Now, new more transmissible variants that have emerged in different parts of the world have raised concerns about the protection they can offer — and vaccine makers are looking at updating their jabs.
“I think it’s clearly starting to look that … we’re going to have to, at some point, change the vaccines that we use to address the variants,” said Dr. Donald Vinh, an infectious disease specialist and a medical microbiologist at the McGill University Health Centre.
A new study published in the New England Journal of Medicine (NEJM) on Wednesday showed that the Moderna vaccine appears to be highly effective against the B.1.1.7 variant first identified in the United Kingdom, but showed a decrease in neutralizing antibodies against the B.1.351 variant found in South Africa.
The results of another study published in NEJM for Pfizer’s vaccine also suggested that the B.1.351 variant may reduce antibody protection by two-thirds, with researchers saying it is not clear if the shot will be effective against the mutation.
However, both companies have said that their mRNA-based vaccines are flexible and can be tweaked, if needed.
In a statement to Global News on Wednesday, Christina Antoniou, director of corporate affairs of Pfizer Canada, said if a new strain of the coronavirus were to emerge that is not covered well by the current vaccine, an updated jab could be administered as a booster.
“We are already laying the groundwork to respond quickly if a variant of SARS-CoV-2 shows evidence of escaping immunity by our vaccine,” she added.
U.S. pharmaceutical company Moderna said last month that while its two-dose regimen is expected to be protective against the variants, it will test an additional booster dose against emerging strains.
Meanwhile, AstraZeneca said last week that it was working to adapt its COVID-19 vaccine developed in partnership with Oxford University to combat new variants. The Anglo-Swedish company expects to have a new version ready for use by autumn this year.
Cases involving “variants of concern” that were first identified in the U.K., South Africa and Brazil, and which appear to be more contagious than the original SARS-CoV-2 virus, have been found in Canada.
“We don’t know whether these variants will continue to evolve where it gets to the point where the current vaccines that we have are no longer sufficiently effective,” said Dr. Scott Halperin, director of the Canadian Center for Vaccinology and an infectious disease specialist at Dalhousie University.
So how long does it take to update the vaccines?
Experts say that depends on the type of technology being used, but in any case, the process can be fairly quick and comparable in terms of the time required to make the tweaks.
For the messenger RNA (mRNA) platform, which is a relatively new way of making vaccines used by both Pfizer and Moderna, this would require changing the current molecules in the genetic sequence to target the variants of concern. This can take a few days to weeks, Vinh said.
Changes in the traditional viral vector approach being used by AstraZeneca and Johnson and Johnson or Novavax’s recombinant nanoparticle technology could be a “little more complicated,” according to Levon Abrahamyan, a virologist at the University of Montreal.
“But still, we are not talking about months or years,” he said about the time needed to make adjustments.
In theory, an updated vaccine should be able to target different variants with one shot.
“Certainly, there is a possibility that if there are multiple variants of concern circulating simultaneously, that one might want to have a vaccine that combined several of those variants,” Halperin said.
However, Vinh said trying to chase multiple variants in one go also raises some safety concerns.
He said changes in a vaccine to target several variants that may not be relevant could “potentially increase the risk,” with no additional benefit.
As is the case with the flu shot each season, Vinh said it is better to monitor the epidemiological data for which coronavirus variant was circulating and then make the changes accordingly.
So far, there has been no decision from the regulatory authorities on how to deal with vaccines for the new variants.
Substantial changes could mean new clinical trials will be required to establish the safety and efficacy of the new vaccines.
However, Halperin said it was “very unlikely” that the updated shots would have to go through all three phases of clinical trials, especially if the same antigen is being used. Antigen are molecules that stimulate an immune response.
But if “somebody is trying a whole different process, a whole different antigen, then it would have to go through clinical trials again,” he told Global News.
The European Union (EU) has established a bio-defence preparedness plan called the “HERA Incubator” to deal with the new variants.
Under this mechanism, the EU is aiming to support the speedy mass production of adapted COVID-19 vaccines.
Since it is not yet clear what the long-term immune response will be after vaccination, it still remains to be seen if an annual shot or regular booster jabs will be needed going forward.
“It’s likely that we’re going to need more vaccine shots for COVID in the future,” said Vinh.
“But is it going to be every year like the flu shot? … That’s a little bit hard to tell at this point.”