Introduction Background and objectives. In early 2020 novel Coronavirus disease (COVID-19)
begun to spread from Asia to Europe and beyond forcing WHO to declare global pandemic.
Infected patients shed the virus for a median of 20 days. Up to 10% of COVID-19 infected
patients develop a severe form of disease requiring intensive care admission and some of them
die. SARS-Cov2 is encapsulated positive strand RNA virus that uses ACE-2 of type 2
pneumocytes as binding sites. It has been hypothesised (Gattinoni 2020 ICM editorial) that
initial hypoxemia caused by loss of primary injury to pulmonary vasculature leads to
hyperventilation and patients self-inflicted lung injury predominantly in lung areas of
increase stress and strain. In turn, later during the course of the disease, ARDS develops
with a typical restrictive pattern of a stiff, wet and recruitable lung. At presents there is
no evidence-based causative treatment of SARS-CoV-2 and there is a burning need of
randomised-controlled trials to find effective therapeutic strategies intervention.

Explanation of rationale: Chloroquine has been used for malaria treatment and
chemoprophylaxis, and hydroxychloroquine is used for treatment of rheumatoid arthritis,
systemic lupus erythematosus and porphyrias. Both drugs have in-vitro activity against
SARS-CoV, SARS-CoV-2, and other coronaviruses, with hydroxychloroquine having relatively
higher potency against SARS-CoV-2 known to be susceptible in vitro to exposure to
Hydrochloroquine. At the moment clinical trials are ongoing to test clinical efficacy in pre-
and post-exposure prophylaxis in SARS-CoV-2. In one highly cited French non-randomised
observational study by Gautret et. al., a significant reduction of virus carriage has been
observed in patients co-incidentally treated by Azithromycin in addition to Hydrochloroquine
as a part of initial empirical therapy of community-acquired pneumonia. Azithromycin is a
macrolide antibiotic, which binds to the 50S subunit of the bacterial ribosome, thus
inhibiting translation of mRNA. The positive-sense RNA viruses and indeed all genes defined
as positive-sense can be directly accessed by host ribosomes to immediately form proteins and
the effects of Azithromycin on this process are not known. No data are available at present
on the clinical efficacy of Hydrochloroquine alone or in combination with Azithromycin and it
is likely that any treatment affecting virus replication would only be effective if
administered early, before overt ARDS develops.

In the light of this, the investigators designed a trial in which a hypothesis is tested,
that early administation of hydrochlorochine alone or in combination with azithromycin can
prevent respiratory deterioration in patients admitted to intensive care due to rapidly
progressive COVID-19 infection.

Methods Trial design: Prospective, multi-centre, randomised, pragmatic, double blind trial
Participants: Eligibility criteria for participants: Adult (>18 years) within 24 hours of
admission to intensive care unit with proven or suspected COVID-19 infection. For the purpose
of this study, intensive care unit is defined as a facility that allow continuous monitoring
of vital functions and oxygen administration . It is expected that most patients will have
rtPCR test known within 24 hours of admission to hospital. Nonetheless, if this is not the
case (eg. due to overloaded lab facility, lack of supplies) it is possible to randomise a
patient based on a strong clinical suspicion of SARS-Cov-2 infection. In case COVID-19 is not
confirmed in retrospect, experimental therapy is withdrawn and the study subject is withdrawn
from "per protocol" analysis of the primary and secondary outcomes, but remains in
"intention-to-treat" cohort for the analysis of safety. Exclusion criteria: symptoms of
febrile disease for ≥1 week, pregnancy, treatment limitations in place or moribund patients,
allergy or intolerance of any study treatment, incl. long QT syndromes, myasthenia gravis,
allergies or known deficiency of glucose-6-phosphate dehydrogenase, participation in another
outcome-based interventional trial within last 30 days, patients taking Hydrochloroquine for
other indication than COVID-19.

Settings and locations: Central study site is FNKV University Hospital Prague, updated list
of participating centres is listed in the appendix.

Interventions: Standard of care. All patients will receive best supportive care that will be
monitored, but not protocolised. It is recognised that in the standard of care may
substantially differ among study centres and that is why randomisation is stratified. The
standard of care also may change in time during the course of the study, for example, if a
new evidence emerges and changes the state-of-the art treatment recommendations. Any such
event will trigger emergency steering committee meeting, and decision will be taken about
further action. REB and regulatory authorities will be notified immediately about the
decision taken.

