In this study, the diagnosis of influenza-like illness trends with both influenza (which was decreasing up until March) and COVID-19 (which began sharply increasing in March). In 3 of the 4 regions of New York State (not including NYC), the diagnoses of ILI increased ahead of the emergence of COVID-19.
- Influenza-like illness (ILI) is defined as fever of 100°F or greater with cough and/or sore throat in the absence of another known cause
- Used two sources for data:
- Outpatient Influenza-like Illness Surveillance Network (ILINet)- For ILI prevalence
- NY State Department of Health database- influenza types A-B and SARS-CoV-2 tests from state-wide laboratories are reported to this database
- Until the emergence of COVID-19 in early March, ILI and laboratory-confirmed influenza tracked closely together, with both declining.
- Afterwards, in the Metropolitan region of NYS region, with the highest rates of confirmed COVID-19, ILI increased most sharply.
- In the other three regions, ILI increased ahead of the emergence of COVID-19. This might signal early COVID-19 activity without diagnosis in those regions or increased concern over COVID-19 and care-seeking among people with mild ILI