What you need to know:
- A century has passed since the BCG vaccine was introduced to combat tuberculosis. But in Kenya and beyond, millions of TB cases continue to emerge each year.
- Poor funding, insufficient resources and diminished political goodwill hinder the development of a more effective vaccine to fight what has become a global epidemic
‘Dear reader, my name is Christine Njoki. I am 24 years old and a digital marketer. This is my story on how I am fast going blind because of a curable disease.
“As the year began in 2019, I noticed that my eyes were not aligning properly and therefore, I was squinting whenever I tried reading signages on billboards.
At first I thought I just needed spectacles to correct the error that was developing but even after getting them, I still couldn’t read those posters, no matter how hard I tried. They always seemed blurry.
The situation prompted me to go back to my optician, who referred me to an eye clinic where I was prescribed an anti-inflammatory eye drop because the doctor who saw me said the dense, cloudy area that was forming around the lens of my eyes, resembled a cataract.
When he dilated my pupils, he could see some areas in the back of my eyes, which he suspected to be inflammatory and therefore advised me to use the eye drops to clear them.
I took the drops and faithfully used them for about three months. Initially, there was slight improvement but it did not last long and instead, my eyesight just got worse. I could not even read notes that I had written myself.
In 2020, when schools were abruptly closed due to the Covid-19 pandemic, I travelled from my rural home in Kakamega to Nairobi, where I was in school, and told my mother that my sight was worsening.
But she was reluctant to take me to a third doctor so I took the initiative and went to Lions Eye Hospital, where the doctor who saw me gave me the shock of my life. He told me he suspected I could be having tuberculosis of the eye, what he referred to as ocular TB.
Based on the questions he asked, I began realising that it was a possible explanation. In January 2020, my uncle succumbed to TB. That means there is a history of the disease in our family.
But it was the confirmatory test that indeed confirmed that I was losing my eyesight to a disease I thought only affected the lungs. Until my diagnosis, I always knew that the surest way of suspecting TB was if someone had a persistent cough. I also knew that TB affected the lungs.
Although I finished my treatment for TB drugs and treatment for the inflammation in my eyes back in March 2021, the doctor told me that since it was caught late, and the disease had eaten up a large portion of my sight, the success of treatment was pegged at only 45 per cent.
That means that as I speak, the blurriness in my eyes has come back and the doctors do not even know why. Some of them, who I went to for treatment, did not believe that I could have TB of the eyes because it is rare.”
Christine is one of the extremely few Kenyans diagnosed with a rare form of tuberculosis known as ocular TB, an infection caused by Mycobacterium tuberculosis, in the eye, around the eye or on its surface.
Normally, Mycobacterium tuberculosis bacteria causes pulmonary TB, a highly contagious infection that easily spreads from an infected person to someone else by breathing in air droplets from a cough or sneeze of an infected person. This predominantly attacks the lungs.
On the other hand, TB infection similar to what Christine has is known as extrapulmonary tuberculosis and occurs in organ systems other than the lungs. This type of TB can affect the kidneys, spine and even the brain.
At 24 years, Christine is about to lose her eyesight to one of the world’s oldest yet curable diseases.
Her doctors are racing against time to save what’s left of her vision after TB destroyed more than half of it, all the while trying their hand at every possible test and treatment to cure tuberculosis.
As the world marks World TB day on Thursday, researchers are decrying lack of funding and the willingness of manufacturers to take risks as some of the factors that continue to hinder the discovery of new, better vaccines.
Speaking at the virtual sixth global TB forum last month, experts said in contrast to Covid-19 candidate vaccines that saw governments “falling over themselves to purchase guarantees,” which meant that the risk involved in massive Phase Three trials was greatly reduced, little political will has been thrown behind TB vaccine trials.
For the first time in a decade, deaths from TB are rising in Kenya, with the ailment killing about 21,000 people in 2020, four times higher than those who have died from Covid-19 since the onset of the pandemic. This is equivalent to 58 Kenyans dying of TB every single day.
TB remains one the world’s deadliest infectious diseases, with statistics showing that the disease, which is spread from person to person through tiny droplets released into the air via coughs and sneezes, kills more people than HIV and malaria combined.
When a person develops active TB, symptoms may include a cough, fever, night sweats and weight loss. Someone with active TB can infect five to 15 others through close contact over the course of a year.
When a person is infected with tuberculosis, spread by the bacteria known as Mycobacterium tuberculosis, they may or may not develop disease initially, but when the immune system is unable to clear the bacteria, they may carry that organism with them throughout their lives in a latent state.
It can then be reactivated to cause disease and be transmitted to others.
The World Health Organization (WHO) revealed last October that Covid-19 had reversed years of global progress in tackling TB, and for the first time in over a decade, deaths had increased.
