Resources must be invested in the simple diagnostic tests so that it can help in saving thousands of lives and end disease epidemics in the developing world, said scientists from the Imperial College London.
One of the studies found that wider use of a device called pulse oximeter to measure oxygen in the blood could prevent 148,000 pneumonia deaths in the under-fives in countries where the disease is most prominent. But the device is not routinely available in community settings.
The authors argued that if pulse oximetry was made available more widely in the community, it could allow children to be diagnosed quicker and sent to hospital for life-saving oxygen and antibiotics.
The researchers also call for investment in diagnostic tools to detect those that are infected but may not show any symptoms of disease.
For example, current diagnostic tests for malaria involve just a blood finger-prick. But they currently only identify around half of those that are infected.
A simple improvement in these tests to detect a 10-fold lower density of parasites in the blood could increase this to over 80 percent, researchers said.
"Increasing the sensitivity of these tests could improve the prospect of malaria elimination," said study's lead author Hannah Slater.
A third paper from Imperial authors calls for the use and further development of rapid diagnostic tests for Ebola.
Testing a patient for Ebola took between two days and a week in the recent outbreak. But in this time the patient had to remain in a "holding area" - where infected and uninfected patients stayed together until their results were confirmed. This increased their risk of contracting Ebola, as well as taking up limited bed capacity.
The authors calculated that if rapid tests had been available and used from the start of the recent outbreak, it could have reduced its scale by a third. The findings were published in the Journal Nature.