What Happened to Variant-Specific COVID Vaccines?

With the FDA poised to weigh in on the data supporting boosters for COVID-19 vaccines — for the Pfizer-BioNTech shot (Comirnaty), at least — questions have been raised as to whether there’s still a need for variant-specific vaccines.

Earlier this year, some vaccine makers announced that they were developing variant-specific or multivalent vaccines. But as current versions of vaccines seem to provide lasting protection against severe illness, it’s not clear whether the other versions still have a role to play.

“Unless there is clear evidence of loss of protection, updating the vaccines every time a new variant takes over the population might not be the best strategy,” Ramon Lorenzo Redondo, PhD, a molecular virologist at Northwestern University in Chicago, told Bloomberg.

Pfizer and Moderna have made their cases that a third dose of their original vaccines directed at the “wild-type” strain bolsters antibody levels and protection against infection and severe disease.

Still, both companies, as well as other vaccine makers, have tailored vaccines under investigation, particularly for the Beta variant, which has been known for its ability to evade immunity — although it hasn’t established itself like Delta has.

In some cases, the status of these trials is unclear. Following is a summary of variant-specific or multivalent vaccines in the works.

Pfizer-BioNTech

Pfizer has Beta- and Delta-specific vaccines in development. The Delta-specific trial was supposed to start in August, but it’s not clear whether it has commenced.

A Pfizer spokesperson referred a question about its initiation to BioNTech, which is leading that program. As of press time, BioNTech did not respond to a press query.

In a statement, Pfizer emphasized that the companies are “confident in the protection and safety of the two-dose BNT162b2 COVID-19 vaccine. The vaccine continues to be highly efficacious in preventing COVID-19, including variants and to date, no variant, including Delta, appears to have escaped the protection of the vaccine.”

The company said it enacted booster studies to “ensure that our vaccine continues to offer the highest degree of protection possible,” following a waning in protection against infection.

“Phase III data show a booster dose of the current vaccine induces significantly higher SARS-CoV-2 neutralizing antibody titers to the wild-type strain compared to the levels observed after the two-dose primary series. Phase I data showed a similar pattern of booster responses against the wild-type, Beta, Lambda, and Delta variants,” the company noted.

Moderna

According to a press release about its 2021 R&D Day, Moderna has four vaccine candidates in development against variants: one against Beta, one against Delta, a multivalent vaccine targeting Beta and the wild-type strain, and a multivalent vaccine against Beta and Delta.

The company did not provide an update on the status of these trials in that release, and it didn’t return a request for comment.

This week, Moderna issued another press release stating that its original vaccine holds up well against Delta, citing real-world effectiveness data through June 30 when Delta was emerging, and CDC data through August showing high effectiveness against emergency visits and hospitalizations.

The company also stated that it believes data support a booster dose (50 mcg, or half the original dose), and submitted those data to FDA at the beginning of September.

Johnson & Johnson/Janssen

In July, Johnson & Johnson announced that a single dose of its original vaccine conferred strong protection against Delta and other variants, based on an assessment of blood samples from eight participants in the phase III ENSEMBLE trial, which showed good neutralizing antibody response.

The company did not return a request for comment as to whether it had COVID variant-specific vaccines in development.

AstraZeneca

The company announced in late June that it started enrolling the first patients in a phase II/III clinical trial for a version of its vaccine tailored to the Beta variant.

“Testing booster doses of existing vaccines and new variant vaccines is important to ensure we are best prepared to stay ahead of the coronavirus pandemic, should their use be needed,” said Andrew Pollard, PhD, of the Oxford Vaccine Group at the University of Oxford, in a statement.

AstraZeneca has not returned a request for comment as of press time.

Novavax

While many are still wondering about the status of Novavax’s initial COVID vaccine, the company announced in June that it had trialed a Beta-specific vaccine in preclinical models.

It’s not clear if that program has progressed. Novavax did not return a request for comment.