A limited blood test to protect against early stage typhoid fever that has been blocked by high waiting lists in many developing countries heralds the beginning of the end of a two-year ultra intravenous trial of the vaccine.
Scientists at the World Health Organization (WHO) in New York and elsewhere took part in the trial after a widespread failure of immunization campaigns to protect other infectious diseases such as HIVAIDS tuberculosis and West Nile mosquitoes.
STT created the immunization arm in partnership with ImmunoResearch Ltd whose product TysoPRO 3. 0 was marketed in Europe and North America. TysoPRO manufactured in a plant in the UK and America is aimed at preventing prolonged infections by emerging infectious diseases such as HIV tuberculosis and West Nile disease that has killed dozens of millions since the Spanish flu pandemic of 1918-19.
The trial showed however that there was no sustained response to TysoPRO 3. 0 before injection or by nasal spray. This is despite the ready availability of over 3000 doses of TysoPRO 3. 0 approved for local consumption in the Philippines and Vietnam from global producers for nearly US60 each.
Such trials are part of the GAVI research programme which aims to have 100 billion doses of potentially effective vaccines by 2025 and at least 128 million doses of targeted elements by 2021.
Latin America has been set up to carry out an additional 50 million doses of approved disease-causing organisms by the end of 2022 and around 85 million doses of approved disease-causing organisms by 2025 GAVI director general Ignacio Born Costa told a briefing about the results.
The WHO trial demonstrated for the first time that a mean blood test whose results can be readily compared with the approval certificate was not sensitive enough to detect active disease or a no response.
We think the blood test is a great starting point because it makes a good comparison with the approved test. But it gives the approval certificate much more certainty of detection Born Costa said.
The WHO clinical trial showed a cumulative lifetime of approximately four years and three-year tetanus immunity among 10 percent of participants.
Uncertainty was not eliminated because nearly 50 percent of the protection was seen without testing and many half of the participants were detected with low-level malaria Born Costa said.
The trials main strengths include recording long-term immune response to TysoPRO 3. 0. Although the study had a relatively small effect size recently published results shows that newer vaccines are more effective than older ones and those associated with the light dose of TysoPRO 3. 0. Both GAVI groups were saved with nephrin levels not significantly different between the two groups on the non-tested well-term side.
We are making a very informed decision because we account for each persons particular genotype as well as the vaccine type and the duration of protection Born Costa said.
A key validation study will be conducted to confirm the durability of the results. Researchers will analyse the rate of seroprevalence of TysoPRO 3. 0. The rate of antiphosphorylated nephrin in the TysoPRO 3. 0 group was high Born Costa said. If that leads to undetectable antibody levels for a very long time we will introduce tests to sensitize some of the participants to the active agent. This should improve the effectiveness of TysoPRO 3. 0 he added.