Zika Vaccine Study Presents Very Positive Results

Moderna Zika vaccine mRNA1893 low dose levels found very effective
mosquito biting an arm
(Zika News)

A Massachusetts based biotechnology company announced new positive interim Phase 1 data from its Zika vaccine candidate, mRNA-1893. 

Moderna, Inc.’s first interim analysis of the mRNA-1893 study published on April 14, 2020, shows that 10 µg and 30 µg dose levels seroconverted 94% and 100% of seronegative participants, respectively.

And, mRNA-1893 vaccine effectively boosted seropositive participants at both dose levels and was found to be generally well-tolerated.

Following a 2-dose vaccination schedule of mRNA-1893 given 28 days apart, the 10 µg and 30 µg dose levels were both generally well-tolerated, and there were no vaccine-related serious adverse events (SAEs) or adverse events of special interest (AESI). 

The most frequent solicited adverse reaction was local pain at the injection site. 

The safety profile did not appear affected by the second vaccination nor a flavivirus-positive baseline serostatus.

The analysis also showed that the 10 µg and 30 µg dose levels induced a neutralizing antibody response in both flavivirus infection-naïve (seronegative) participants and in participants with pre-existing flavivirus antibodies (seropositive), as shown by geometric mean titers and seroconversion rates. 

Notably, a single vaccination of the 30 µg dose level was sufficient to convert baseline flavivirus seronegative participants. 

However, there was a clear benefit of a two-dose series given 28 days apart.

In the flavivirus-seronegative group:

  • Seroconversion rates after the second vaccination reached 94.4% in the 10 µg dose level and 100% in the 30 µg dose level, based on the PRNT50. MN data were consistent with PRNT50 data.

In the flavivirus-seropositive group:

  • The percentage of participants achieving a 4-fold boost in pre-existing PRNT50 titers after the second vaccination reached 50% in the 10 µg dose level and 75% in the 30 µg dose level, based on the PRNT50. MN data were consistent with PRNT50 data.

“I am encouraged by these interim Phase 1 data showing the ability of mRNA-1893 to elicit a strong neutralizing antibody response,” said Tal Zaks, M.D., Ph.D., Chief Medical Officer at Moderna, in a press release. 

“Our Zika program, along with our continued work on a vaccine candidate against the novel coronavirus, underscores our commitment to improving global public health through developing mRNA vaccines to prevent the spread of infectious diseases.”

This project has been funded in whole or in part with Federal funds from the Department of Health and Human Services; Office of the Assistant Secretary for Preparedness and Response; Biomedical Advanced Research and Development Authority.

It was granted Fast Track designation by the U.S. Food and Drug Administration (FDA) in August 2019. Moderna owns worldwide commercial rights to mRNA-1893.

Moderna is advancing messenger RNA (mRNA) science to create a new class of transformative medicines for patients.

Zika vaccine news published by Zika News.