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CompletedNCT04481633PREPCOVUpdated Aug 10, 2026Results posted

Efficacy of Pre-exposure Treatment With Hydroxy-Chloroquine on the Risk and Severity of COVID-19 Infection

An interventional study of COVID 19 serology and COVID 19 Self-Questionnaire in COVID-19, sponsored by University Hospital, Toulouse. Completed at 12 sites in France. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-08-10.

Sponsored by University Hospital, Toulouse · Not applicable, Interventional, and Other

Phase
Not applicable
Study type
Interventional
Enrollment
547
Allocation
Non-randomized
Ages
18 Years and older
Sex
All
01

Study summary

There is a pandemic in the world by COVID-19. Currently, the pharmacological curative or prophylactic treatments for this infection are not known. Recent studies have suggested that Hydroxy-Chloroquine could be effective in vitro and in vivo against COVID-19. The main objective of this study is to assess in patients with autoimmune disease treated with long course Hydroxy-Chloroquine initiated before the pandemic COVID-19 had an independent protective effect on the risk or the severity of infection with COVID-19.

Read the detailed description

A pre- or post-exposure treatment strategy has been validated in some infectious diseases. In particular, in HIV infection, this type of prophylactic treatment reduces the rate of infection in at-risk populations. The first studies from Chinese show that in case of immunosuppression or immunosuppressive treatment, whatever the causal pathology, COVID-19 infection is more severe. The present study presents a population of patients with lupus (SLE) or Gougerot's disease (SGD) who are treated for a long time, with Hydroxy-Chloroquine. The protective effect against COVID-19 infection of Hydroxy-Chloroquine compared to populations not exposed to this drug requires to be assessed in patients and their control groups under or without immunosuppressive treatments.

It is hypothesized that long-term treatment with Hydroxy-Chloroquine in SLE or SGD taken in its usual indication before the onset of the pandemic could decrease the number of COVID19 infections and/or the intensity of the disease.

02

Conditions studied

  • COVID-19

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Keywords

  • lupus erythematous disease
  • prophylaxis
  • pre-emptive therapy
  • Hydroxy-Chloroquine
03

In context

COVID-19

7,640 studies on the registry are indexed under COVID-19; 488 are open to participants now.

This study's enrollment of 547 is above the median of 100 across 4,099 interventional studies indexed under COVID-19.

Browse COVID-19 studies →

Lead sponsor

University Hospital, Toulouse is the lead sponsor of 794 studies on the registry; 214 are open to participants now.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years and older
Sexes eligible
All
Accepts healthy volunteers
No

Inclusion criteria

Group with hydroxychloroquine treatment (HC +):

  • LED/SG diagnosed
  • Treatment with Hydroxy-Chloroquine in the 3 months before and during the outbreak at COVID 19, at least in December 2019. Patients may have treatment with immunosuppressants in combination with Hydroxy-Chloroquine.
  • COVID19 diagnostic questionnaire and available serology result.

Group without hydroxychloroquine treatment (HC-) :

  • No Hydroxy-Chloroquine intake for more than 12 months

    --> HC- without an immunosuppressant

  • Viral hepatitis C cured for more than 12 months or primitive bile cholangitis (CBP) whose diagnosis is based on international criteria.
  • Non-significant liver fibrosis assessed either by historical histology or by fibroscan with non-significant liver fibrosis Metavir - F3 (at last available examination)
  • No Hydroxy-Chloroquine, or immunosuppressants have been taken for more than 12 months.

  • COVID19 diagnostic questionnaire and COVID19 serology result available.

    -->HC- with an immunosuppressant

  • Diagnosis of LED/SG according to the CAB criteria revised in 1997 or autoimmune hepatitis according to the international criteria validated in 2008.
  • Patients treated with immunosuppressants for at least three months before the start of the pandemic at COVID 19, at least since December 2019.
  • COVID19 diagnostic questionnaire and available serology result.

Exclusion criteria

Exclusion Criteria:

  • Anti-CD20 or Cyclophosphamide taken during the six months prior to the completion of the COVID 19 serology.
  • Refusal of a blood test for antibodies to COVID-19.
  • Protected adults
  • Pregnant or breastfeeding women.
  • Lack of health insurance coverage
05

Study design

Phase
Not applicable
Primary purpose
Other
Allocation
Non-randomized
Intervention model
Parallel assignment
Masking
None (open label)
Enrollment
547 participants (actual)

Study arms

  • Other
    Patient treated with Hydroxy-chloroquine

    patients treated with Hydroxy-Chloroquine (HC) with or without immunosuppressants (IS)(HC+ group, n=400)

    Diagnostic Test: COVID 19 serology · Other: COVID 19 Self-Questionnaire

  • Other
    Patient without treatment with Hydroxy-chloroquine

    patients without treatment with Hydroxy-Chloroquine with or without immunosuppressants

