Intranasal Recombinant, Live-Attenuated COVID-19 Vaccine Candidate Displays Promise

California-based Meissa Vaccines announced today positive preliminary data from the interim analysis of 49 patients in a Phase 1 clinical study of MV-014-212, the company's intranasal recombinant, live-attenuated COVID-19 vaccine candidate.

The data show that a single adjuvant-free dose of MV-014-212 stimulated a strong nasal IgA antibody response in seropositive and seronegative adults.

Doses ranged from 10^3 to 10^5 PFU, with the 10^5 PFU dose inducing nasal IgA antibody levels that resembled natural immunity to SARS-CoV-2. In addition, safety data at all dose levels indicate MV-014-212 is highly attenuated, with no infectious vaccine virus recovered from any participant and no serious adverse events reported to date.

The Phase 1 clinical study is still enrolling participants, and full results are expected to be presented in a scientific forum next year.

While circulating IgG antibodies are essential for preventing serious lung disease, nasal IgA antibodies are necessary for blocking infection and transmission of respiratory viruses.

Injectable vaccines typically induce only serum (IgG) antibodies that circulate in the blood, whereas intranasal vaccines also generate mucosal (IgA) antibodies in the nasal cavity.

"The preliminary clinical data indicate a single, adjuvant-free, needle-free dose of Meissa's COVID-19 intranasal vaccine can stimulate a nasal IgA antibody response similar to that seen after SARS-CoV-2 infection, with an important difference – safety," said Robert Walker, M.D., Chief Medical Officer of Meissa Vaccines, in a press release.

"The initial safety data from this trial combined with our preclinical COVID-19 data and clinical data from Meissa's RSV vaccine candidate, which was also built on the AttenuBlock platform, support continued clinical development of MV-014-212."

"We will continue to advance Meissa's COVID-19 intranasal vaccine in this Phase 1 clinical trial in adults."

"And, we plan to evaluate it as a booster to complement injectable vaccines and initiate a Phase 1 pediatric study next year."