Background: Before pandemic (H1N1) 2009, less than 10% of serum samples collected from
all age groups in the Lower Mainland of British Columbia, Canada, showed seroprotection …

BACKGROUND: The recent H1N1 pandemic virus that emerged in 2009 resulted in high
morbidity rates mainly in younger individuals, albeit with relatively low mortality. We …

To understand the epidemic resurgence of influenza due to the 2009 pandemic influenza A
(H1N1) strain (A [H1N1] pdm09) during the 2013–2014 influenza season, we compared age …

Background The extent to which influenza recurrence depends upon waning immunity from
prior infection is undefined. We used antibody titers of Ha-Nam cohort participants to …

The new influenza strain detected in humans in April 2009 has caused the first influenza
pandemic of the 21st century. A cross‐reactive antibody response, in which antibodies …

To study the serologic response to the new pandemic influenza A (H1N1) 2009 virus in
Hong Kong, the level of immunity was measured before and after the occurrence of the …

Age-specific seroprevalences for influenza virus make important contributions to estimating
the burden of infection and determining the vulnerable populations. It is especially difficult to …

Objective To determine the community seropositivity of pandemic (H1N1) 2009 influenza in
order to estimate immunity and the community attack rate. Methods Selected clusters of …

Background In order to detect levels of pre-existing cross-reactive antibodies in different age
groups and to measure age-specific infection rates of the influenza A (H1N1) 2009 …

Abstract 2009 H1N1 pandemic influenza (A (H1N1) pdm09) virus infected large numbers of
people worldwide. Recent studies suggest infection with A (H1N1) pdm09 virus elicited …