Study medication: All study medication is provided as a kind gift of Zentiva, ltd. Unblinded
study pharmacist will prepare into 40 mls of sterile water study medication, according to
patient's allocation into the treatment arm:

- Hydrochloroquine sulphate 200mg

- Azithromycin dihydrate 500mg

- Lactose 500mg (Placebo)

See enclosed Specifications of Product characteristics. The medication will be administered
in covered Jeannete syringe into nasogastric tube (for patients unable to swallowed) or drunk
from a black mug by patients who are able to. In both cases at least 50 ml of water will be
used for flush. Treatment group allocation is as follows:

STUDY GROUP HC-A Azithromycin Hydrochloroquine HC Lactose Hydrochloroquine C Lactose Lactose

Each study patient will be given:

- Day 1: Patients receive two doses 400 mg of Hydrochloroquine or placebo in 12 hours
interval and 500 mg of Azithromycin or placebo once in 24 hours (with the first dose of
hydrochloroquine or placebo)

- Days 2-5: Patients receive two doses 200 mg of Hydrochloroquine or placebo in 12 hours
interval 250 mg of Azithromycin or placebo once in 24 hours (with the first dose of
hydrochloroquine or placebo)

Adjusting IP administration to patients' swallowing capability and GI function:

During the study, 3 groups of patients will be enrolled. Those conscious and able to swallow
will be given study medication in black mug to swallow. Patients unable to swallow with a
nasogastric tube in place will be given the IP via the NG tube reconstituted in sterile water
and flushed as per local NG medication guideline. Administration of the IP is temporarily
omitted in patients who are unable to swallow but without NG access or do not tolerate any
enteral intake (such as patients in profound shock). As soon as the condition preventing IP
administration is eliminated, resumption of study medication follows the guidance for day 1.

Outcomes:

Primary outcome: Composite percentage of patients alive and not on end-of-life pathway who
are free of mechanical ventilation at day 14.

Secondary outcomes:

Composite percentage of patients alive and not on end-of-life pathway who are free of
mechanical ventilation at day 14 in the subgroup of patients without the need of mechanical
ventilation at baseline.

ICU-LOS D28 and D 90 mortality

Tertiary (exploratory) outcomes:

Viral load at D7 (No of viral RNA copies/ml of blood), proportion of patients alive and rtPCR
negative from nasal swab at D14, Difference of FiO2 ratio and respiratory system compliance
between day 0 and 7.

Changes to trial outcomes after the trial commenced, with reasons: None at presents Sample
size calculation: Based on data from Wuhan and Washington, where 67% of patients were dead in
2 weeks and half of the survivors needed protracted mechanical ventilation, the assumed
incidence of the primary outcome in the control group (ie. being alive and off the ventilator
in 2 weeks) to be 25%. The study gives us 80% chance to detect the increase of the primary
outcome to 50% in one or both interventional groups at p<0.017 with 74 patients in each arm.
In order to compensate for drop-out and low of follow up the plan is to enrol 240 subjects
into the study. An interim analysis is planned after the primary outcome is known for the
120th subject.

Randomisation: Will be performed in blocks of 3 and stratified for study centre and age
(above or at/below 70 years). Electronic Case Record Form (eCRF) will perform randomisation
using random sequence script in software R and generates medication code. Rationale:
Patient's age is single most powerful predictor of outcome and stratifying randomisation and
stratification decreases probability of treatment groups being of different age at baseline
by chance. In analogy, study centers may vary in the use of non-protocolised treatments,
which could bias the results.

Implementation:

Prior to initiation of each centre, the central research coordinator will train the local
dedicated study personnel in the use of e-CRF and other study procedures. The medication will
be delivered in sealed numbered boxes and stored in ICUs. Adhering to Good Clinical Practice
rules and guidelines is of upmost importance despite all the challenges during current
pandemic situation. Nonetheless, the eCRF has been designed to balance the safe conduct of
the clinical trial and feasibility of timely data entry during staff shortages and overload.
In order to do so, all data that is not essential for safety can be input in retrospect.

Collection data on cointerventions. Data on interventions that the investigators know/think
influence survival will be monitored and described. This include concomitant antiviral
antimicrobial diagnosis. Data will also be collected on how the respiratory specimen for
rtPCR diagnostic was collected (smear, endotracheal aspirate, bronchoalveolar lavage).

