Thank you for taking part in the interview. We would also like your help with the next part of the study that involves you collecting a urine sample. We very much hope you will agree to give a sample, as this is an important part of the study. However, you don’t have to give a sample if you prefer not to.

Why give a urine sample?

We would be very grateful if you would agree to provide the Natsal research team with a urine sample. The sample will be tested for some infections that can be transmitted through sexual activity, as well as other microbes that are harmless and live in the genital tract. It is important to know how many people have different sexually transmitted infections (STIs) in Britain to help plan for sexual health services. To do this, we need to get a true picture of the levels of infections by asking all participants of the Natsal study if they would be willing to provide a sample for testing.

Who is being asked to take part?

We are asking everyone taking part in Natsal to provide a sample, even if they are not sexually active or think they are at no risk of STIs. It is important that as many people take part as possible, as this will help us understand the true overall picture of STIs in the  population of Britain.

What if I have never had sex?

We are still interested in a sample from you if you have never had sex. Your sample helps us understand what is happening in the general population.

What do I have to do?

You will be provided with a kit that contains instructions and a container to collect the first part of your urine stream. This should be done in a bathroom and will only take a few minutes. If you have a face-to-face interview, you can hand the container back to the interviewer who will pack and post it for you. Otherwise, you will be provided with a pre-paid envelope and instructions about how to pack and post your sample yourself in a Royal Mail postbox. You will be able to ask the interviewer any questions you may have. To thank you for your co-operation, a £5 gift card will be given to everyone who provides a sample.

What will my sample be tested for?

The sample will be sent to certified laboratories and will be tested for the following:

Chlamydia and Gonorrhoea: These are infections that can be passed on through sexual contact. They can be treated with antibiotics, but if not treated can lead to problems such as infertility and can be passed on to sexual partners.

Human papillomavirus (HPV): This is an infection that can be passed on through sexual contact. HPV can cause genital warts or, in rare cases, can lead to cervical or other types of cancer. A vaccine to protect against common types of HPV is available.

Trichomonas: This is an infection that can be passed through sexual contact. It may be more common in women but can also be found in men and can be treated with antibiotics.

Mycoplasma genitalium (MGen): This is an infection that can be passed through sexual contact. However, we need more information about how common it is. At present, only people who have symptoms are tested and treated with antibiotics for this infection.

Microbiome: This is the term used for all microbes that live in the human genital tract. We want to know how the microbiome varies by age, gender, and sexual behaviour.

The tests above will never involve human DNA or human genetics. Sample collection and storage is controlled by the Human Tissue Act (2004). The samples may be sent to Natsal investigators and collaborators, including at the World Health Organization STI Reference Centre in Sweden and the Wellcome Sanger Institute in the UK.

What happens to the rest of my sample?

We will ask you separately for consent to store what is left over from your sample after the tests listed above have been done. If you agree, any remaining sample may be used for future studies investigating infections in the population, for example, when new tests become available. Stored samples will only be used for future studies if all necessary approvals and permissions have been obtained in advance. As before, any new studies will not involve analysis of human DNA or human genetics. The sample will not be labelled with your identifying information and researchers who want to use the stored sample will have to apply for permission. If you do not agree to the rest of your sample being stored for future studies, NatCen will inform the laboratory and it will be destroyed. You may still give a sample even if you do not wish any remaining sample to be stored for future use.

What happens to the results of these tests?

The test results will be linked to the answers given in your interview and the information will be used for research purposes only. The laboratory will not know your name or address. The data will be kept strictly confidential, and no results will ever be traced to you or given to you. All data will be dealt with according to the Data Protection Act 2018 and the UK General Data Protection Regulation (GDPR). For more information on how the information you provide will be used, please see the privacy information at

Why will my test results not be returned?

We will not return individual results to you because: (1) the tests are good enough to help us understand what is happening with these  infections at a population level, but they may not be as accurate as the ones used by the NHS to make a diagnosis. Testing through the NHS is the best way to find out if you have an infection that needs treatment; (2) we are testing for some infections and harmless microbes that do not need treatment; (3) not returning results means that we do not need to link your sample to your name and address.

What should I do if I am worried about having a sexually transmitted infection (STI) or about my sexual health?

If you have concerns that you may have been infected with an STI, we suggest you seek professional advice. Free testing for STIs, as well as free confidential advice about sexual health, cervical screening, family planning and contraception, can be obtained online or from your local sexual health or Genitourinary Medicine (GUM) clinic, your GP, family planning clinics, as well as some pharmacies and youth centres. The following website will allow you to find your nearest sexual health service:

The interviewer will provide you with more information about organisations near you and their telephone numbers; you can also visit their websites for further information.

The UK Health Security Agency (UKHSA - previously part of Public Health England) recommends sexual health check-ups for sexually active people every time they change partner. This is because STIs may be present without a person knowing or having symptoms.

What if I change my mind?

You can withdraw your consent to participate in this part of the study at any point in time by contacting NatCen Social Research using the details on this page. NatCen will inform the laboratory and the sample will be destroyed.

Your co-operation is very much appreciated

If you have any questions, you can contact NatCen Social Research by writing to 35 Northampton Square, London, EC1V 0AX; calling freephone 0800 652 4568 or emailing

Our team is from NatCen Social Research (NatCen), University College London (UCL), the London School of Hygiene and Tropical Medicine (LSHTM) and the University of Glasgow.