The phrase "a less efficacious" is correct and usable in written English.
It can be used when comparing the effectiveness of two or more things, indicating that one is not as effective as the other.
Example: "The new treatment proved to be a less efficacious option compared to the standard therapy."
Alternatives: "a less effective" or "a more ineffective".
A parallel 2-stage design was employed so that a less efficacious arm could be terminated early.
Note that this average overall virologic suppression corresponds to that of a heterogeneous cohort; there are some members who are non-adherent, some who elect to change to a less efficacious non-HAART regimen, and some who discontinue HAART.
However, blotted EE-treated uteri were larger, consistent with past reports that TAM induces a less efficacious uterotrophic effect [ 20].
We investigate this issue in terms of achieving twice the coverage with a less efficacious 1-dose vaccine but with a shorter delay to full seroconversion.
A less efficacious product may have the greatest public health benefits, as the relative failure of condoms and VCT have shown [ 4, 6, 7].
Saphenous vein responses to insulin were similar in magnitude to those observed with PDGF-BB whereas insulin was a less efficacious mitogen than PDGF-BB in internal mammary cultures.
Consistent with its putative actions, harmine produced a similar, though less efficacious, inhibition of C-shapes elicited by the substituted amphetamines methamphetamine and mephedrone (4-methylmethcathinone) but was much less effective against nicotine.
In the study by Bianco et al. [46] dedicated to headache patient management by general practitioners in Italy, less than half (46.7%) of the GPs modified the treatment when new scientific evidence indicated that its use for a patient was less efficacious that the new one.
In this model, the triple combination, containing primaquine (0.25 mg/kg), was marginally but significantly (P = 0.0014) less efficacious than A-L alone (inhibition in oocyst intensity of 71%[955% CI of 43 to 86] compared to 94%[955% CI of 88 to 97], mean oocyst intensity = 16.6 [SEM = 3.2], oocyst prevalence = 69.5%).
We assumed that all vaccine was delivered and administered at once, and more realistic rollouts would result in a slower and possibly less efficacious global mass vaccination campaign.
In addition, as emphasised by Noon et al (2013), our findings confirm that, when BCG therapy is indicated, it should also be performed in the elderly, because age does not seem to be a criterion indicating other less efficacious therapies.