Statistical methods: Proportion of patients alive and off mechanical ventilation (primary
outcome) between intervention and control groups will be calculated using chi square test.
P-value is adjusted for multiple comparisons to p=0.017. Survival and ICU/length of stay will
be compared using Kaplan-Maier's curves and exploratory analyses my multi-level regression in
R. The plan is to analyse the primary outcome separately in patients who require mechanical
ventilation at baseline from those who don't and in patients above or below 70 years of age
as a priori subgroup analyses.

As mentioned above, primary and secondary outcomes will only be calculated in patients with
confirmed COVID-19 infection who received at least one dose of IP. Adverse events will be
calculated in all randomised patients (intention-to-treat analysis).

Ethical Considerations Benefits and risks. This trial investigates two drugs that are being
used off label to treat patients with severe COVID-19 with a balance of potential benefits
and harms. Potential benefit include good biological rationale and observational data to
believe that one or both drugs can prevent progression of a disease which led to death in 67%
of patients in similar condition to those in this study. Possible harms include QT
prolongation and resulting life-threatening arrhythmias or retinopathy, which may result in
blindness. The investigators believe that clinical equipoise regarding risk/benefit to
individual patient justifies well the conduct of this RCT.

Informed consent procedure. Patients with decision-making capacity will be asked to provide
written prospective informed consent (See Appendix I) to this protocol. It is expected that a
significant proportion of screened patients will lack the capacity to provide informed
consent due to altered consciousness, respiratory distress or sedation to facilitate
mechanical ventilation. In this situation, the deferred consent policy will be applied as per
local law: independent physician will confirm in writing that the patient lacks capacity and
fulfils criteria. Then, patient himself/herself are approached to provide consent as soon as
they regain capacity. They are given options to continue in the study, to withdraw with
permission to use the data collected up to the point or to withdraw from the study and
request deleting all data collected. Patient next of kin plays no formal role as surrogate
decision maker as per Czech legislature. Nonetheless, the family will be informed when
practical about their relative's enrolment into the trial and the family will be offered an
information leaflet explaining the nature of the study. All serious adverse event that are
suspected from being related to study interventions will be reposted to Research Ethics Board
and regulatory authorities as per local legislation.

Stopping rules. All SUSARs will be reported to both REB and to the steering committee, who
may decide to stop the trial for safety concerns. Apart from safety, other reasons for
stopping the trial are:

1. Emergence of new data ( e.g. publication of the results of a big RCT) that may lead
continuation of the trial unethical. This may be due to safety concerns of placebo group
(in case strong clinical benefit is proven by other trial) or any of the interventional
groups (e.g. if harm is reported by other trials). This rule also applies for emergence
of a new treatment.

2. After interim analysis: The steering committee will review primary outcomes and the
summary of adverse events in all 3 groups (labelled as A, B, C) whilst still blinded to
treatment allocation. The treatment can be stopped if the following criteria are
fulfilled:

1. There is a significant difference in the primary outcome at p<0.017 in between the
groups.

2. Futility: The futility criterion is not binding for the steering committee. Based
on available data the study statistician calculates the probability of being able
to prove the null hypothesis with achieving the target number of subjects and the
probability of type II error made by stopping the trial prematurely.

3. Safety: In case the number of adverse events in one or more treatment groups is
find uneven or unacceptably high.

Replication of key aspects of trial methods and conduct. The trial is designed to be fully
reproducible in larger international multi-centre trial.

Role of the sponsors This is investigator-initiated trial endorsed by Czech Society of
Anaesthesia and Intensive Care. The most significant resource for the study is unpaid
voluntary work of all the personnel conducting the study, who decided to do so in times of
worldwide pandemic crisis. Part of the resources were gathered from voluntary donors in a
crowdfunding campaign conducted by medical student association. Pharmaceutical company
Zentiva, ltd. was approached by investigators and kindly agreed to provide study medication
at no cost; however, it has had nor will have any role in study design; collection,
management, analysis, and interpretation of data; writing of the report; or the decision to
submit the report for publication.

Dissemination of Results: The investigators will submit the main results of the trial in an
open-access peer-reviewed journal within 3 months after 240th subject completed the 90-day
follow up visit, which is expected to happen in Q4 of 2021. The investigators will make fully
de-identified record-level raw data available in a public database.

Trial status: NOT YET RECRUITING (as of 1st April 2020)

Declarations:

The trial design is in accordance with Declaration of Helsinky and the protocol, care report
form and informed consent formularies were reviewed and approved by FNKV University Hospital
Research Ethics Board ("Ethical Committee") on 1st April 2020 (decision number KH
14-00-2020).