The first booster of the COVID combination has now entered Australia’s vaccine program, with Moderna’s Omicron vaccine officially entering the rollout from today, according to the Department of Health and Human Services.
The Australian Technical Advisory Group on Immunization (ATAGI) recommended last month that the vaccine, which consists of vaccines against the original SARS-CoV-2 virus and the BA.1 Omicron subvariant, be given as a booster to adults.
Combined boosters have also been implemented elsewhere, including the UK, Switzerland, Canada, the EU and the US, with the US releasing a booster tailored to BA.4 and BA.5 instead of BA.1.
So who can get the new booster and how much protection does it offer?
Who can get it and how?
Moderna’s new booster, called Spikevax Bivalent Original/Omicron, or mRNA-1273,214, has been approved for use in people 18 and older.
ATAGI recommends that it be given at least three months after the most recent dose of the COVID-19 vaccine or COVID infection, but you do not need to give it if you are already up to date with your boosters.
The combination booster can be given at the same time as the non-COVID vaccines.
It is not yet approved for children under 18 years of age, nor should it be used as a “primary dose” vaccine (one of the first two doses in most people or the first three doses in severely immunocompromised people ).
To find out where the new boosters are available, you can use the health department’s clinic locator.
How is the new booster different from the original Moderna COVID vaccine?
Like the original Moderna COVID prime and booster shots, the booster combination is an mRNA vaccine.
It contains genetic blueprints that, when injected into our muscle, cause our body to build replicas of the SARS-CoV-2 spike protein.
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These alert our immune system, which produces antibodies that form an immune “memory” of the spike. They can then neutralize the actual virus, should the immune system find it along the way.
But where the first Moderna vaccine contained only spike protein blueprints for the original SARS-CoV-2 virus, the new combination booster also includes blueprints for the Omicron BA.1 subvariant spike, which was widely circulated when it was developed the vaccine at the beginning of the year.
BA.1, and its set of Omicron siblings, have at least 30 mutations in their spike protein compared to the original virus, giving it a slightly different shape.
The original COVID vaccines are less effective at neutralizing infections caused by these new subvariants because the antibodies they generated are less likely to recognize the Omicron spike proteins (but some still can).
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Why include mRNA for the original virus?
Given that almost none of the ancestral SARS-CoV-2 viruses are now circulating and Omicron has dominated infections by 2022, why include mRNA against the original virus?
When faced with less mutated variants such as Delta, the original mRNA vaccines provided strong protection against infection, hospitalization and death (although this declined over time).
And we don’t know what the virus will do next.
It will almost certainly become another variant, but older ones could return, so having broader protection is one way to prevent potential future infections.
How well does it work?
Almost everything we know about Moderna’s combo boosters comes from Moderna’s own testing.
Preliminary results showed what ATAGI called “a small incremental benefit” in an immune response against Omicron’s BA.1, BA.4 and BA.5 subvariants.
In a study published in the New England Journal of Medicine, about 800 triple-vaccinated people received either a fourth dose of the original Moderna vaccine or the new combined booster.
Both cohorts made antibodies that could neutralize the ancestral virus and BA.1 (they are similar enough that the original vaccine generates some antibodies capable of latching onto BA.1), but those with the combined boost ended up with an average of 1.75 times. the BA.1 antibody response after 28 days compared to the original vaccine group.
The combination vaccine also gave recipients higher levels of antibodies against the BA.4 and BA.5 variants, especially if they had previously been infected with COVID.
Moderna’s chief medical officer, Paul Burton, told the ABC in June that these antibody levels are “guaranteed to correlate with clinical protection against infection and serious disease.”
But it’s not yet known exactly how these antibody levels translate into prevention of infection, hospitalization and death in the real world, nor do we know how long the antibodies last.
There were some breakthrough infections in Moderna’s study.
The researchers wrote, “In an exploratory analysis, SARS-CoV-2 infection occurred in 11 participants after the [combination] reinforcement and in nine participants after the [original] amplifier”.
Of these, six and seven, respectively, were asymptomatic infections.
It’s also important to note that we already know that Moderna’s original vaccine provides protection against serious disease against Omicron’s subvariants, and ATAGI recommends that “people who need to receive a dose of COVID-19 book an appointment, using any vaccine they have at their disposal”.
How safe is the new booster?
Moderna’s combined booster has a similar safety profile to the original.
In the trials, the most common local adverse reactions after combination vaccination as a fourth dose of COVID vaccine, or second booster, were injection site pain (77%), fatigue (55%), sore none (44%). and muscle pains (40%).
Moderna’s combination booster trial is ongoing and, in a press release, the TGA confirmed that the pharmaceutical giant must provide information on the long-term results of these studies, including safety assessments, as well as continued follow-up after vaccine launch.
Like previous COVID vaccines, the combination boosters will be tested in batches before being distributed and administered to participating pharmacies and medical clinics as part of the existing rollout.
What other variant-specific vaccines are coming down the line?
Moderna’s combo shot might be the first to be used in Australia, but it won’t be the last.
Pfizer and Novavax are testing vaccines that aim to protect against more than one variant.
Research is also underway on scaled-down versions of current COVID vaccines, which are designed to try to generate a higher proportion of neutralizing antibodies, as well as vaccines that target parts of the virus that don’t mutate as quickly as the protein spike
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