How are Covid vaccines made 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 the end of the pandemic was almost imminent.

Few, however, had anticipated the major supply problems involved in mass production and delivery of billions of doses worldwide. This is reinforced by the high-profile political squares between the UK and the EU over who should find out which vaccines factories are producing amid a shortage of doses.

As the UK announced an imminent pressure on their own vaccine supply, we looked at what lies behind the holdups.

Mass production of the new vaccines is complex

There have been two broad approaches to the mass production of Covid vaccines. Oxford / AstraZeneca injection relies on a largely well-proven procedure in which laboratory-performed cell cultures are produced in large bioreactors – a bit like distillation, but for vaccines.

The second newer mechanism, extracting mRNA vaccines such as the Pfizer and Moderna jabs, involves modified spike proteins to be cultured in the laboratory and then combined with enzymes and nucleotides. before being packed into tiny bubbles.

Each invention has its own issues when it comes to increasing mass production.

What matters Oxford-style vaccines?

A vaccine production facility like Oxford’s usually takes six to nine months to proceed, although in this case it has been faster. The biggest question is with a so-called product, which is responsible for the health of the cell culture. Any quality control issues – for example related to temperature, humidity or associated sterility – can lead to less vaccination at the end of the process, an issue that has been observed at some AstraZeneca production facilities around the world .

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

And with Pfizer-style vaccines?

Although mRNA vaccines are in some ways simpler to produce and require much less vaccination to produce a strong antibody response, the novelty of the technology means that key ingredients – such as the fat bubbles and nucleotides necessary for “vaccine soup” – have been scarce.

And while both types of vaccine manufacturers have tried to expand rapidly, there is also a shortage of manufacturing facilities for sites that need to be built to the highest biosecurity standards.

One issue is that some manufacturers who supply key elements needed for such vaccines have waited for the new jobs to progress in their development before taking the risk of promising the increase own output.

One recently reported example is the large disposable plastic bags used as sterile liners inside bioreactor tanks for the Pfizer, Moderna and Novavax vaccines, which have emerged as bottles in EU production and elsewhere.

The bags are made by a small number of suppliers, and vaccine manufacturers have been struggling to find them, prompting Merck to recently announce that he would expand his resources to eliminate this chokepoint.

Shouldn’t someone expect this?

Some people, including Bill Gates who wrote as far back as April last year, argued that the scale of the pandemic meant that facilities had to be built on spec. But while organizations such as Gavi, the global vaccine alliance, and some governments have invested in vaccine research and production facilities, there have been obvious shortcomings in global preparation that has created bottles and led to a crackdown on scarce vaccines. .

More broadly, some experts say the pharmaceutical industry, while huge, is not structured for the kind of unified global effort needed to produce billions of doses of vaccine without warning, including the manufacture of materials for their filling and finishing, such as glass filters, many of which are obtained from a small number of countries including India and China.

Is there a pattern here?

Liz Breen, an academic at Bradford University who studies health activity involving supply chains, believes that. “The drive to create new vaccines has been amazing, but along the way it’s as if some of the basics have fallen apart – the bread and butter stuff that makes scaling possible,” he said. i. “I really think people were so focused on the vaccines, they never thought about what needs to come with it to happen.”

What about vaccine nationality?

With so many countries running enough doses, vaccine nationality has become a real issue with threats of restrictions on the export of finished vaccines and raw materials. The UK is now mistaken for a temporary shortage in the delivery of the Oxford vaccine from the Serum Institute of India, which was hired to implement it. With most vaccines requiring two doses to be delivered within a set time limit, this has an impact on vaccine programs.