Adjuvants and the new crown vaccine


Aluminum salt, put into use in 1926
Scientific terms: aluminum hydroxide, aluminum phosphate

In the United Kingdom in the 1970s, there was a fierce debate about the possible effects of aluminum salts in pertussis vaccines on the nervous system. But even so, in the past 100 years, aluminum salts are still the main source of vaccine adjuvants. Nowadays, among all kinds of new crown vaccines, the vaccine developed by China Kexing Biological contains aluminum salt.


Horseshoe crab blood, put into use in 1977
Scientific term: American horseshoe crab reagent

Horseshoe crab blood is the blood of horseshoe crabs. It is very precious and can protect the human body from bacteria. The American horseshoe crab reagent extracted from it began to be used in large-scale vaccine production in 1977, and its harmlessness has also been verified. In order to avoid endangerment or even extinction of horseshoe crab species, biologists adopted a partial extraction method for the American horseshoe crab reagent. The Swiss pharmaceutical company Lonza Group used a small amount of American horseshoe crab reagent in the development of Modena’s new crown vaccine. Due to the popular alternative use of synthetic limulus factor C, horseshoe crabs are currently protected. The US Pharmacopoeia Commission has been studying the application of this ingredient in the new crown vaccine since May last year, and Europe also introduced the alternative ingredient on January 1 this year.


Cod liver oil, put into use in 1997
Scientific term: Squalene

Cod liver oil is the fat extracted from the liver of sharks and cod, which is rich in squalene. The new crown vaccine developed by GlaxoSmithKline of the United Kingdom, Sequirus of Australia and China Clover Biopharmaceutical Company all use squalene adjuvants. Many veterans who participated in the Gulf War experienced discomfort after being vaccinated against anthrax. Squalene was suspected to be the culprit, but its harmlessness was later confirmed. Since 1997, squalene has been used in anti-flu injections. In addition, squalene is also present in the human body and a variety of animals and plants (such as olives, sugar cane, etc.), but it is far less than its content in sharks. The doubling of industry demand for squalene has caused strong anxiety in the Shark Alliance, a shark conservation organization. As Kukui Joan, professor of molecular microbiology at the London School of Hygiene and Tropical Medicine, said: “At present, there is no successful synthesis of any substance that can replace squalene.”


Soap bark, put into use in 2017
Scientific term: saponin

Long ago, the soap bark tree was used by humans to make soap. Saponin is extracted from the bark of Quillaja saponaria. Its effect is similar to that of immunostimulants and can reduce the number of antigens used in vaccines. Saponin was discovered as early as 1925, but it was not until 1964 that people began to formally study its effects. In 2017, this substance was successfully used by GlaxoSmithKline in the United Kingdom in its Xin’an Lishi vaccine (shingles vaccine). The new crown vaccine developed by Novavax Biotechnology Pharmaceuticals in the United States also uses this ingredient and has entered the final clinical trial stage. As saponin has become more widely used, its demand has surged. The saponaria tree mainly grows in central Chile. The over-development of the pharmaceutical and daily chemical industries and climate change have seriously threatened the survival of this tree species. In response to unexpected needs, the Chilean government has decided to plant saponaria in large quantities, but is this enough to protect this ancient species that has survived on the earth for 20 million years?


Nano fat, put into use in 2018
Scientific term: lipid nanoparticles

Lipid nanoparticles were first used in gene therapy drugs for a rare disease (i.e. Onpattro lipid complex) in 2018. In Pfizer-BioNTech and Modena’s new crown vaccine, lipid nanoparticles encapsulate and protect the fragile genetic instructions that trigger the immune response and deliver them to the interior of the immune system cells. In order to prevent the degradation of such tiny oily droplets, frozen storage is required. Stefan Randall, head of Evonik’s industrial product research and development department, said: “Lipid nanoparticles are used to deliver messenger RNA. But in terms of the current scale of vaccine production necessary to deal with the new crown epidemic, lipids The market has felt unprecedented pressure.”


Salmonella, under study
Scientific term: Flagellin

The development of genetics has opened up new prospects for the development of new vaccine adjuvants. Even though flagellin has not been used in human vaccines, the prospects for research on it are still very bright. The future research goal is: respiratory viruses (such as influenza viruses, new coronaviruses, etc.) can cause an immune response as soon as they are imported into the human body to prevent their further spread in the body.