Clinical features and natural history of the first 2073 suspected COVID-19 cases in the Corona São Caetano primary care programme: a prospective cohort study

BMJ Open. 2021 Jan 12;11(1):e042745. doi: 10.1136/bmjopen-2020-042745.

Abstract

Background: Despite most cases not requiring hospital care, there are limited community-based clinical data on COVID-19.

Methods: The Corona São Caetano programme is a primary care initiative providing care to all residents with COVID-19 in São Caetano do Sul, Brazil. It was designed to capture standardised clinical data on community COVID-19 cases. After triage of potentially severe cases, consecutive patients presenting to a multimedia screening platform between 13 April and 13 May 2020 were tested at home with SARS-CoV-2 reverse transcriptase (RT) PCR; positive patients were followed up for 14 days with phone calls every 2 days. RT-PCR-negative patients were offered additional SARS-CoV-2 serology testing to establish their infection status. We describe the clinical, virological and natural history features of this prospective population-based cohort.

Findings: Of 2073 suspected COVID-19 cases, 1583 (76.4%) were tested by RT-PCR, of whom 444 (28.0%, 95% CI 25.9 to 30.3) were positive; 604/1136 (53%) RT-PCR-negative patients underwent serology, of whom 52 (8.6%) tested SARS-CoV-2 seropositive. The most common symptoms of confirmed COVID-19 were cough, fatigue, myalgia and headache; whereas self-reported fever (OR 3.0, 95% CI 2.4 to 3.9), anosmia (OR 3.3, 95% CI 2.6 to 4.4) and ageusia (OR 2.9, 95% CI 2.3 to 3.8) were most strongly associated with a positive COVID-19 diagnosis by RT-PCR or serology. RT-PCR cycle thresholds were lower in men, older patients, those with fever and arthralgia and closer to symptom onset. The rates of hospitalisation and death among 444 RT-PCR-positive cases were 6.7% and 0.7%, respectively, with older age and obesity more frequent in the hospitalised group.

Conclusion: COVID-19 presents in a similar way to other mild community-acquired respiratory diseases, but the presence of fever, anosmia and ageusia can assist the specific diagnosis. Most patients recovered without requiring hospitalisation with a low fatality rate compared with other hospital-based studies.

Keywords: epidemiology; infectious diseases; primary care; public health.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Age Factors
  • Brazil
  • COVID-19 / complications
  • COVID-19 / diagnosis*
  • COVID-19 / physiopathology*
  • Child
  • Cohort Studies
  • Cough / etiology
  • Cough / physiopathology
  • Fatigue / etiology
  • Fatigue / physiopathology
  • Female
  • Fever / etiology
  • Fever / physiopathology
  • Headache / etiology
  • Headache / physiopathology
  • Hospitalization / statistics & numerical data
  • Humans
  • Male
  • Middle Aged
  • Primary Health Care / methods*
  • Prospective Studies
  • Reverse Transcriptase Polymerase Chain Reaction / methods
  • SARS-CoV-2
  • Sex Factors
  • Young Adult