Rationale:

In the treatment, care and isolation of COVID-19 patients, one of the most important
issues is determining the duration of infectiousness. The current Dutch guideline advises
at least 14 days of isolation for seriously ill patients, which is the case for most
admitted patients, and at least 21 days for intubated patients. It is believed that in
most cases this isolation duration is too long, which is highly undesirable for patients
staying in closed single-occupancy rooms. This is known to result in limited contact with
healthcare workers (HCW) and to be associated with a higher level of depression among
patients. The longer the isolation, the higher the workload for HCW and the higher the
costs (e.g. with about 0.5 million admission days in the Netherlands, these work out at
about €14 million on personal protective equipment [PPE] and cleaning alone).
Additionally, isolation demands a larger healthcare workforce, yielding less capacity to
provide other care to non-COVID-19 patients, with numerous other consequences. On the
other hand, it is possible that some patients were discontinued from isolation too early,
leading to a risk of transmission to other patients and to HCW. In conclusion, duration
of isolation should be as short as possible for proper patient flow and to avoid
unnecessary burden to patients and HCW, and thus to healthcare in general. Therefore,
there is an urgent need to define the period of infectiousness of COVID-19. We will
develop a safe and effective algorithm for decision on timely discontinuation of
isolation of COVID-19 hospitalized patients.

Objective:

The ultimate goal of this project is to produce new evidence-based criteria for the
termination of isolation of hospitalized COVID-19 patients that are safe (very low
subsequent risk of transmission to other patients or healthcare workers) while reducing
the number of unnecessary days in isolation (thereby improving quality of life of
patients, reducing hospital costs, and making optimal use of the scarce number of
isolation beds). Multiple sources of data and evidence will be integrated to arrive at
these new criteria.

Study design:

This is a retrospective cohort and technical laboratory study.

Study population:

All adult COVID-19 patients tested positive in the 7 participating hospitals identified
between the end of February 2020 and December 2021.

Main study endpoint:

The main outcome of interest is the probability and the duration of being infectious in
hospitalized COVID-19 patients, consequently influencing the decision on cessation of
isolation.