The phrase "are not fully effective" is correct and usable in written English.
It can be used to describe something that does not achieve its intended purpose or does not work as well as expected.
Example: "The current strategies we are using to increase sales are not fully effective, and we need to explore new approaches."
Alternatives: "are not entirely successful" or "are not completely efficient."
Many current policies aimed at reducing this pressure are not fully effective because the behavioural aspects of travellers are insufficiently recognised.
Several vaccines have been developed to inoculate Atlantic salmon from the virus, infectious salmon anemia, although researchers say they are not fully effective and are impractical to administer; it is not the case that such vaccines are nonexistent.
Moreover, it is well known that traffic counts are not fully effective in discerning between congested and uncongested traffic state of a link, because of non-monotone flow-density relationship.
Despite ongoing efforts to deal with convergence in standardization and coordination of standardization bodies by expertise centers and steering committees, the measures undertaken are not fully effective on the terminological level.
No studies have found that OR compounds used on surfaces are not fully effective against bacteria.
This indicates that Rap is still a hopeful drug even when conventional chemotherapeutic reagents are not fully effective.
The high percentage of single prescriptions of triptans may indicate that many migraineurs have relatively few attacks or that triptan therapy does not effectively control their migraine because it is not fully effective and/or has side effects.
Despite the use of a variety of medications, treatment of RA is not fully effective in most patients and side effects frequently limit their long-term use.
European Union policies for maintaining agricultural activity in marginal areas were not fully effective in reducing grasslands abandonment.
However, the administration of exogenous CNP is not fully effective, due to its rapid clearance in vivo.
