Excess cases of influenza and the coronavirus epidemic in Catalonia: a time-series analysis of primary-care electronic medical records covering over 6 million people.
BMJ Open
; 10(7): e039369, 2020 07 29.
Article
in English
| MEDLINE | ID: covidwho-690379
ABSTRACT
OBJECTIVES:
There is uncertainty about when the first cases of COVID-19 appeared in Spain. We aimed to determine whether influenza diagnoses masked early COVID-19 cases and estimate numbers of undetected COVID-19 cases.DESIGN:
Time-series study of influenza and COVID-19 cases, 2010-2020.SETTING:
Primary care, Catalonia, Spain.PARTICIPANTS:
People registered in primary-care practices, covering >6 million people and >85% of the population. MAIN OUTCOMEMEASURES:
Weekly new cases of influenza and COVID-19 clinically diagnosed in primary care. ANALYSES Daily counts of both cases were computed using the total cases recorded over the previous 7 days to avoid weekly effects. Epidemic curves were characterised for the 2010-2011 to 2019-2020 influenza seasons. Influenza seasons with a similar epidemic curve and peak case number as the 2019-2020 season were used to model expected case numbers with Auto Regressive Integrated Moving Average models, overall and stratified by age. Daily excess influenza cases were defined as the number of observed minus expected cases.RESULTS:
Four influenza season curves (2011-2012, 2012-2013, 2013-2014 and 2016-2017) were used to estimate the number of expected cases of influenza in 2019-2020. Between 4 February 2020 and 20 March 2020, 8017 (95% CI 1841 to 14 718) excess influenza cases were identified. This excess was highest in the 15-64 age group.CONCLUSIONS:
COVID-19 cases may have been present in the Catalan population when the first imported case was reported on 25 February 2020. COVID-19 carriers may have been misclassified as influenza diagnoses in primary care, boosting community transmission before public health measures were taken. The use of clinical codes could misrepresent the true occurrence of the disease. Serological or PCR testing should be used to confirm these findings. In future, this surveillance of excess influenza could help detect new outbreaks of COVID-19 or other influenza-like pathogens, to initiate early public health responses.Keywords
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
Pneumonia, Viral
/
Coronavirus Infections
/
Influenza, Human
/
Pandemics
Type of study:
Diagnostic study
/
Experimental Studies
/
Observational study
/
Prognostic study
Limits:
Adolescent
/
Adult
/
Female
/
Humans
/
Male
/
Middle aged
Country/Region as subject:
Europa
Language:
English
Journal:
BMJ Open
Year:
2020
Document Type:
Article
Affiliation country:
Bmjopen-2020-039369
Similar
MEDLINE
...
LILACS
LIS