Image copyright City of London Image caption A 1977 study suggested that a common type of vaccine was effective against type Omicron virus
A type of vaccine against an immune deficiency disease remains largely unknown more than 50 years after its introduction, experts say.
Omicron has been shown to prevent infections by a version of the virus that is normally fatal to children, but the antibody response of adults is poor.
There is no cure and treatment for the illness is usually limited to supportive care.
Experts from the UK, US and Canada are attending a conference to discuss the subject.
The virus, which produces liver failure, is a tropical infection of the respiratory tract. Omicron is one of the most common causes of congenital hepatitis, or neonatal tetanus.
Symptoms include high fever, severe fatigue, nausea, vomiting, poor appetite, liver problems and ataxia. There are usually no signs of infection for months.
Prof Robert Tapper, from Newcastle University, said: “The condition often goes undiagnosed and many suffer from severe (even life-threatening) symptoms for months before being diagnosed.
“Fewer than a fifth of people infected with type Omicron ever develop a sign of the virus in the blood. Many are in desperate need of treatment.”
Men and women infected with the virus experience a high level of antibody production – however around one in five do not produce a sufficient level of the antibodies and therefore have no protection.
Scientists are now attempting to use UK government funding of an immunotherapy treatment for type Omicron – the JCAR015 vaccine – to find out what effects it has in adults who are still able to respond to existing treatments.
Just 16% of adults in the UK are now vaccinated against type Omicron, compared to 80% for type BHV and the same for type A.
In the UK the vaccine is only available in hospital settings, but the administration of a general dosage to healthy adults is currently available through a local GP surgery.
Prof Tapper added: “The next step is to find out if immunisation is as safe in the general population as in children.”