The phrase "are nevertheless essential" is correct and usable in written English.
It can be used to emphasize that something remains important despite other factors or circumstances.
Example: "Although the project faced numerous challenges, the contributions of each team member are nevertheless essential to its success."
Alternatives: "are still crucial" or "remain vital".
But people from out of town are nevertheless essential.
Importantly, these proteins are not themselves mutated, but are nevertheless essential for maintaining cells in their cancer-related state.
Under attack, they have occasionally been provoked into responding that, whatever else might be said, their activities are nevertheless essential to supporting creativity, innovation, culture, development and so on.
All properties mentioned so far only support rough energy assessments, which are nevertheless essential for city-wide bottom-up energy related investigations.
For decades he studied these meiofauna, marine, microscopic "mud dragons" that live not among but between grains of sediment, that are smaller than a period on this page yet are nevertheless essential to marine food chains.
GTP hydrolysis and dynamic turnover are nevertheless essential for spatial regulation of Z-rings by accessory proteins that also mediate remodeling of FtsZ filaments into highly curved bundles and vortices [25, 26].
Not exactly bedtime reading, Deák's study is nevertheless essential for anyone wishing to understand the most important institution in the Dual Monarchy, the multi-ethnic Common Army.
The report says: "Despite the considerable public interest in this case, it is nevertheless essential that we do not comment on the allegation that MI5 had been trying to recruit Adebolajo as an agent.
It is nevertheless essential not to destroy possibility of better atmosphere at outset, and I trust that more care than ever will be taken on Polish side to avoid provocation in any sphere and to restrain press.
William Locke, reader in higher education studies at University College London's Institute of Education, says it is nevertheless essential that any attempt to measure learning gain should record value-added or "distance travelled rather than simply what students come out with in terms of degree qualifications or jobs".
There is nothing in the speech we have not heard, nor is there any sense that Obama has grown in the job, is ready to tell his own party (let alone the public, as he claims he has done) hard truths or do what may be unpopular but is nevertheless essential.
