Wednesday, March 22, 2023

Is There A Tuberculosis Vaccine

When Is The Best Time For My Child To Have The Bcg Vaccine

Improved tuberculosis vaccine closer to reality

It is best for your child to have the vaccine within a few days of being born and up to 6 months old, but they can be vaccinated any time up to 5 years of age. If your child is older than 6 months, he or she will be tested first to see if they have TB. Depending on the results of this test, your child may be offered the BCG vaccine. Read more about tuberculin skin test.

Challenges For Tb Vaccine Development

There are a number of substantial underlying problems to be faced in developing vaccines with enhanced protective efficacy against TB. In contrast to a classical vaccine-preventable disease such as smallpox, recovery from infection with M. tuberculosis is not associated with sterilising immunity against reinfection after clearance of the original infection with antibiotics. Studies of the molecular epidemiology of TB indicate that reinfection with new strains of TB is more frequent than previously believed . Therefore, vaccines need to be more effective than infection with M. tuberculosis itself.

One-third of the population worldwide is estimated to be infected with M. tuberculosis, and therefore any new TB vaccine should be suitable for use in subjects pre-exposure, to prevent infection, but also post-exposure, to prevent the development of disease or as an immuno-therapeutic agent to act with antimicrobials to increase the rate of clearance of M. tuberculosis.

An additional challenge is that as a large percentage of the human population has already been immunised with BCG, and so any new generation vaccines against TB must also be able to protect the population that has already been vaccinated with BCG. Obviously, new vaccines must also be safe enough to be used in HIV-infected individuals .

Simultaneous Administration With Other Vaccines

BCG vaccine may be administered concomitantly with inactivated vaccines and live vaccines at different injection sites using separate syringes and needles. In a blinded, randomized trial, neonates experienced less pain when the BCG vaccine was administered prior to concurrent intramuscular hepatitis B vaccine. If not given concomitantly, a minimum interval of 4 weeks is recommended between administration of two live parenteral vaccines to reduce or eliminate potential interference from the vaccine given first on the vaccine given later. Live oral and nasal vaccines, like rotavirus vaccine and live attenuated influenza vaccine , may be given concomitantly with, or at any time before or after, live parenteral vaccines, such as BCG vaccine. Refer to Timing of Vaccine Administration in Part 1 for additional general information.

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How Close Are We To A New Tb Vaccine What Are Some Of The Promising Developments

We still have some way to go. Recently, there have been two promising developments.

The first is a study that demonstrates that re-vaccination with BCG does indeed provide protection against TB disease. This is exciting as BCG is an approved vaccine and if this approach demonstrates sustained durable protection, rolling out mass vaccination campaigns will be easier than starting with a novel vaccine.

The second comes from a study that demonstrates a new vaccine from GSK gave good protection in a clinical trial setting. In 2020, this vaccine was licensed to the Bill & Melinda Gates Medical Research Institute for continued development.

How Is The Tuberculosis Vaccine Made

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Known as BCG, the TB vaccine has been around since the early 1920s. It is made by weakening a strain of bacteria similar to tuberculosis that was first isolated in cows. This strain of bacteria, called Mycobacterium bovis, is similar enough to the human strain that vaccination with the bovine strain protects against disease caused by the human strain.

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How Far Away Are We From A New Tb Vaccine

Tuberculosis kills millions of people each year, but several recent advances in vaccine development are providing fresh hope.

One hundred years ago, a vaccine based on a weakened form of the bacterium that causes tuberculosis was given to a French infant, whose mother had died of TB shortly after his birth. This was the first use of the Bacillus Calmette-Guérin vaccine still the only licensed vaccine against a disease that has plagued humankind for thousands of years.