    Diagnostic Test: COVID 19 serology · Other: COVID 19 Self-Questionnaire

Interventions

  • Diagnostic testCOVID 19 serology

    Diagnosis of Covid-19 past infection will be made by serology

  • OtherCOVID 19 Self-Questionnaire

    COVID 19 Self-Questionnaire

06

What researchers measure

Primary outcomes

  1. Number of Participants With Positive Anti-SARS-CoV-2 Serology

    Number of patients with positive anti-COVID19 serology depending on whether or not they were taking Hydroxy-Chloroquine

    Time frame: 12 months post inclusion

Secondary outcomes

  1. Number of Patients Who Experienced Symptomatic or Severe (Hospitalization) COVID-19 Infection

    Percentage of patients who experienced symptomatic or severe (hospitalization) COVID-19 infection, as determined by the self-administered questionnaire and medical consultation. Each subject will complete a self-administered questionnaire at the enrollment visit, describing the main symptoms of COVID-19 infection by answering "yes" or "no" to the various items. The physician will then conduct a medical assessment of the symptoms and their severity.

    Time frame: From inclusion until the end of the study (at M12)

Other outcomes

  1. Number of Patients With Anti-COVID19 Serology Indicating Effective Vaccine Protection

    Percentage of patients with anti-COVID19 serology indicating effective vaccine protection. Vaccine protection efficacy is measured by the presence of a post-vaccination antibody titer greater than 140 BAU/mL.

    Time frame: 12 months post inclusion

  2. Number of Participants With Elevated Post-vaccination Antibody Titer

    Rate of patient with elevated post-vaccination antibody titers according to treatment type and group

    Time frame: 12 months post iclusion

  3. Number of Patients Who Accepted the Anti-COVID-19 Vaccination

    Number of patients who accepted the anti-COVID-19 vaccination, which allows us to obtain the acceptance rate of the Covid-19 vaccination according to the 4 groups studied in the protocol

    Time frame: 12 months post inclusion

07

Results

Posted Aug 10, 2026
Limitations and caveats
* Study conducted by telephone (patients were not seen for a medical consultation) * No virological confirmation of COVID-19 infection * Bias related to the control group: inconsistent social distancing measures + group composed of people living in the same household * Short follow-up period

Participant flow

Participant flow — Overall Study
MilestoneHCQ+IS+ GroupHCQ+IS- GroupHCQ-IS+ GroupHCQ-IS- Group
Started112121115199
Completed505454112
Not completed62676187

Outcome measures

PrimaryNumber of Participants With Positive Anti-SARS-CoV-2 Serology

Number of patients with positive anti-COVID19 serology depending on whether or not they were taking Hydroxy-Chloroquine

Time frame:
12 months post inclusion
Reported as:
Count of participants · Participants
Number of Participants With Positive Anti-SARS-CoV-2 Serology
ParticipantsHCQ+IS+ GroupHCQ+IS- GroupHCQ-IS+ GroupHCQ-IS- Group
Number of Participants With Positive Anti-SARS-CoV-2 Serology31301230
Statistical analysis
  • HCQ+IS+ Group vs HCQ+IS- Group · Regression, Logistic · p = 0.014 · Odds ratio (or): 2.351 · 95% CI 1.188 to 4.651
  • HCQ+IS+ Group vs HCQ+IS- Group · Regression, Logistic · p = 0.118 · Odds ratio (or): 0.541 · 95% CI 0.251 to 1.168
  • HCQ+IS+ Group vs HCQ-IS+ Group · Regression, Logistic · p = <0.001 · Odds ratio (or): 0.171 · 95% CI 0.072 to 0.409
  • HCQ+IS+ Group vs HCQ-IS- Group · Regression, Logistic · p = <0.001 · Odds ratio (or): 0.197 · 95% CI 0.094 to 0.415
SecondaryNumber of Patients Who Experienced Symptomatic or Severe (Hospitalization) COVID-19 Infection

Percentage of patients who experienced symptomatic or severe (hospitalization) COVID-19 infection, as determined by the self-administered questionnaire and medical consultation. Each subject will complete a self-administered questionnaire at the enrollment visit, describing the main symptoms of COVID-19 infection by answering "yes" or "no" to the various items. The physician will then conduct a medical assessment of the symptoms and their severity.

Time frame:
From inclusion until the end of the study (at M12)
Reported as:
Count of participants · Participants
Number of Patients Who Experienced Symptomatic or Severe (Hospitalization) COVID-19 Infection
ParticipantsHCQ+IS+ GroupHCQ+IS- GroupHCQ-IS+ GroupHCQ-IS- Group
Number of Patients Who Experienced Symptomatic or Severe (Hospitalization) COVID-19 Infection2317718
Other pre-specifiedNumber of Patients With Anti-COVID19 Serology Indicating Effective Vaccine Protection

Percentage of patients with anti-COVID19 serology indicating effective vaccine protection. Vaccine protection efficacy is measured by the presence of a post-vaccination antibody titer greater than 140 BAU/mL.

