Table 2.

Vaccination strategies and resulting NAb response in clinical trials.

Vaccination Approach	Rationale	Result	Reference
Subunit Protein	Subunit based immunizations have been successfully used to raise antibody responses to a number of pathogens	Narrow NAb responses with no protective efficacy	[34, 35]
Viral Vectors	Raise a balanced T and B cell response	Narrow, low titer NAb responses elicited, when observed at all	[79, 80]
DNA Vaccines	Raise a balanced T and B cell response	No NAb responses elicited	[85–87]
Viral Vector + Protein	Viruses alone elicited only low quality antibody responses that may be boosted with a recombinant protein	Increase in NAb titers with administration of protein boost	[80]
DNA + Viral Vectors	Adenoviruses may be capable of boosting low titer immune responses resulting from DNA priming	Increased potency but still limited breadth of NAb	[90]
DNA + Protein	DNA immunizations can successfully prime a humoral response which can be augmented by boosting with a subunit protein	Low titer, but broad NAb responses against a wide range of primary isolates	[120]