Less Common And Serious Or Severe Adverse Events

Serious adverse events are rare following immunization and, in most cases, data are insufficient to determine a causal association. Rare adverse events include local abscess formation and suppurative regional lymphadenitis . These occur more frequently among infants less than 12 months of age than among older children and adults. There is some evidence in adults to suggest that subcutaneous administration of vaccine rather than the intended intradermal route is associated with more frequent abscess formation. Very rarely, disseminated BCG infection may occur and can be fatal in approximately 1 in 1 million vaccinations. Fatal cases almost always involve children with primary immunodeficiencies.

Anaphylaxis following vaccination with BCG vaccine may occur but is very rare.

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Bcg Immunotherapy In Bladder Tumors

Intravesical instillation of BCG has been used to treat superficial bladder carcinoma and interstitial cystitis. Many reports have confirmed the efficacy of BCG in the treatment of transitional cell bladder cancers and have delineated its adverse effects. The exact mechanism of its antitumor activity is unknown, but live BCG provokes an inflammatory response that includes activation of macrophages, a delayed hypersensitivity reaction, and stimulation of T and B lymphocytes and natural killer cells.

Kim Connelly Smith, … Jeffrey R. Starke, in, 2008

Since Tb Is Increasing In The United States Why Isn’t The Vaccine Recommended For Everyone At Risk Of Catching The Disease

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The TB vaccine is good at protecting against the severe form of disease found in young children , but it is not as good at protecting against the lung infection commonly found in adolescents and adults. Because miliary TB is very uncommon in the United States, we do not routinely use the TB vaccine. The United States is one of only two countries that have never routinely used the TB vaccine .

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The Vaccine And The Tb Skin Test

A bottle containing BCG vaccine

People who have had the vaccine will often then have a positive result to a TB skin test. This makes it more difficult to establish whether someone has latent TB. This is one of the reasons that the vaccine is not used in some countries.5When is the BCG vaccine needed? – Vaccinations – NHS Choices, NHS choices

The skin test will often be given before vaccination. If there is a positive result to the skin test then the vaccination will not be given.6BCG vaccination – When it is needed, NHS Choices,

Technical Advisory Group On Development Of A Who Roadmap For Global Introduction Of New Tb Vaccines

The World Health Organization is seeking experts to serve as members one of the Technical Advisory Group on Development of a WHO Roadmap for Global Introduction of New TB Vaccines. This Call for experts provides information about theadvisory group in question, the expert profiles being sought, the process to express interest, and the process of selection.

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Mycobacterium Tuberculosis Counteracts The Innate Immune Response

M.tb is transmitted by airborne droplets from individuals with smear-positive pulmonary disease by coughing, sneezing, singing, or talking . M.tb reaches the lung alveoli where it is taken up by resident AMs, dendritic cells and other phagocytic cells. AMs are unique mucosal immunoregulatory cells that express various pattern recognition receptors , and are the preferred M.tb target cell for uptake . The mycobacterial pathogen associated molecular patterns are recognized by PRRs expressed at the surface of the AMs. The PRRs involved in M.tb detection are the Toll-like receptors, Fc receptors, complement receptors, and PRRs, such as C-type lectin mannose receptors, dectin-1 and scavenger receptors . Once the inhaled M.tb has been engulfed by AMs, there is a spectrum of clinical outcome which includes clearance: the pathogen will be cleared by the immune system, primary TB disease: the bacteria grow and multiply after infection, ultimately causing disease, latent M.tb infection: the bacilli become dormant and may never cause the disease, and reactivation: the latent bacilli reactivate at a point in time distant to the primary infection . Clearance of the pathogen is estimated to occur in up to 90% of cases although the immunological mechanisms responsible are not clearly defined .

