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Microbiology: Current Research
Volume 2
International Conference on
Emerging Diseases, Outbreaks & Case Studies
&
16 th Annual Meeting on March 28-29, 2018 | Orlando, USA Influenza
Introduction: Immune profile for influenza viruses is highly
changeable over time. Serological studies can assess the
prevalence of influenza, estimate the risk of infection,
highlight asymptomatic infection rate and can also provide
data on vaccine coverage. The aims of the study were to
evaluate pre-existing cross-protection against influenza A
(H3) drift viruses and to assess influenza immunity in the
Portuguese population.
Materials & Methods: We developed a cross-sectional
study based on a convenience sample of 626 sera collected
during June 2014, covering all age groups, both gender and
all administrative health regions of Portugal. Sera antibody
titers for seasonal and new A (H3) drift influenza virus
was evaluated by hemagglutination inhibition assay (HI).
Seroprevalence to each seasonal influenza vaccine strain
virus and to the new A (H3) drift circulating strain was
estimated by age group, gender and region and compared
with seasonal influenza-like illness (ILI) incidence rates
before and after the study period.
Results: Our findings suggest that Seroprevalence of
influenza A (H3) (39.9%; 95%CI: 36.2–43.8) and A (H1) pdm09
(29.7%; 95% CI: 26.3–33.4) antibodies were higher than for
influenza B, in line with high-ILI incidence rates for A (H3)
followed by A (H1) pdm09, during 2013/2014 season. Low
pre-existing cross protection against new A (H3) drift viruses
were observed in A (H3) seropositive individuals (46%). Both
against influenzaA (H1) pdm09 andA (H3) Seroprotectionwas
highest in younger than 14-years old. Protective antibodies
against influenza B were highest in those older than 65 years
old, especially for B/Yamagata lineage, 33.3% (95% CI: 25.7–
41.9). Women showed a high Seroprevalence to influenza,
although without statistical significance, when compared to
men. A significant decreasing trend in seroprotection from
north to south regions of Portugal mainland was observed.
Conclusions: Our results emphasize that low seroprotection
increases the risk of influenza infection in the following
winter season. Seroepidemiological studies can inform
policy makers on the need for vaccination and additional
preventive measures.
Speaker Biography
Raquel Guiomar is a Virologist at National Institute of Health, Portugal (Influenza and
other respiratory viruses)responsible for the National Laboratory of Reference for
Influenza Virus and Other Respiratory Viruses of the Ricardo Jorge Institute.
e:
Cross-protection to new drifted influenza A (H3) viruses and prevalence of protective antibodies to
seasonal influenza, between 2014 in Portugal
Raquel Guiomar, Susana Pereira da Silva, Patrícia Conde, Paula Cristóvão, Ana Carina Maia, Pedro Pechirra, Ana Paula Rodrigues and Baltazar Nunes
National Institute of Health Lisboa, Portugal