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Could you be a part of the battle against Typhoid and Paratyphoid fever?

BiVISTA - Bivalent Vaccination against Salmonella Typhi and Paratyphi A

You are invited to take part in a study to investigate whether a new vaccine that works by stimulating an immune response against Salmonella Typhi and Salmonella Paratyphi A can prevent paratyphoid A fever. In order to test if the vaccine works to protect against paratyphoid A fever, after vaccination with this experimental vaccine or a control vaccine, we will be challenging all participants with the bacteria that could cause paratyphoid fever.

We will also assess the immune response against Salmonella Typhi. The study is being run by the Oxford Vaccine Group, which is part of the University of Oxford, and multiple sites across the UK. The Serum Institute of India are funding the study.

If you are aged 18 to 55 years old, and in good health, then you may be eligible to take part in the study. We will provide reimbursement for your time, inconvenience, and travel. Participants will receive up to £4585 if they remain in the study for the entire period and attend all the scheduled visits required for them. The total study participation time is 7 months, during this time you will be required to attend the Oxford Vaccine Group for all study visits and on challenge day. We may also offer accommodation close to the Oxford Vaccine Group during the challenge phase, where facilities allow.

Background

Salmonella Typhi and Paratyphi A are bacteria that can cause a disease called enteric fever. Although they are from the same family as the Salmonella bacteria that cause gastroenteritis in the UK, they are quite different. Enteric fever is most common in low and middle-income communities in Asia with inadequate sanitation and limited access to safe water.

The bacteria are spread when infected individuals’ faeces contaminate food and water sources. Symptoms of infection include headache, fever, chills and general aches and pains. If not treated properly, enteric fever can lead to severe complications and even death. The infection mostly affects school-age children in Africa and Asia, but younger children can often become ill. It is estimated that globally 13 million cases of enteric fever happen every year, with over 130,000 deaths each year.

There are safe and effective vaccines against typhoid fever. However, there are no licensed vaccines against Salmonella Paratyphi A, that is responsible for around 3 in every 10 cases of enteric fever. There are vaccines in development, but designing a vaccine is difficult as it is not yet understood exactly what immune responses may protect individuals from disease.

The Serum Institute of India has developed this vaccine to protect against Salmonella Typhi and Salmonella Paratyphi A.

In this study, we hope to see if this experimental vaccine will produce an adequate immunological response against typhoid fever and we will also test if this vaccine can protect against Salmonella Paratyphi A infection. In addition, we will try to understand which parts of the immune response may be important in preventing paratyphoid A fever. We hope that the knowledge gained from this study will help in the development of vaccines and make paratyphoid fever a preventable disease.

To do this we will be giving participants either a dose of the experimental study vaccine or another vaccine as a comparator. One month after vaccination, we will be deliberately exposing participants to live Salmonella Paratyphi A bacteria. We do this by asking them to drink a solution containing the bacteria. We will then treat participants as soon as they show symptoms of infection, or 14 days after drinking the bacteria even if they don’t have symptoms. This process is known as a ‘challenge’ and has been safely undertaken by participants in previous Oxford Vaccine Group studies since 2011, including previous studies testing vaccines.

We know that by giving a specific dose of Salmonella Paratyphi A, approximately 60% of people exposed to the bacteria will develop paratyphoid A infection. By using this very controlled setting to expose people to Salmonella Paratyphi A, we can test vaccines to determine how well they protect against infection. If fewer people are infected with paratyphoid after receiving this vaccine candidate compared with the other vaccine, then we can estimate how much protection the vaccine offers against paratyphoid A infection.

The Oxford Vaccine Group, University of Oxford, is based in the Centre for Clinical Vaccinology and Tropical Medicine at the Churchill Hospital site.