Who may participate

This study is seeking healthy breastfeeding female participants.


Women of non-childbearing potential:

You may participate in this study provided that:

• You are between 18 and 55 and

• You have been surgically sterilised (bilateral oophorectomy, bilateral salpingectomy, or hysterectomy).

• OR you have an ovarian failure. If you do not fall into one of these categories (described above), you will be considered as capable of having children.

Women of childbearing potential:

At each visit to the PCRU, we will check that you are using the appropriate contraception. You must fulfil one of the following conditions:

▪ You have had a bilateral tubal occlusion

▪ You have a non-hormonal IUD

▪ You have a hormonal IUS

▪ Your partner has undergone a vasectomy at least six months ago

▪ You use implantable hormonal contraception

▪ You use non-implantable hormonal contraception

▪ You are abstinent from heterosexual intercourse as your preferred and usual lifestyle (abstinent on a long term and persistent basis) and agree to remain abstinent.

These contraception methods must be used until minimum 28 days after last administration of study medicine or until the end of the study. In addition, hormonal contraceptive methods will have to be started at least 28 days before the start of the study and non-hormonal contraceptive methods will have to be started at least 14 days before the start of the study.

If you use non-implantable hormonal contraception, you must add one of the below barrier methods in order to be eligible for study participation:

▪ Male or female condom;

▪ Cervical cap, diaphragm, or sponge;

▪ A combination of male condom with either cervical cap, diaphragm, or sponge (double-barrier methods).

In addition to the criteria listed, participants must meet the following requirements:

  • Weight of 50 kg minimum
  • Body Mass Index of min 17.5
  • Non-smoker, ex-smoker, smoker (max 5 cig/day)
  • Able to meet all study visit requirements. There are other requirements for participation in this study. The study staff will explain these to you during the screening process.


Healthy lactating women who agree to temporally interrupt breastfeeding their child for 4.5 days
18 - 55
The age a person must be to participate in a clinical trial.
The sex of people who may participate in a clinical trial. Sex is a person's classification based on assignment at birth. Eligibility based on sex is distinct from eligibility based on gender.
View more eligibility criteria

Each clinical study has its own guidelines for who can participate, called eligibility criteria. However, only the research study staff can fully determine if you qualify to enroll in the study.

What to expect

The study is planned to last for approximately 9 weeks.

Several examinations or procedures will be required in connection with the study:

1. A screening examination, during which you will sign a COVID ICD and the study ICD;

2. COVID-19 assessments during residence in the PCRU

3. One treatment period organized of 5 days and 4 nights in the PCRU (from Day -1 to Day 4).

4. The follow-up phone call will take place 28 to 35 days after the last administration of the study medicine.

You will not personally derive any benefit from your participation in this study, but the results obtained could be very important for the development of medicines and treatments which will benefit other people.

Long-term follow-up
a follow-up call at the end of the study
Some studies require the study team to stay in contact with the participant for a period of time after he or she completes the main part of the study. This long-term follow up is to collect additional information on the study drug over time.
How long is the study?
Approximately 9 weeks
The length of the study includes the time from screening until the final follow-up call or study activity. There may be up to 28 days between screening and dosing.
€ 1.670 upon completion of the study, €120 Covid and transportation fees
Participants in clinical trials at the PCRU receive financial compensation for their participation. The amount depends on factors like length of the stay, total number of study visits, and the nature of the study procedures.

Interested in participating?


New to clinical research? If you’re interested in becoming a participant or need more information on the registration process, please complete and submit the registration form. We will contact you as soon as possible 

Already in our database? If you’d like to subscribe for this study, please contact us by phone. 

Studies (recruiters) For more information, call 0800/99.256 (from abroad: 0032/2. 556.70.02 or 00800/2636.2636 from France, The Netherlands, Germany, UK) or email us.  

Personal data means any information relating to you as a natural person such as for example your name, your date of birth, your telephone number or information relating to your health or your medical condition.

The personal data you share with us when completing the registration form is collected by the Brussels PCRU in order to send you the relevant literature and the medical questionnaire. It will be processed in a strictly confidential manner and in conformity with all applicable legislations, especially the European and Belgian laws applicable to clinical trials, and the European and Belgian laws applicable to personal data protection.

Personal data protection is very important to our clinical research unit. That’s why we ask that you read our Privacy Notice available at https://privacycenter.pfizer.com/en/belgium.