As new strains of COVID-19 emerge, how are vaccine makers responding to virus mutations?

The novel coronavirus disease (COVID-19) is evolving, increasing the need for new vaccines to protect people from severe illness and death.

First case of infection confirmed in Australia Highly transmissible XEC “recombinant” variants — A combination of two previous Omicron variants called KS 1.1 and KP 3.3.

Researchers have been working to ensure that vaccinations that provide adequate levels of protection against new variants of COVID-19 are widely available to communities.

So how do scientists keep track of mutations and update vaccines when there are always new variants?

How is an mRNA COVID-19 vaccine made?

When reports about the coronavirus first emerged, researchers quickly obtained the genome sequence of SARS-CoV-2 (the virus that causes COVID-19).

The National Human Genome Research Institute (NHGRI) said this helped researchers understand the genetic makeup of the virus and how it causes disease in people.

When scientists analyzed the gene sequence, they identified the spike protein as the most effective target for the immune system to make copies, or codes, of it.

Unlike traditional vaccines, which contain an inactivated or weakened version of the virus, mRNA COVID-19 vaccines contain a message or code that is delivered to someone's cells.

Damien Purcell, a professor of virology at the Doherty Institute, said the spike protein's code, or RNA message, is “packaged” in lipids to protect it so it can be distributed in a syringe.

Professor Purcell said that when an mRNA vaccine, or message, is injected into a person's muscles, it tells the cells to reproduce the spike protein.

“These are little bubbles of fat, and four different lipids come together to wrap around the RNA. [and] This allows it to be packaged in a syringe and protected when it is injected into a muscle,” Professor Purcell said.

“These lipids facilitate the uptake and transmission of essential messenger RNA, which is a message encoded within your own cells that causes your cells to…start making the spike protein.”

This process triggers an immune response and produces spike protein antibodies.

These antibodies remain in the body and when someone is infected, they recognize the virus and attack the antigen before it reaches healthy cells, according to NHGRI.

How are vaccines being improved to deal with new strains?

Tony Cunningham, director of the Center for Virus Research at Westmead Medical Research Institute, said the new strain emerged when the spike protein of SARS-CoV-2 changed, making the virus more infectious.

Professor Cunningham said mRNA vaccines allowed scientists to change the code of the spike protein and update the vaccine with new messages.

“If you actually think of RNA and DNA like colored beads on a string (four colored beads that change along the string), you're essentially changing its sequence.” he said.

“That spike protein is what actually allows the virus to attach to cells, and what we want to do is generate antibodies that block the virus from attaching to cells.”

Professor Purcell agreed, saying one of the advantages of mRNA vaccines is that they can usually be modified and manufactured within a month.

“In fact, one of the very powerful aspects of mRNA technology is that so many steps can remain the same,” he said.

Professor Cunningham said the key to responding quickly to new variants was maintaining appropriate surveillance.

He said it was up to the World Health Organization to recommend which strains should be included in the latest vaccines.

Professor Cunningham said the vaccine would need approval from Australia's Therapeutic Goods Authority (TGA) to ensure it was safe and effective, a process that could take around two months.

Why do I need to update my vaccine?

Professor Cunningham said COVID-19 vaccines needed to be updated as they did not effectively protect against new strains of the virus.

He said that's because the immune system doesn't have the same antibodies to recognize and fight off the mutated virus.

“That's why we need to keep changing vaccines and why older people, especially, need to be vaccinated every six months to maintain antibodies.”

Professor Purcell said the original Omicron strain was an “escape” variant that required modern vaccines.

“When the first Omicron came out, it had so many changes, more changes than I've ever seen before, and it was a very significant evasive type,” he said.

“People who received the ancestor strain of the vaccine were not protected from infection by the new coronavirus variant.”

He said people still had some immunity from the initial vaccines, but it wasn't enough.

“We have some basic immunity that can still protect us from severe disease from these infections, but it still makes sense to develop new types of vaccines.” he said.

What vaccines are approved for use in Australia?

According to Australian Department of Health statistics, as of October 9, 72.3 million doses of coronavirus vaccines had been administered.

Pfizer's Omicron XBB. 1.5 and the original vaccine were approved for use in children ages 5 to 11 years, and Pfizer's original vaccine was also available for children ages 6 months to 4 years.

Pfizer's Omicron XBB. 1.5, Original/Omicron BA.4/5, and Moderna's Omicron XBB. According to Healthdirect, 1.5 was available to people 12 years of age and older.

The TGA stated: The JN.1 strain vaccines from Pfizer and Moderna were being evaluated. For use in Australia.