SARS-CoV-2 infection in pregnancy is associated with an increased risk of adverse maternal and perinatal outcomes. One explanation is that the infection might increase the existing pregnancy-associated prothrombotic status, leading to a higher risk of placental and vascular complications. Administration of low-dose acetylsalicylic acid (LDASA) has shown to improve maternal and perinatal outcomes in women at high-risk of endothelial and placental complications. However, there are no data on the effect of LDASA in preventing complications in SARS-CoV-2- infected pregnant women. To reduce SARS-CoV-2- related complications in a highly vulnerable group to the infection, we will carry out this randomized, double-blind, placebo-controlled multicentre trial in 400 SARS-CoV-2-infected pregnant women. The study main objective is to evaluate the efficacy and safety of LDASA administered up to 36 weeks of gestation in SARS-CoV-2-infected pregnant women in reducing the incidence of adverse maternal and perinatal outcomes. Pregnant women tested positive up to 32 weeks of gestation with a SARS-CoV-2 rapid antigen or PCR test and agreeing to participate, will be randomised 1:1 to receive daily LDASA (125 mg) or placebo up to 36 weeks of gestation and be followed-up until delivery.

Inclusion Criteria:

• Pregnant women up to 32 weeks of gestational age

• Aged 18 years or older*

• Willing to deliver at the recruitment health facilities

  • In Mozambique, in case of age below 18 years, the participant will be asked for the assent and the informed consent will be given by the legal tutor in accordance with the national regulations.

Exclusion Criteria:

• On regular ASA treatment for pre-eclampsia prevention
• On long-term non-steroidal anti-inflammatory medication
• Bleeding disorders, mainly haemophilia, hypoprothrombinaemia orVon Willebrand's disease
• History of hypersensitivity to ASA or to any of the excipients of the investigational product.
• History of peptic ulceration, including active, chronic or recurrent gastroduodenal ulcer; recurrent gastric discomfort History of gastric bleeding or perforation after treatment with aspirin or other non-steroidal anti-inflammatory drugs
• Inability to cooperate with the requirements of the study
• Severe COVID-19 disease (with any of the following: respiratory rate > 30 breaths/min; severe respiratory distress; SpO2 ≤ 93% on room air; acute respiratory distress syndrome; sepsis with acute organ dysfunction).
• Treatment resistant hyperemesis gravidarum
• Hypersensitivity to nonsteroidal anti-inflammatory drugs or to tartrazine (cross-reaction) or to any of the excipients used in its composition.
• Asthma.
• Severe renal or hepatic insufficiency.
• Nasal polyps associated with asthma that are induced or exacerbated by aspirin.
• Severe COVID-19 disease (with any of the following: respiratory rate > 30 breaths/min; severe respiratory distress; SpO2 ≤ 93% on room air; acute respiratory distress syndrome; sepsis with acute organ dysfunction).
• Treatment resistant hyperemesis gravidarum

Study tablets will be identically packaged in small boxes. All study personnel, investigators and the participants will remain blinded throughout the trial.