What the new variants mean for the future of Covid-19 vaccines
"I think this is one of the biggest advantages of the messenger RNA technology."
The arrival of two coronavirus vaccines in December allowed the world to breathe a small sigh of relief. But emerging variants of the virus — versions of SARS-COV-2 with slight genetic differences — are unwanted variables in an already precarious time. At least three are confirmed to be circulating, stemming from the United Kingdom, South Africa, and Brazil. An unpublished study also suggests a variant has emerged in California.
There’s a chance the virus may evolve to evade the vaccines we have now, but that’s far from confirmed. There’s good news: Even if it does, scientists say we can tweak our existing vaccines faster than you might think.
In late January, Moderna Inc. and Pfizer released data suggesting those vaccines seem to work just as well against B.1.1.7, the variant first found in the UK (these findings both come from preprint papers that have yet to be peer-reviewed). Meanwhile, on Friday the vaccine development company Novavax announced in a press release its unapproved vaccine is nearly 90 percent effective in treating B.1.1.7.
Data on B.1.351, the variant linked to South Africa, is more worrisome. Data on the other variants, meanwhile, is lacking.
Does the Covid-19 vaccine work against variants?
Moderna’s study on eight people suggests antibodies produced by its vaccine were six-times less effective against the South African variant, but the vaccine is still expected to provide protection. This week, Pfizer also released the result of a study (another pre-print) on blood taken from 20 people who got the vaccine. Antibodies were slightly less effective when faced with a virus engineered to have some mutations (not all) found on the South African variant. Pfizer, in turn, suggested that the vaccine should still be effective against the new variant and that there was no need for a new vaccine to be developed. A 4,400-volunteer study in South Africa on the Novavax vaccine found it was just 49 percent effective. Ninety percent of the Covid-19 cases examined were attributed to the variant.
While mixed, these results have sounded an alarm. Moderna and Pfizer have signaled they are monitoring the situation and prepared to develop “tweaked” vaccines to specifically address B.1.351 and others that could arise in the future.
Fortunately, this should be easy to do, explains Norbert Pardi, an assistant research professor at The University of Pennsylvania, who studies mRNA-based medicine.
“I think this is one of the biggest advantages of the messenger RNA technology, besides safety and efficacy,” Pardi tells Inverse. “It's very flexible.”
Why it’s easy to tweak vaccines – To adapt an mRNA vaccine to a new variant, scientists could focus on just one piece of it: the genetic material contained inside the vaccine. This material codes for the coronavirus’ spike protein.
"Once the sequence of a new virus variant is known, it takes less than an hour to design a vaccine... "
Variants contain mutations in their genetic code that slightly change the sequence of the virus, including that of the spike protein. Scientists identify what those changes are by analyzing the genetic sequence of the variant. Then, they can manufacture a new piece of RNA that reflects those changes, explains Emily Voigt, the mRNA vaccine team manager at The Infectious Disease Research Institute, a non-profit biotech organization.
“Once the sequence of a new virus variant is known, it takes less than an hour to design a vaccine, specifically for the new variant,” Voigt tells Inverse.
From there, it might take scientists a few weeks to create the physical mRNA that goes into the vaccine. Then they’d scale up production of the vaccine and get it ready to be used in people. From start to finish, she estimates the process could be completed in “one or two months.”
That timeline fits with what drugmakers have predicted. Pfizer has indicated a vaccine could be made in about six weeks.
It’s still unclear how much human testing and oversight the FDA will require for “tweaked” vaccines. Neither Voigt nor Pardi predicts we would have to go through the full battery of testing we saw the first time we created these coronavirus vaccines, which took nine months from start to finish. Creating a vaccine in nine months was “ridiculously amazing” Voight says. “But we can't afford to wait even nine months every time a new strain comes around.”
Although the FDA has yet to give clear guidance on what it might expect, on Monday Janet Woodcock, the acting commissioner of the FDA, said on Twitter that the FDA was already considering “creating a pathway” for current vaccines to be updated to combat new variants. That pathway could allow mRNA vaccine makers to move fast, because they’ve already done a battery of safety testing of their vaccines, and will only be changing one feature of it.
“99 percent of what's in the vaccine itself is going to stay exactly the same,” Voigt points out.
Do vaccines already need to be changed? — Pardi says we can’t say for sure whether we will even need to tweak the vaccine. Even when faced with the South African variant, both vaccines are still expected to provide protection. The strength of the antibodies produced by both vaccines, even when faced with the variant linked to South Africa, should be enough to provide some protection — perhaps enough to make “tweaking” the vaccine unnecessary.
Antibody responses also don’t tell the whole story. These new analyses don’t reveal how the other facets of the immune system, like B-cells and T-cells, react when faced with the new variants. These cells can help produce antibodies, and even kill cells infected with the virus. To really know if the vaccines we have work, other measures of immunity need to be evaluated.
“I certainly hope that the current vaccines will provide a sufficient level of protection against new mutants including the South African variant,” Pardi says.
“But of course at this point. No one really knows what's going to happen."
It may be revealed protection remains strong enough where we don’t need to deploy a tweaked vaccine. Tal Zaks, Moderna’s chief medical officer said he thinks of developing tweaked vaccines as “an insurance policy.”
“Once there are reports like that coming out in the scientific community, that would be time for vaccine manufacturers to be jumping on it, and making vaccine candidates to these new strains,” Voigt says.
If we end up needing a new vaccine, making one shouldn't pose a huge scientific problem (rolling it out is another story). We might even start making them, as Zaks has suggested, as a backup plan.
Pardi says, at this point, there’s no evidence to suggest that people who have already been vaccinated would need to get another vaccine, but this could change as more variants emerge and we learn more. “We need more data to have the final conclusions,” he cautions.