Mucosal vaccines go directly into the mucosal tissue where infection begins – for example, intranasally or via tablets. If they could induce strong enough mucosal immunity, such vaccines could reduce the risk of infection and transmission. That’s often called “sterilizing” immunity.
Development of these vaccines has just received a massive boost. A global consortium is being funded to develop and then run human challenge trials of intranasal or inhaled vaccines in a program called MusiCC. A human challenge trial – where participants are quarantined and deliberately infected in that controlled environment – could find out quickly and definitively establish whether or not particular vaccines can prevent infection and transmission. If very effective vaccines are tested in this program, it would vault them rapidly through development stages that could otherwise take years.
As well, the US Government’s Project NextGen is calling for interest in developing and/or supporting oral Covid vaccines. This pair of new initiatives kick off this month’s update.
There is also some news from clinical trials for 2 intranasal vaccines, as well as development news on 2 vaccines in the “variant-proof” category, and several preclinical studies.
New development initiatives for mucosal vaccines
In the last few weeks, 2 initiatives aiming to boost the development of mucosal vaccines have been announced – a global human challenge trial program to be led by Imperial College London for inhaled and intranasal vaccines, and a request from US Project NextGen for parties interested in developing or supporting oral Covid vaccines.
Human challenge program: Mucosal Immunity in human Coronavirus Challenge (MusiCC)
This is a new 5-year program led by Imperial College London to speed development and access to mucosal coronavirus vaccines by running placebo-controlled human challenge trials. That involves trying to infect volunteers under controlled conditions, which means trials that can establish whether infection is blocked can be completed quickly, with fewer volunteers than a standard trial.
MusiCC is supported with $57 million from the European Union and CEPI (Coalition for Epidemic Preparedness Innovations). A global consortium of more than a dozen teams and organizations specializing in human challenge studies will be involved. They are interested in inhaled and intranasal vaccines that could block transmission of betacoronaviruses (the virus group including Covid and MERS). The program “includes a commitment that any vaccines developed are made available first and at an affordable price to the most vulnerable populations.”
From the announcement: “Using harmonised standard operating procedures, the trials will take place across several sites in the UK, Europe, the United States and Singapore and will each involve a small group of young, healthy volunteers. In the challenge trial, volunteers will first receive either a dose of an investigational vaccine designed to provide mucosal coronavirus immunity or placebo before being intentionally exposed to a calibrated dose of SARS-CoV-2. A model using a seasonal coronavirus called OC43 is also being developed for similar use.”
The first step is deciding on which variant of SARS-CoV-2 will be used, and then developing a version that can be used in the trials. Imperial College London has done this before. Their team published the results of a Covid human challenge trial with 36 people to test the process. They were able to infect just over half the participants with a version of the original virus (wild type).
The UK government provided funding for that original program, which was announced in October 2020. The trial got the regulatory green light to start in February 2021, and the first participants had left quarantine by March. The government funding for the whole program of which that trial was part, was £33.6 million – in pounds sterling for comparison, this new program is £44 million.
We don’t know yet which vaccines might be involved. Other than Imperial College London, the only other organization named in CEPI’s announcement is University of Antwerp’s Vaccinopolis. A statement from Imperial College London mentions a London hub for trials, and studying the biology of respiratory infection with the National Centre for Infectious Diseases (NCID) in Singapore.
New preclinical results for mucosal vaccines
I’ve added 3 preclinical reports on results for mucosal vaccines to my collection since the last update:
Vaxart (USA): This is a viral vector vaccine, and a tablet form is one of the vaccines with Project NextGen funding for a phase 2 trial. The latest study tested 3 versions of the vaccine intranasally in primates, and included a group that received an injection and an intranasal dose. (Records in my collection for this vax here.)
Chengdu Kanghua Biological Products (China): This is also a viral vector vaccine. A study tested an intranasal version in mice, as standalone vaccine or booster.
Osaka University (Japan): This live attenuated virus vaccine was tested in intranasally in hamsters.
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