The primary objective of this study is to estimate the prevalence of the post-COVID-19 condition in confirmed mild, moderate, and severe COVID-19 adult patients in Hai Phong, Vietnam.

It is a cross-sectional study implemented in Hai Phong (Vietnam) by the Infectious and Tropical Diseases Department of Viet Tiep 2 hospital and the Department of Public Health of the Hai Phong University of Medicine and Pharmacy (HPMU).

The aim is to enroll moderate and severe COVID-19 patients from the 2 following provincial hospitals, Viet Tiep hospital and Kien An hospital, and mild COVID-19 patients from the community level in Hai Phong to assess the burden of post-COVID-19 condition in each patient group (mild, moderate or severe acute COVID-19).

835 participants are aimed to be interviewed through phone calls: 196 participants with mild disease, 289 participants with moderate disease, and 350 participants with severe disease. In case of suspected post-COVID-19 condition, the participant will be proposed to come to Viet Tiep 2 hospital for a study visit i) to confirm the post-COVID-19 condition, ii) to describe symptoms, iii) to evaluate the functional limitations related to the post-COVID-19 condition, and iv) to assess the determinants of the post-COVID-19 condition in patients with mild, moderate, and severe acute COVID-19.

Inclusion Criteria:

• Adults aged 18 years or more;
• With a history of documented COVID-19 as confirmed by either a positive SARS-CoV-2 RT-PCR or antigenic test, 3-12 months before inclusion;
• Hospitalised in Viet Tiep 2 hospital or Kien An hospital (tertiary care hospitals) with moderate or severe COVID-19 or registered in provincial CDC health system for mild COVID-19;
• Accepting to participate in the study;

Exclusion Criteria:

• Not able to understand or answer a quick phone questionnaire;
• Individuals who refuse or cannot come to Viet Tiep 2 hospital in case of the suspected post-COVID-19 condition.

The patients hospitalised in Viet Tiep 2 hospital or Kien An hospital for moderate or severe acute COVID-19 3 to 12 months before inclusion, or registered in the provincial CDC database for mild COVID-19 that occurred 3-12 months before inclusion.