Incidence of Influenza Virus Pneumonia During the Time of Coronovirus-2019 Pandemic

Abstract

Since the beginning of coronarvirus-2019 pandemic, prevention has been the core measure to mitigate the spread of the virus. Prevention measures included universal masking, frequent hand sanitization, and social distancing are among the measures that proved to be effective. However, these measures are also known to be effective against transmission of influenza virus. We hypothesize that during the times of Covid-19 pandemic, the incidence of influenza pneumonias will also decrease. METHODS:We utilized the Jersey Shore University Medical Center Laboratory database to identify the number of influenza tests sent before and during the pandemic. We extracted the data over the last six months in 2019 to represent the pre-pandemic period and compared them to the data of the last six months in the year of 2020 to represent the during-pandemic period. In addition, we compared the rate of decrease in monthly incidences of Influenza cases between Feb-April 2020 in our hospital (when preventive measures were applied state wide in NJ) to Feb-April of 2017 in the Mid-Atalatnic District (obtained from the Healthcare Cost and Utilization Project National Inpatient Sample 2017) to better elicit the effect of preventive measures as opposed to the natural course.RESULTS: During the last six months of 2019, there was a total of 10,304 flu tests sent inpatient. Of them, 674 tests were positive (6.5%). In comparison, there was a total of 5,406 total tests of influenza A and B sent during the last six months of year 2020; among them, only 1 case was positive (0.02%). Relative risk was 0.003. By examining the Mid-atalantic district trend of monthly incidences of influenza, it appears that influenza cases in all hospitalizations decreased from 2.5% in Feburary 2017 to 1.2% in March 2017 to 0.7% in April 2017 (Monthly decrease of 40-50%); while the incidence in our hospital decreased from 9.6% in Feburary 2020 to 2.7% in March 2020 to 0.7% (Monthly decrease of 70-75%). CONCLUSIONS:The incidence of influenza virus pneumonia has decreased significantly during the time of Covid-19 pandemic, likely due to widely encouraged preventive measures.CLINICAL IMPLICATIONS: Masking, frequent hand sanitization and social distancing proved to be very effective in reducing the incidence of influenza pneumonia. Preventive measures may be adopted in patients with high risk of mortality from influenza pneumonia, even if Covid-19 pandemic resolves.

Trends in Hospitalization and Mortality for Influenza and Other Respiratory Viruses during the COVID-19 Pandemic in the United States

“…Our findings are consistent with the Influenza Hospitalization Surveillance Network from the US, which reported influenza-related hospitalizations as 0.8 per 100,000, the lowest since 2005 [ 12 ]. Alshami et al reported their institutional data from New York, describing a decline in influenza positivity from 6.5% to 0.02% during the last six months of 2020, which is in parallel with our findings [ 13 ]. A nationwide Canadian study by Groves et al reported data from a pediatric population that demonstrated a complete absence of influenza-related hospitalizations, intensive care unit admissions, or deaths [ 14 ].…”