Association between Haemagglutination inhibiting antibodies and protection against clade 6B viruses in 2013 and 2015

Abstract

Background The epidemiology of the pandemic A(H1N1) virus has been changing as population immunity continues to co-evolve with the virus. The impact of genetic changes in the virus on human’s susceptibility is an outstanding important question in vaccine design. In a community-based study, we aim to 1) determine the genetic characteristics of 2009–2015 pandemic H1N1 viruses, 2) assess antibody response following natural infections and 3) assess the correlation of A/California/07/09 antibody titers to protection in the 2013 and 2015 epidemics. Methods In a household transmission study, serum specimens from 253 individuals in Managua, Nicaragua were analyzed. Combined nose and throat swabs were collected to detect RT-PCR confirmed influenza infection and virus sequencing. Hemagglutination inhibition assays were performed and the protective titer for circulating H1N1pdm was determined. Results Clade 6b pandemic H1N1 viruses predominated in Nicaragua during the 2013 and 2015 seasons. Our household transmission study detected a household secondary attack rate of 17% in 2013 and 33% in 2015. Infected individuals, including vaccinees, showed an apparent antibody response to A/California/07/09. Baseline titers of A/California/07/09 antibodies were found to associate with protection in both seasons. A titer of ≥1:40 correlated to a 44% protection in children, a 29% protection in adults 15–49 years old and a 51% protection in adults 50–85 years old. Conclusion In 2013 and 2015, antibody titers to A/California/07/09 associated with an infection risk reduction amongst exposed household contacts. This is consistent with a detectable vaccine effectiveness reported in a number of studies.. Genetic changes in clade 6b viruses might have led to a reduced immunity in some whereas others might have been less affected. The use of human serologic data is important in virus characterization and if performed in a timely manner, could assist in vaccine strain selection.

Novel correlates of protection against pandemic H1N1 influenza A virus infection

“…Details of the study design are published. 35,36 Participants were excluded from this analysis if sufficient blood samples were not available. The principles of the Declaration of Helsinki were strictly followed.…”

Nano-based approaches in the development of antiviral agents and vaccines

“…Antibody titers are closely correlated with vaccine effectiveness. Nanovaccines have been shown to induce high antibody titers [ [102] , [103] , [104] , [105] ], probably due to their superiority in target delivery and DC activation as well as the capacity to carry large amounts of antigens [ 106 ]. Nanovaccines can be constructed to carry large quantities of peptides or protein antigens; this provides a high concentration of antigens for efficient B cell receptor (BCR) signaling, consequently improving the B cell response and antibody production ( Fig.…”

Estimating and interpreting secondary attack risk: Binomial considered biased

“…The idea was originally developed by Charles V. Chapin in 1903 to study the transmission of diphtheria and scarlet fever, and it was extended to influenza, tuberculosis, and other infectious diseases by Wade Hampton Frost [8][9][10]. Household surveillance data from emerging infections is often used to estimate the SAR, including 1957 and 1968 pandemic influenza [11][12][13], meningococcal disease [2], pertussis [6], SARS coronavirus [14], seasonal influenza [15][16][17][18], rotavirus [19], 2009 pandemic influenza A (H1N1) [20][21][22][23][24][25][26], MERS coronavirus [27,28], Ebola virus disease [29][30][31], norovirus [32,33], hand-foot-and-mouth disease [34], cryptosporidium [35], measles [36], and COVID-19 [37,38].…”