British scientists are set to begin trials to assess the
safety and effectiveness of two experimental coronavirus vaccines when inhaled.
Researchers at the Imperial College London and Oxford
University would test the vaccines being developed by both the institutions by
delivering them directly to the respiratory tract of human volunteers by
inhalation through the mouth rather than being injected.
“We’ve evidence that delivering influenza vaccines via a
nasal spray can protect people against flu as well as help to reduce the
disease transmission. We’re keen to explore if this may also be the case for
SARS-CoV-2 and whether delivering Covid-19 vaccines to the respiratory tract is
safe and produces an effective immune response,” Dr Chris Chiu, Department of
Infectious Disease, Imperial, who will lead the project, said in a statement.
A total of 30 people are expected to be recruited to the
trials. For each vaccine, researchers will assess three dose levels (low,
medium and high dose) with three volunteers per group (18 in total), followed
by an additional six in each group at the best dose (12 total).
In addition to blood and nasal sample analyses, volunteers
will undergo bronchoscopy to obtain samples from deeper within the lungs and
monitor the effects in the lower respiratory tract. They will receive
aerosolised vaccines through a nebulizer, which will deliver the vaccine as
airborne droplets through a mouthpiece. With direct vaccine administration to
the respiratory tract, based on previous studies, lower doses may be required
than by intramuscular injections to induce protective responses.
In addition to blood being analysed for the presence of
neutralising antibodies (Immunoglobulin G, or IgG) and T cells, which fight the
virus and protect against re-infection, the team will analyse nasal samples for
the presence of specialised antibodies found in the nose and throat, called
IgA, which would indicate a more specialised and localised immune response to
The Imperial vaccine uses synthetic strands of genetic code
based on the virus. Once injected into the muscle, the body's own cells are
instructed to make copies of a spiky protein on the coronavirus. That is
expected to trigger in turn an immune response so the body can fight off any
future Covid-19 infection.
The Oxford vaccine though uses a harmless virus — a chimpanzee cold virus, to carry the coronavirus' spike protein into the body, which should trigger an immune response. Last week, Oxford temporarily paused its large-scale vaccination tests after one participant reported severe neurological symptoms. It was restarted on Sunday last.