Bcg Vaccine Safety Issues

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In the early years of the use of the vaccine there were some concerns about safety, and there was the Lubeck disaster. Subsequently for many years there was little concern about safety. However it is now considered that the use of the vaccine in children who are immune compromised, such as children with HIV, could result in them having an infection caused by the BCG vaccine itself. This is because the vaccine contains a live but very weakened form of a bacteria called Mycobacterium bovis. This is not the same bacteria though as the bacteria that causes TB in humans, which is called Mycobacterium tuberculosis.7BCG – the current vaccine for tuberculosis, WHO 8The Difference Between Latent TB Infection and Active TB Disease, CDC,

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Bcg Vaccine Is Processed By Antigen Presenting Cells To Activate Th1 Type Cd4 T Cells

BCG vaccine induced protection against tuberculosis has been analyzed mostly in mice since mouse strains are susceptible to tuberculosis to varying degrees, and immunological reagents for evaluating protection are readily available. Several studies show that subcutaneous immunization with BCG vaccine or its subunit vaccine leads to an expansion of both CD4 and CD8 T cells in mice. Of these, CD4 T cells seem to play a major role since CD4 knockout mice are extremely susceptible to tuberculosis, and BCG fails to protect against tuberculosis challenge among these mice . However, in most mouse models, vaccination with BCG reduces the bacterial loads of M. tuberculosis at best by a few logs in the lungs after aerosol infection without achieving sterility . This suggested that BCG vaccine is perhaps less than effective in generating the immune responses needed to eliminate tuberculosis. BCG is a safe vaccine that is routinely used in many developing countries for neonatal vaccination, and is amenable to genetic manipulation we hypothesized that efforts should be made to increase its immunogenicity by analyzing its fate in APCs.

Willem A. Hanekom MD, PhD, in, 2016

Older Children And Adults

Depending on the risk of acquiring TB, there may be benefits to vaccinating older children. A doctor experienced in the use of BCG can help decide if the vaccination will be useful.

In general, BCG is NOT given to adults but can be considered for healthcare workers who are likely to deal with large numbers of multi-drug resistant TB cases.

More information about BCG vaccine can be found in the patient fact sheet.

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Limitations Of Bcg Vaccine

A different type of vaccination should also be considered in order to better mimic the natural route of M.tb infection in the lungs and thus to induce a better immune response, a short review was recently published on this topic . The first aerosol vaccine clinical trial against M.tb was reported in 2014, and there are more studies underway. Ultralow dose M.tb challenge were performed in non-human primates and showed different outcomes between rhesus and cynomolgus macaques , underlying the importance of the choice of the animal model. Aerosol vaccine alone or in combination with other routes of immunization may improve immunogenicity against M.tb by directly targeting and training AMs to subsequent infections.

Functions Of The Technical Advisory Group On Development Of A Who Roadmap For Global Introduction Of New Tb Vaccines

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In its capacity as an advisory body to WHO, the AG shall have the following functions:

  • To provide independent evaluation of the scientific technical and strategic aspects of development of new TB vaccines intended for adults and adolescents, including the perspective of country and regional level decision making, regulatory approval,global policy development, commercialisation and uptake in LMICs
  • To identify daps and recommend priorities within the WHO and/or relevant technical unit
  • To advise WHO on the key elements/workstreams to be included in the WHO Roadmap for Global Introduction of New TB Vaccines intended for adults and adolescents, and how these can be structured into an integrated plan including which stakeholders areinvolved/leading various work packages for TB vaccine introduction and scale-up at national, regional and global levels
  • To review and make recommendations to WHO on the final draft of the Roadmap and how it can advance to implementation.
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    Who Should Have The Vaccine

    In the UK the BCG vaccine is not currently part of the routine childhood schedule. It is offered to those who are at higher risk of TB. The main risk groups for TB are:

    • Babies and children under 5 who live in an area of the UK with a high rate of TB . In some areas of London, for example, all newborn babies are recommended to have the BCG vaccine.
    • Having a parent or grandparent who was born in a country where there is a high rate of TB
    • Living for three months or more in a country where is a high rate of TB
    • Being in close contact for a prolonged period with someone who has pulmonary TB

    Babies and children under 16 in any of these risk groups will usually be offered the BCG vaccine. The BCG vaccine does not work well in adults, but those aged up to 35 may also be offered the vaccine if their job has a high risk of contact with people or animals infected with TB. Adults are often given a skin test before they are offered the vaccine. This is to check whether they already have antibodies to TB .

