The phrase "previously effective" is grammatically correct and can be used in written English.
It is typically used to refer to something that was effective in the past, but may not be currently effective. Example: "The previously effective marketing strategy no longer seems to be resonating with our target audience."
Bacteria and other microbes that cause diseases in humans and animals are becoming increasingly resistant to previously effective drugs.
The global health crisis surrounding antibiotic resistance, which sees bacteria evolve until previously effective drugs no longer work, has leapt up the political agenda in recent months.
And if resistance spread from Asia to Africa, or emerges in Africa independently – as has been seen before with previously effective but now powerless antimalarials – "millions of lives will be at risk", they said in a report.
Since then, however, bacterial resistance to one or more antibiotics has increased to the point that previously effective antibiotics are no longer useful against certain types of bacteria.
And a serious problem is emerging: some are rebelling or asserting independence by skipping or stopping medication, which can make H.I.V. spiral out of control and become impervious to previously effective therapies.
Moreover, the assumption of previously effective medication could induce or worsen headache.
The emergence of new D. noxia insecticide resistance has not been reported, but the aphids Myzus persicae, Aphis gossypii, and Schizaphis graminum have each developed resistance to several previously-effective insecticides [ 87- 89].
The failure of chlorine has been documented (33 ), but use of post hand washing alcohol gel, previously found effective in terminating outbreaks (13, 34 ), was not effective in our experience.
To estimate the cost-effectiveness of a supported employment (SE) intervention that had been previously found effective in veterans with spinal cord injuries (SCIs).
But recent attempts at street demonstrations, which have previously been effective, were thwarted by a government show of force.
Other ED-based intervention programs, however, have previously proven effective.
