Influenza Vaccination Strategies: Comparing Inactivated and Live Attenuated Influenza Vaccines

Abstract

Influenza is a major respiratory pathogen causing annual outbreaks and occasional pandemics. Influenza vaccination is the major method of prophylaxis. Currently annual influenza vaccination is recommended for groups at high risk of complications from influenza infection such as pregnant women, young children, people with underlying disease and the elderly, along with occupational groups such a healthcare workers and farm workers. There are two main types of vaccines available: the parenteral inactivated influenza vaccine and the intranasal live attenuated influenza vaccine. The inactivated vaccines are licensed from 6 months of age and have been used for more than 50 years with a good safety profile. Inactivated vaccines are standardized according to the presence of the viral major surface glycoprotein hemagglutinin and protection is mediated by the induction of vaccine strain specific antibody responses. In contrast, the live attenuated vaccines are licensed in Europe for children from 2–17 years of age and provide a multifaceted immune response with local and systemic antibody and T cell responses but with no clear correlate of protection. Here we discuss the immunological immune responses elicited by the two vaccines and discuss future work to better define correlates of protection.

Factors Associated with Lethal Outcome in Patients with Severe Form of Influenza

“…The answer probably lies in two important issues. The first one is the small group of patients and the second one arises from the existence of resistant forms of the virus [21,22].…”

Nasal-associated lymphoid tissues (NALTs) support the recall but not priming of influenza virus-specific cytotoxic T cells

“…Following inhalation of LAIV, the palatine tonsils, the NALT equivalent in humans, is the site where the humoral immune response is initiated (15). Although the vaccine is clearly able to elicit HA-specific neutralizing antibodies, it is still unclear whether protective influenza-specific T cells are generated in humans following LAIV vaccination (16,17). Here we showed that NALTs can only support memory T-cell expansion and not naïve T-cell priming following antigen delivery into the URT.…”

A critical role of T follicular helper cells in human mucosal anti-influenza response that can be enhanced by immunological adjuvant CpG-DNA

“…The relative predominance of IgG antibody production is concordant with the general predominance of IgG immunocytes in adenotonsillar tissue (Boyaka et al, 2000). A liveattenuated vaccine, which resembles more closely to a natural infection, is generally used without an adjuvant and activates a stronger innate and broader immune response than an inactivated vaccine (Siegrist, 2013;Sridhar et al, 2015). For an inactivated virus antigen, an adjuvant is usually needed and some adjuvants have been shown to greatly augment the immune response induced by inactivated influenza vaccines (Nicholson et al, 2001).…”