Healthcare

The Next Step in Typhoid Prevention: A Closer Look at Oral Vaccination

Typhoid fever, also known as enteric fever, is a life-threatening illness caused by the bacteria Salmonella Typhi. Every year, over 11 million cases of typhoid are estimated to occur globally, resulting in over 128,000 deaths. While typhoid can be effectively treated with antibiotics, prevention through vaccination is crucial to control the disease, especially in areas where sanitation and clean water access is poor. Conventional typhoid vaccines have shown to effectively reduce the burden of the disease. However, their administration through injection by trained healthcare workers poses delivery challenges in remote communities. An oral typhoid vaccine promises to be a game changer in curbing the menace of typhoid globally through its ease of administration.

What is the oral typhoid vaccine?

The oral typhoid vaccine contains live, attenuated Salmonella Typhi bacteria. After ingestion through the mouth, the bacteria colonize the intestine and induce immune responses without causing disease. Two types of oral typhoid vaccines are currently available – Ty21a and Vivotif. Ty21a was the first licensed live, oral typhoid vaccine. It contains a bacterial strain that has been genetically altered to become less virulent. Vivotif is another live, attenuated oral typhoid vaccine containing a Typhi strain with mutations that attenuate its virulence. Both these vaccines are administered in enteric-coated capsules that protect the live bacteria from stomach acid until they reach the intestine.

Efficacy and dosing regimen

Clinical trials involving thousands of individuals have proven the efficacy of oral typhoid vaccines. Ty21a provides around 50-60% protection for 3 years after three doses. A booster dose may extend protection to 7 years. Vivotif provides around 55-60% protection for 2 years initially after three doses. A single booster dose increases efficacy to 83% protection for 3 years. Both vaccines have a 3-dose primary schedule – day 1, day 3 and either day 7 or 14 depending on the vaccine. The ability of oral vaccines to induce moderately long term protection with such a simple and easy dosing regimen sets them apart from injectable typhoid vaccines which require yearly or biennial boosters.

Safety and acceptability

The live but attenuated bacterial strains in oral typhoid vaccines are well tolerated. Common reported side effects include mild abdominal discomfort, nausea and low-grade fever after vaccination, lasting 1-2 days. Serious adverse events are extremely rare. Oral administration eliminates needle fears and needlesafety issues associated with injectable vaccines. This improves acceptance and coverage rates in communities skeptical of injections. In addition, oral vaccines do not require trained healthcare workers for administration, enabling use even in remote populations with limited access to healthcare. Overall, oral typhoid vaccines have a superior safety and acceptability profile compared to injectables.

Potential for impact

The simple oral route of administration and ability to self-administer without medical supervision are game changing advantages of oral typhoid vaccines. They offer the promise to reach undertserved remote communities currently lacking protective immunity due to poor healthcare infrastructure and access barriers. This impact can be amplified through school-based vaccination programs. With the inclusion of oral vaccines in routine immunization schedules of typhoid endemic countries, vaccination coverage rates can significantly increase to curb the spread of this debilitating and sometimes fatal disease in populations most at risk. Oral vaccines not only help control typhoid incidence but pave the way for its eventual elimination as a public health problem in developing regions. Their potential positive impact on reducing the global typhoid disease burden cannot be understated.

Role in typhoid elimination efforts

The World Health Organization’s Global Roadmap aims to reduce typhoid mortality by 75% and cut disease incidence by 50% by 2023 through coordinated control efforts. Achieving these ambitious targets will require deploying all available prevention tools, including typhoid vaccines. Oral typhoid vaccines are uniquely positioned to contribute effectively to elimination goals due to their delivery advantages over injectables. Their inclusion in national immunization programs and targeted vaccination campaigns can help plug critical gaps by reaching remote and marginalized communities left out of existing prevention efforts. Modelling studies indicate that when administered biennially in combination with other interventions like water, sanitation and hygiene improvements, oral vaccines alone could potentially interrupt typhoid transmission in endemic regions. Universal oral vaccination may even facilitate typhoid elimination in some settings. Hence, wider use of oral vaccines holds promise to fast track progress towards the WHO’s typhoid elimination agenda.

Challenges and future scope

While oral typhoid vaccines overcome important barriers to delivery and coverage compared to injectables, generating adequate awareness about them remains a challenge. Misperceptions around oral vaccines’ efficacy compared to injections also need addressing. Other constraints include limited inclusion of oral vaccines in high burden country immunization schedules due to funding availability and prioritization issues. High upfront costs currently impact their widespread use in public health programs. Future research should explore strategies to extend oral vaccines’ protection duration and develop affordable temperature-stable formulations for ease of mass administration in tropical developing regions where typhoid is highly endemic. Continued investment by global health agencies in enhancing oral vaccine availability, especially in resource poor countries, will be key to realizing their full potential in helping achieve the vision of a typhoid free world.

In summary, the advent of easy to administer oral typhoid vaccines offers promising options to check the high disease burden, especially in remote communities lacking healthcare access. Their inclusion as cornerstone prevention tools along with water, hygiene and antibiotics can help accelerate progress towards global typhoid elimination targets. With concerted efforts towards improving awareness, affordability and delivery at scale, oral vaccines hold the potential to radically transform typhoid control for generations to come.

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  1. Source: Coherent Market Insights, Public sources, Desk research
  2. We have leveraged AI tools to mine information and compile it

Money Singh

Money Singh is a seasoned content writer with over four years of experience in the market research sector. Her expertise spans various industries, including food and beverages, biotechnology, chemical and materials, defense and aerospace, consumer goods, etc.