Time frame:
12 months post inclusion
Reported as:
Count of participants · Participants
Number of Patients With Anti-COVID19 Serology Indicating Effective Vaccine Protection
ParticipantsHCQ+IS+ GroupHCQ+IS- GroupHCQ-IS+ GroupHCQ-IS- Group
Number of Patients With Anti-COVID19 Serology Indicating Effective Vaccine Protection486565119
Other pre-specifiedNumber of Participants With Elevated Post-vaccination Antibody Titer

Rate of patient with elevated post-vaccination antibody titers according to treatment type and group

Time frame:
12 months post iclusion
Reported as:
Count of participants · Participants
Number of Participants With Elevated Post-vaccination Antibody Titer
ParticipantsHCQ+IS+ GroupHCQ+IS- GroupHCQ-IS+ GroupHCQ-IS- Group
Number of Participants With Elevated Post-vaccination Antibody Titer22362541
Other pre-specifiedNumber of Patients Who Accepted the Anti-COVID-19 Vaccination

Number of patients who accepted the anti-COVID-19 vaccination, which allows us to obtain the acceptance rate of the Covid-19 vaccination according to the 4 groups studied in the protocol

Time frame:
12 months post inclusion
Reported as:
Count of participants · Participants
Number of Patients Who Accepted the Anti-COVID-19 Vaccination
ParticipantsHCQ+IS+ GroupHCQ+IS- GroupHCQ-IS+ GroupHCQ-IS- Group
Number of Patients Who Accepted the Anti-COVID-19 Vaccination768386148

Adverse events

Collected over From enrollment until end of follow-up, up to 12 months. Non-serious events are listed at a 5% frequency threshold.

Adverse event summary by group
GroupDeathsSeriousOther
HCQ+IS+ Group0/112 (0%)0/112 (0%)0/112 (0%)
HCQ+IS- Group0/121 (0%)0/121 (0%)0/121 (0%)
HCQ-IS+ Group0/115 (0%)0/115 (0%)0/115 (0%)
HCQ-IS- Group0/199 (0%)0/199 (0%)0/199 (0%)

Baseline characteristics

Age, Continuous
Age, Continuous(Years)HCQ+IS+ GroupHCQ+IS- GroupHCQ-IS+ GroupHCQ-IS- GroupTotal
Mean47.50 ± 13.2345.73 ± 13.6055.52 ± 30.4761.47 ± 12.1453.95 ± 19.17
Sex: Female, Male
Sex: Female, Male(Participants)HCQ+IS+ GroupHCQ+IS- GroupHCQ-IS+ GroupHCQ-IS- GroupTotal
Female10410790117418
Male8142582129
Race and Ethnicity Not Collected
Race and Ethnicity Not Collected(Participants)HCQ+IS+ GroupHCQ+IS- GroupHCQ-IS+ GroupHCQ-IS- GroupTotal
Count of participants————0
Polymedicated patient
Polymedicated patient(Participants)HCQ+IS+ GroupHCQ+IS- GroupHCQ-IS+ GroupHCQ-IS- GroupTotal
Count of participants72496071252
08

Study locations

12 sites
  • Limoges university Hospital
    Limoges, 87042, France
  • Montpellier University Hospital
    Montpellier, 31295, France
  • Pitié Salpêtrière Hospital - Hépatologie
    Paris, 75651, France
  • Pitié Salpêtrière Hospital - Médecine interne
    Paris, 75651, France
  • Haut-Lévêque Hospital - Gastro-entérologie
    Pessac, 33604, France
  • Haut-Lévêque Hospital - Médecine interne
    Pessac, 33604, France
  • Joseph Ducuing Hospital - Médecine interne
    Toulouse, 31027, France
  • Toulouse university Hospital - Larrey Dermatologie
    Toulouse, 31059, France
  • Toulouse University Hospital - Rhumatologie
    Toulouse, 31059, France
  • Toulouse University Hospital
    Toulouse, 31059, France
  • University Hospital of Toulouse - Rangueil Médecine interne
    Toulouse, 31059, France
  • University hospital Toulouse - Purpan Médecine interne
    Toulouse, 31059, France
09

References and documents

Publications

  • Alric L, Brusq C, Migueres M, Faure S, Lebray P, Viallard JF, Chauveau D, Sailler L, Berard E, Pugnet G, Cacoub P; Prepcov study. Evaluation of the effects of pre-exposure treatment with hydroxychloroquine on the risk of COVID-19 infection and on the efficacy of anti-COVID-19 vaccination during lupus or Gougerot-Sjogren's disease: Prepcov multicentre trial. Lupus Sci Med. 2025 Mar 5;12(1):e001435. doi: 10.1136/lupus-2024-001435. PubMed 40044500 ↗

Study documents

  • Protocol and statistical analysis plan · Oct 5, 2021

Documents are hosted by the registry — open the source record to download them.

Individual participant data

Plan to share: No

10

Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Aug 10, 2026, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
11

Registry details

Key details

Study ID
NCT04481633
Lead sponsor
University Hospital, Toulouse
Responsible party
Sponsor
First posted
Jul 22, 2020
Start date
Sep 9, 2020
Primary completion
Dec 6, 2022
Completion
Dec 6, 2022
Results posted
Aug 10, 2026
Last update
Aug 10, 2026

Study contacts

Laurent ALRIC, Pr
principal investigator · University Hospital, Toulouse

Oversight

Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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