Comparing the clinical severity of the first versus second wave of 2009 Influenza A (H1N1) in a New York City pediatric healthcare facility

Abstract

At our pediatric healthcare facility in New York City, fewer children were hospitalized with 2009 Influenza A (H1N1) during the second wave, but both waves had a similar spectrum of illness severity and low mortality rate.

Pediatric acute respiratory distress syndrome associated with human metapneumovirus and respiratory syncytial virus

“…The clinical course included the incidence of acute or acute‐on‐chronic respiratory failure, duration of oxygen therapy, and invasive mechanical ventilation, and use of high frequency oscillatory ventilation (HFOV) or extracorporeal membrane oxygenation (ECMO). Acute respiratory failure was defined as new treatment with mechanical ventilation (either invasive or noninvasive) . Acute‐on‐chronic respiratory failure was defined as the use of increased mechanical ventilation support (either invasive or noninvasive) compared to baseline mechanical ventilation support.…”

Impact of the 2009 Influenza A (H1N1) Pandemic on Healthcare Workers at a Tertiary Care Center in New York City

“…A decreased severity of illness during the second wave has previously been noted in the community setting as well as in our hospitalized pediatric population. 6,7 This may be a result of more timely access to antiviral therapy or the introduction of the H1N1 vaccine.…”

Epidemiology of SARS-CoV-2 during the first three waves in Scotland: a national record linkage study

“…Previous pandemic viruses have also typically presented in waves of infection; notably, the 1918 influenza pandemic occurred over three distinct waves, with the second and third waves proving most deadly 8. Studies investigating the epidemiology of more recent respiratory viruses, such as pandemic H1N1 and the 2002–2003 SARS outbreak, have demonstrated similar patterns 9 10. Although still early, currently published studies comparing the first few waves of COVID-19 have found an opposing pattern, with lower associated mortality or case fatality rates (CFRs) in subsequent waves compared with the first wave 11–14.…”

“… 8 Studies investigating the epidemiology of more recent respiratory viruses, such as pandemic H1N1 and the 2002–2003 SARS outbreak, have demonstrated similar patterns. 9 10 Although still early, currently published studies comparing the first few waves of COVID-19 have found an opposing pattern, with lower associated mortality or case fatality rates (CFRs) in subsequent waves compared with the first wave. 11–14 These observed decreases in mortality during later waves may be partly attributable to improved case detection, allowing for increased identification of mild or asymptomatic cases.…”