problem is with the so-called yields, which depend on the health of the underlying cell culture. Any quality control issues, for example related to temperature, humidity or compromised sterility, can lead to fewer vaccines at the end of the process, a problem that has been observed in some AstraZeneca production facilities throughout the world.

While you might expect more or less identical production facilities to produce the same amount of vaccine, in fact, yields can vary wildly, up to an order of three, especially in a new production process, which experts say is both a “art”. as science ”.

What about Pfizer-style vaccines?

While mRNA vaccines are somewhat simpler to produce and much less vaccine is needed to produce a strong antibody response, the novelty of the technology means that key ingredients such as fat bubbles and nucleotides needed for ” bovine soup “, have been scarce.

And while vaccine manufacturers of both types have tried to scale rapidly, there has also been a shortage of manufacturing facilities for sites that must be built to the highest biosafety standards.

One problem is that some manufacturers supplying key elements needed for such vaccines have waited for the new jabs to advance in development before risking committing to increasing their own production.

A recently reported example is the giant disposable plastic bags used as sterile liners inside bioreactor tanks for the Pfizer, Moderna and Novavax vaccines, which have become a production bottleneck at the EU and elsewhere.

The bags are produced by a small number of suppliers, and vaccine producers have struggled to obtain them, prompting Merck to recently announce that it would expand its facilities to remove this choke point.

Shouldn’t someone have anticipated all of this?

Some people did, including Bill Gates, who wrote as early as last April that the scale of the pandemic meant that facilities had to be built to specification. But while organizations like Gavi, the global vaccine alliance, and some governments invested in vaccine research and production facilities, there have been notable shortcomings in global readiness that have created bottlenecks and sparked a fight over vaccine shortages.

More generally, some experts say that the pharmaceutical industry, while huge, is not structured for the kind of integrated global effort required to produce billions of doses of vaccines on short notice, including manufacturing supplies for filling. and the finish, such as glass vials. many of which come from a handful of countries, including India and China.

Is there a pattern here?

Liz Breen, a University of Bradford academic who studies healthcare operations, including supply chains, thinks so. “The effort to create new vaccines has been amazing, but along the way it is as if some of the fundamentals have fallen by the wayside: the bread and butter that makes scaling possible,” he said. “I really think people were so focused on vaccines, they didn’t think any more about what needs to come with them to make it happen.”

What about vaccine nationalism?

With so many countries chasing underdoses, vaccine nationalism has become a real problem with threats of restrictions on the export of finished vaccines and raw materials. The UK has now got it wrong due to a temporary shortfall in deliveries of the Serum Institute of India’s Oxford vaccine, which has been contracted to produce it. Since most vaccines require two doses administered within a finite period, this has a knock-on effect for vaccination programs.


www.theguardian.com

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