Coronavirus identified in 2019, SARS-CoV-2 (COVID-19), has caused a pandemic of
respiratory illness in which manifestation ranging from asymptomatic presentation to
critically illness with severe pneumonia, acute respiratory distress syndrome,
respiratory failure, or multiple organ failure. It may influence several aspects of
everyday life including the levels of Physical Activity such as walking, cycling, sports
or active recreation and, thus, has negative effect on general health and quality of
life. Recent findings demonstrate a relation between COVID-19 infection and impairment in
functional capacity, and suggest that may also be associated with an increased risk of
acute and post-acute death. Moreover, individuals who have been infected might suffer
long-term consequences as a result of their infection (Long COVID), for few weeks (short
term) or 10-20 weeks (medium term) or more than six months (long term) post-infection.

The current study is designed to assess changes in PA (overall and in four domains i.e.
daily occupation, transportation to and from daily occupation, leisure time activities,
and regular sporting activities) caused by COVID-19 infection (i.e. in the short term, 4
weeks post infection) concerning the pre-illness vaccination profile and the number of
infections/reinfections using a web-based validated questionnaire in a large population
of Greece. Investigators hypothesize that the impact of COVID-19 infection on PA levels
would be more pronounced in cases of repeated infections and/or in the unvaccinated
compared to the vaccinated individuals against COVID-19. With regard to the potential
burden of COVID-19 in functional capacity, investigators wish:

1. to detect changes on PA levels in recovered COVID-19 adults compared to the
pre-infection levels as a result of a post-effect impact;

2. to identify a potential relationship between changes of PA levels and pre-illness
vaccination profile along with individual's number of infection/reinfections so as
to detect correlations amongst different parameters.

The Greek version of the revised Active-Q (AQGR) which is a self-reported, online,
interactive physical activity questionnaire that assesses adult's habitual activity on
weekly basis (in four main PA domains: daily occupation, transportation to and from daily
occupation, leisure time activities, and regular sporting activities) is employed.
Regarding questions of medical treatment during COVID-19 infection, individual's number
of infection/reinfections and other relative parameters, additional questionnaire items
have been incorporated. In total, the current web-based questionnaire consisted of 60-67
questions, based on previous responses and follow-up patterns, and will be extensively
used to address the aims of the current study.