In what should be reassuring news for health systems the world over,  preliminary lab results suggest that Moderna’s authorised COVID booster dose of 50 µg offers 37-fold more protection against Omicron than the first two vaccine jabs after 29 days.

And a 100 µg booster -comparable to the dose received in the first two shots – offered even more protection – boosting antibody levels 83-fold – and to comparable levels seen against the Delta variant for the existing approved booster jab.

The encouraging results for the Moderna vaccine, reported to investors on Monday, follow on a similar report from Pfizer earlier this month on laboratory test results from its vaccine booster.

It means that existing the vaccine formulation will be sufficient, for the time being, to combat the new variant, allowing production to remain focused in the near-term on rolling out more doses of the existing vaccine.

“The dramatic increase in COVID-19 cases from the Omicron variant is concerning to all. However, these data showing that the currently authorized Moderna COVID-19 booster can boost neutralizing antibody levels 37-fold higher than pre-boost levels are reassuring,” said Stéphane Bancel, Chief Executive Officer of Moderna, in a statement.

“Based on the strength of neutralizing titers generated by mRNA-1273, the rapid pace of Omicron expansion, and the increased complexity of deploying a new vaccine, the Company will focus its near-term efforts to address Omicron on the mRNA-1273 booster,” the Boston-based company said in a statement. “The Company will continue to assess the breadth and durability of neutralizing antibodies from the multivalent booster candidates in the months ahead.”

Positive bellweather 

While the Moderna data has not yet been peer-reviewed, and is yet to be followed by data on the effectiveness of other COVID vaccine boosters against Omicron, it’s one more positive bellweather.

Some analysts had warned last week that rebooting global production lines for new vaccine formulations to meet Omicron head-on would be far more disruptive of global vaccine supplies for early 2022 than booster campaigns as such.

If existing vaccine production can continue uninterrupted – rather than slowing down and rebooting for a new formulation  – that will be good news for health authorities in countries busy rolling out booster doses – as well as those still trying to get more people vaccinated with their first and second dose.

In the case of the Moderna jab, the laboratory blood tests compared results from individuals boosted with one of two possible booster doses of the existing mRNA-1273 vaccine formulation – the already approved 50 μg dose and the 100 μg dose currently in Phase 2/3 trials. It also looked at two “multivalent” vaccine candidates (mRNA-1273.211 and mRNA-1273.213) designed to target previously identified variants of concern (Alpha, Beta and Delta) – but not specifically Omicron.

Neutralizing antibodies against Omicron were assessed in assays of blood samples from the recipients before and at 29 days after the booster dose. The research was conducted at laboratories of the National Institute of Allergy and Infectious Diseases’ (NIAID) Vaccine Research Center at Duke University Medical Center. A preprint submission is being prepared based on the data.

Booster doses yielded robust antibody response against Omicron – although still less than for Delta variant

All groups had low neutralizing antibody levels in the Omicron PsVNT assay prior to boosting. At day 29 post boost, the authorized 50 μg booster of mRNA-1273 increased neutralizing geometric mean titers (GMT) against Omicron to 850, which is approximately 37-fold higher than pre-boost levels.

At day 29 post boost, the 100 μg dose booster of mRNA-1273 increased neutralizing GMT to 2228, which is approximately 83-fold higher than pre-boost levels. Strikingly, the multivalent candidates boosted Omicron-specific neutralizing antibody levels to similarly high – but not higher levels than the original vaccine formulations now in use today.

On the down side, the 50 μg booster dose had 2.9 fold lower tiers of the neutralizing antibodies for Omicron, than in the case of the Delta variant.  However, the 100 μg booster dose generated neutralizing titers against Omicron at levels almost comparable to those generated by the approved, 50 μg dose against the Delta variant (2228 versus 2423).

Phase 2/3 study data of the higher booster dose of the existing formulation (mRNA-1273) among some 305 trial participants showed that it was generally safe and well-tolerated with only slightly higher adverse events.

While the results have net yet been peer-reviewed, Moderna said it would be posting a pre-print version of the study results shortly.

Despite the generally positive showing of the existing vaccine formulation, Moderna said it would continue R&D on yet a third, Omicron specific, variant vaccine (mRNA-1273.529), saying:

“Moderna’s first line of defense against Omicron will be a booster dose of mRNA-1273. Given the long-term threat demonstrated by Omicron’s immune escape, Moderna will also continue to develop an Omicron-specific variant vaccine (mRNA-1273.529) that it expects to advance into clinical trials in early 2022 and will evaluate including Omicron in its multivalent booster program.”

Image Credits: Flickr – Official US Navy.