Kenya is one of the 30 countries with the majority (at least 83 per cent) of cases. Last year, around 140,000 people in Kenya were estimated to have TB, according to the Ministry of Health.
Nearly half of people with TB in Kenya last year were likely to have missed out on diagnosis and treatment.
According to the Ministry of Health’s National Tuberculosis, Leprosy And Lung Disease Programme Annual Report, an estimated 15 per cent reduction in case finding was “largely attributable to the pandemic”.
Left untreated, TB kills about half of those affected. The disease is airborne and can lie dormant in someone infected with the bacteria.
However, on July 18, 1921, a newborn child in Paris became the first person to receive an experimental dose of the Bacille Calmette-Guérin (BCG) vaccine for TB.
The inexpensive vaccine is widely available and remains the only licensed vaccine for TB that has been incorporated into the existing immunisation programmes across the world.
A century later, it is now the most commonly used vaccine in the world. It is also still the only licensed vaccine for the disease.
But experts say it has significant limitations and has not stopped the disease from being the second-leading cause of death among infectious diseases globally in 2020, after Covid-19.
The BCG vaccine provides moderate protection against severe forms of TB in infants and young children.
But there is also no vaccine that is effective in preventing the disease in adults, either before or after exposure to infection. This means that even though a significant portion of the world’s population has been immunised with BCG, a high disease burden remains.
Typically, vaccines work by replicating a natural immune response. However, when it comes to TB, there are unknowns around what an effective natural response is and around the bacteria’s ability to evade the immune system.
And while there has been significant progress in drug development, treatment remains a long, tedious process prone to lack of adherence, leading to drug resistance.
To eliminate the problem, experts are calling for development of new TB vaccines that can prevent disease in people who have been exposed to the bacteria and stop infection before they happen.
But poor funding, insufficient resources and diminished political will are among the things experts cite as reasons that have hindered the development of a new vaccine.
Bavesh Kana, head of the centre of excellence for biomedical TB research, University of the Witwatersrand, wrote in The Conversation: “Vaccine innovation is needed for TB because the protection provided by the existing vaccine wears off over time, and it’s not completely effective in adults.”
As it is, the TB vaccine pipeline is depleted with little progress of candidate vaccines through the pipeline in the last few years.
This is creating a serious problem for the next decade of vaccine development, warned Professor Mark Hatherill, director of the South African tuberculosis vaccine initiative (SATVI) at the virtual sixth global forum on TB vaccines.
Now, all eyes are on nine candidates who have progressed to phases 2 and 3 of the clinical trials. The candidates bring a sense of hope in the fight against the dreaded disease, which claims 1.5 million lives a year globally.
While there is hope, there is also caution. Prof Hatherill said it is worrying that there are only a few TB vaccine candidates in phase 1 should the phase 2 and 3 trials fail to materialise. Currently, there are only two Phase I and three Phase II TB vaccine candidates in the vaccine pipeline.
“The good news is that there are nine candidates in Phase IIb and Phase III efficacy trials variously for prevention of infection, prevention of disease, and prevention of recurrent TB indications,” said Prof Hatherill.
Successful phase III trials are usually required before medicines or vaccines are approved by regulatory authorities.
“The bad news is the shape of the pipeline is inverted. If we do not have a successfully efficacious vaccine from one of those nine candidates, there are very few candidates in Phase I and Phase II that would fill those positions in the next five to 10 years."
Prof Hatherill said, however, in spite of the lack of candidates, there was considerable diversity in the TB vaccine pipeline.
“We have a number of live attenuated and inactivated wholesale mycobacterial vaccines, a number of protein subunit vaccines as well as viral vectored vaccines.
“The reality is that unless we have a big hitter out of current efficacy trials in five or 10 years or less, then we are in big trouble... we are looking at new delivery systems but primarily we need new candidates to enter the pipeline from the preclinical stage.”
Two vaccine candidates have, however, grabbed the spotlight. In 2018, a vaccine candidate known as M72/AS01E vaccine made worldwide headlines when a proof-of-concept Phase IIb study showed 50 per cent effectiveness at preventing TB in infected adults, paving the way for a Phase III trial.
At the global forum, Prof Hatherill said part of the preparation for the Phase III trial is a study to determine how often the disease occurs in different groups of people and why, which is being conducted at 50 sites in 12 to 15 countries.
The study is scheduled to enroll more than 20,000 adolescents and adults between the age of 16 to 34 years and will focus on people with TB infection, as well as those without TB and people living with HIV.
Researchers are also studying another candidate called MTBVAC, which uses a weakened version of the TB bacteria.
The vaccine candidate has been in development for adults and newborn infants and is currently completing a Phase II dose defining safety and immunogenicity study in 99 South African newborns.