    People with a past history of TB should not receive the vaccine. This is because they have an increased risk of adverse reactions to the vaccine.

    Skin Testing Before Vaccination

    All people, except infants < 6 months of age, should have a tuberculin skin test before BCG vaccination. Only immunocompetent people who have induration of < 5 mm after a TST should receive BCG vaccine.

    The TST uses a tuberculin purified protein derivative. This causes a hypersensitivity reaction in people who have a Mycobacterium tuberculosis infection. Hypersensitivity reactions can also occur in:

    • people who are infected with other mycobacteria
    • people who have previously received BCG vaccine

    Health professionals must correctly administer and interpret the TST. Consult state or territory tuberculosis guidelines for advice.

    The measles virus inhibits the response to tuberculin. Tuberculin-positive people may become tuberculin-negative for 46 weeks after measles infection, and measles-containing vaccines have a similar effect. 6,7

    Because of this, the TST may be unreliable for at least 46 weeks in people who have received a measles-containing vaccine.

    Interferon-gamma release assays are a type of blood test that can detect M. tuberculosis infection, but the TST is still the preferred method of screening for tuberculosis, unless the person has previously received BCG

    See also Vaccine information and Variations from product information for more details.

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    M72/as01e Looks To Phase 3 Trials

    There are several challenges to developing effective TB vaccines. From the scientific side, there is a lack of immune markers for prediction of vaccine-elicited protection, requiring long and expensive efficacy trials, as well as an incomplete understanding of the nature of protective immunity to TB. For vaccine developers, market uncertainties and a long and expensive research timeline can be dissuasive.

    There are 14 vaccine candidates in clinical trials: two in Phase I, eight in Phase II and four in Phase III, notes the WHO report.

    In particular, the WHO report identifies ‘promising’ Phase 2 results from candidate M72/AS01E.

    The M72/AS01E vaccine candidate contains the M72 recombinant fusion protein, derived from two Mycobacterium tuberculosis antigens , combined with the Adjuvant System AS01 .

    It was developed by GSK in conjunction with IAVI.

    The vaccine was developed by GSK, with a Phase 2b trial of a two dose regimen conducted in TB-endemic regions in individuals aged 18-50 years old. The final analysis of the trial was released in 2019, demonstrating an overall vaccine efficacy of 50% during the three years after vaccination.

    In January 2020, the Bill & Melinda Gates Medical Research Institute obtained the license for continued development of M72/AS01E from GSK.

    Meanwhile, a Phase 2 safety and immunogenicity trial in people living with HIV is being conducted.

    The Institute will also shortly commence a large epidemiology study across a number of high burden countries.

    Recombinant Bcg As A New Vaccine Against Tb

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    Recombinant BCG techniques may be useful for the development of a more effective mycobacterial vaccine than the parental BCG now in use. Various strategies have been used to develop rBCG against mycobacteral diseases. One is based on rBCG producing large amounts of autologous protective antigens these supplementary antigens are designed to enhance immunity to other BCG antigens by increasing the expression of their genes, as is the case for the immunodominant TB antigens. Recombinant BCG vaccine expressing and secreting the 30-kDa, major secreted protein of M. tuberculosis, also referred to as -antigen and antigen Ag85B , is associated with better host survival after challenge than parental BCG in the highly demanding guinea pig model of pulmonary TB. Animals immunised with rBCG30 and then challenged with an aerosol of a highly virulent strain of M. tuberculosis survived significantly longer than animals immunised with conventional BCG .

    Alternatively, BCG genes that have been lost by deletion from parental M. bovis strain and that are important antigens can be restored. An example is the case of ESAT-6 deleted from region RD1 of BCG . Both these approaches are attractive for improving or adding antigens to BCG and could be important in conferring immunity against TB.

    In another approach rBCG have been constructed secreting diverse cytokines, including IL-2, IFN- and others, in an attempt to enhance the immuno-stimulatory properties of BCG .

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