Inclusion Criteria:  Any person > 5 years of age who tests positive to SARS-CoV-2 or is a household contact of someone of any age who tests positive is eligible for the trial. Index case must be within 72 hours of positive test. The positive test can be a RAT or a standard PCR nasal swab performed at an accredited laboratory for the diagnosis of COVID-19 as per the department of health regulations. If initial test is a RAT, then a a standard PCR nasal swab performed at an accredited laboratory for the diagnosis of COVID-19 as per the department of health regulations will be collected prior to randomisation but does not delay entry into the study awaiting the confirmatory result. All participants must provide a signed and dated consent form and for children < 16 years have a legally acceptable representative capable of understanding the informed consent document and providing consent on the participant's behalf. Consent forms will be developed in multiple languages and provided in a language that the participants are fluent in speaking. At least one other person other than the index case in each household must consent to participation to enable the consenting members of the household to be randomised. Household members who do not consent to participate in the randomised trial but whom consent to have their COVID-19 status recorded can contribute to outcome measures where relevant.  Exclusion Criteria:  Children Age < 5 years are excluded from being randomised to therapy but can contribute to the outcome measures if they are swab negative on day 1.  Documented Heparin allergy Previous documented heparin induced thrombocytopenia (HIT) Recurrent epistaxis that has required hospitalisation in last 3 months >72 hours since index case tested positive Inability to provide patient information and consent forms or study instructions in a language in which the patient is competent. Household members who are swab positive on day 1 are excluded from contributing to the primary outcome, but are randomised and still contribute to secondary outcomes