Influence of Prior Infection With COVID-19 on Occurrence of Influenza-like Illness or Acute Respiratory Infection (PICOV)

Influence of Prior Infection With COVID-19 on Occurrence of Influenza-like Illness or Acute Respiratory Infection

Influence of Prior Infection With COVID-19 on Occurrence of Influenza-like Illness or Acute Respiratory Infection (PICOV) A Multicentre Academic Prospective Cohort Study in Nursing Home During the Winter Season 2020-2021

Background: Each Belgian winter season is characterized by a wave of influenza like and respiratory symptoms. Especially, the elderly people are more vulnerable to be infected by influenza, but also RSV. The recent COVID-19 pandemic and eventually a next wave, will increase the prevalence of influenza like and respiratory symptoms. Method: A multicentre non-commercial cohort study will be conducted in nursing home staff and residents during the Winter season 2020-2021. Objectives: Primary objective is the difference in incidence of influenza like and respiratory symptoms between cases (cases have evidence of past infection with SARS-CoV-2, referred to as Covid +) and controls (controls have no evidence of previous infection and are referred to as Covid -). The primary outcome analysis as well as the secondary outcome analyses will use two strata: nursing home staff and nursing home residents. The secondary objectives are the difference in incidence of COVID-19, influenza, RSV infections confirmed by PCR between cases and controls, to define a correlate of protection in the covid + group against re-infection with SARS-CoV-2 based on the study of the pre-existing antibody profile (antigen specificity, antibody type and antibody level) at the time of re-exposure. A multiplex assay will be used to assess the antibody profile. Finally, to study the COVID-19 disease severity (7 point WHO ordinal scale, this includes a.o. hospitalisation, mechanical ventilation need and ICU admission, mortality) based on the presence/absence of pre-existing antibodies and the pre-existing antibody profile. For other respiratory infections we will study the need for hospitalization and mortality.

This study will assess the time to the occurrence of influenza-like illness (ILI) or acute respiratory infection (ARI) in subjects previously COVID+ compared to subjects known as COVID- (controls), more specifically subjects will belong to two subgroups: nursing home residents (65+) and nursing home staff (18-65y). COVID+ is defined as a past SARS-CoV-2 infection.

Correlation of the level of neutralization antibodies against influenza subtypes with protection against influenza reinfection

Inclusion Criteria: Being a staff member or resident from te participating nursing homes The subject should be aged 18 years or older, have a Belgian National Number and be insured by a Belgian sickness fund. All subjects that are cognitively capable to give consent themselves to participate in the study. Exclusion Criteria: Insufficient knowledge of the Dutch or French language. Residents with a previous diagnosis of dementia having a mini-mental state examination (MMSE) below 18/30. Participants which life-expectancy is less than the time of the study. Staff members not expected to continue working at the nursing home during the winter season. Participants for whom veins are not accessible for simple periphery blood puncture.