Friday June 10 2011
The Lancet has run a series of articles on the future of vaccines
News stories have extensively covered the possibility of a vaccine that could offer “new hope in the war on meningitis”. The Daily Mail said that the “first vaccine against deadly meningitis B will be available within months”, and The Independent said that the vaccine will offer “80% protection against the main causes of meningitis”.
The news stories come in response to a series of articles on vaccines published in the medical journal The Lancet. The articles discussed the likely developments in vaccine biology and discovery expected over the coming years. The series follows a pledge from the charitable Gates Foundation in 2010 that called for a new “decade of vaccines” to help protect the vulnerable against disease and suffering. The foundation estimates that if vaccine coverage could be increased to 90% worldwide, then the lives of 7.6 million children younger than 5 years old could be saved between 2010 and 2019. To address this new opportunity after the pledge, The Lancet brought together leading scientists working in vaccine development to lay out the hopes for the decade. The series did not specifically look at a new vaccine for meningitis, as some newspaper coverage may have implied.
What does the series cover?
The overview of The Lancet’s vaccine series highlights the way that immunisation programmes have helped to enormously reduce infectious diseases around the world, leading to a huge fall in illness and death rates worldwide. At the end of 2010, global health leaders recognised the importance of vaccines and made a commitment to make the coming ten years “the decade of vaccines”. They pledged to work towards ensuring new vaccine discovery, vaccine development and the delivery of vaccines worldwide, especially to the poorest countries.
Although the news headlines focussed on meningitis, The Lancet’s vaccine series attempted to lay out the plan for how new vaccines, and vaccine technology in general may develop over the coming decade. The extensive articles cover various issues, including scientific challenges in vaccine development, how vaccines are produced and distributed, child immunisation procedures and their future, financing of existing and newer vaccines, and social challenges including how the benefits of vaccines can be best communicated to ensure public trust and confidence.
What vaccines against meningitis are currently available?
Nearly all the news coverage focussed on meningitis and a possible vaccine against meningitis B. Meningitis is inflammation of the lining of the brain and spinal cord, which can be caused by infection from viral, bacterial and sometimes fungal organisms. However, bacterial infection is the most serious and most widely known form of meningitis. Bacterial meningitis can sometimes lead to complications in which bacteria invade the blood stream and cause blood poisoning (septicaemia).
There are several bacterial causes of meningitis. In the UK, the most common form is meningococcal meningitis, which is caused by a bacterium called Neisseria meningitidis. There are several strains of this infection, known as A, B, C etc. The current meningococcal vaccine in the UK is against the C strain of Neisseria meningitidis and has been widely offered to teenagers and young adults in the UK since that late 1990s. However, it offers no protection against other meningococcal strains, including strain B, which is more common.
The body’s defence mechanisms use special types of proteins, called antibodies, to recognise substances or molecules that are foreign to the body. These are known as antigens. When antibodies bind to an antigen, they trigger an immune response. Once an antigen has been encountered, the body is able to swiftly produce the necessary antibodies if it is encountered again in the future. This allows a quicker, more effective immune response. Vaccines prime the body with a dose of the antigen, which does not cause disease but allows the body to develop antibodies and therefore allow greater production should the person come into contact with the microorganism in the future.
The antigens on the surface of the B strain of meningococcal bacteria that causes meningitis can vary. This means that a vaccine may only target a proportion of these bacteria. This has traditionally made development of a meningitis B vaccine difficult. One of the papers in the series mentions that a current potential vaccine against meningitis B in development consists of three antigens that are present in several strains of meningitis B.
Other vaccines that offer protection against other bacterial causes of meningitis include the pneumococcal vaccine given as part of routine childhood immunisations. This gives protection against the common strains of Streptococcus pneumoniae (the second most common cause of life-threatening bacterial meningitis in the UK). Another such vaccine is the haemophilus influenzae type B (Hib) vaccination, also given as part of child immunisations.
For more information on other childhood and adult immunisation programmes, see the Vaccination Planner.
What vaccines are expected in the next few years?
The past 30 years are said to have witnessed “an unprecedented increase in new vaccine development”. Vaccines now protect against an increased range of diseases, with fewer vaccinations now needed and an improved level of vaccine purity and safety. New discoveries in the biology of vaccine development are being made all the time, which promise vaccines for different diseases and which work in different ways. Over the coming years, it is expected that vaccines will be given to specific population groups, such as children, pregnant women or elderly people. There is also hope for vaccines outside the area of infectious disease, such as vaccines that protect against cancer and autoimmune disease.
One paper discusses how progress and changes in vaccine development occurred from the 1980s to the present day. These changes included the use of different approaches to vaccine design (such as using killed microorganisms, live attenuated microorganisms, purified components of organisms, and conjugated subunits [sugar chain components]), as well as improvements in safety of vaccines against smallpox, polio, measles and whole-cell diphtheria, tetanus and whooping cough.
The authors say that targets for new or more effective vaccines include meningococcal B, respiratory syncytial virus (the cause of bronchiolitis in babies), new influenza and pneumococcal vaccines, and “lifestyle vaccines” that protect against HIV infection and other sexually transmitted diseases. It is also hoped that vaccines may be developed for a wider range of medical uses, such as to prevent cancers and Alzheimer’s disease. Additionally, they say vaccines and vaccination strategies will need to be developed to provide protection for very young babies, either through direct vaccination or through expanded vaccination programmes for pregnant women.
The researchers also highlight that the ease of modern international travel makes the threat of new pandemic infections more pressing, and that rapidly emerging new infections will require the development of new processes to control them.
How is vaccine technology changing and what other challenges are faced?
One paper discusses how, in the past, vaccines were largely developed by scientists identifying the antigens or components of the microbe that cause the immune response. However, as bacteria and other disease-causing organisms evolve, vaccine development faces more challenges as microbes are becoming highly variable. This means that it is not easy to develop a single vaccine that will be effective against all strains of a single microbe. This is also the case with natural immunity developed after infection. The person may be immune if they encounter the exact same microbe again, but high microbe diversity means that naturally acquired immunity is often ineffective.
Also, there are great challenges in generating vaccines to protect the people who are most vulnerable because of their age or underlying diseases. Therefore, future vaccine development faces wider challenges, including considering the role of genetics and environmental factors affecting individuals. This, in turn, may lead to “more personalised approaches” to developing new safe and effective vaccines, such as for use in people with specific genetic characteristics.
One article also focuses on the challenges of delivering vaccines on a large scale, such as vaccines against pandemic and seasonal flu. The authors say that, to ensure effective vaccines are delivered requires complex production methods, meticulous quality control and reliable distribution. Ensuring that people have access to and take the vaccines also requires collaboration between manufacturers, regulatory authorities and national and international public health services.
Important factors to consider include the scalability of immunisation programmes, the time taken for the first dose to become available after a pandemic is declared, and regulations and manufacturing requirements, such as distribution and flexibility. Manufacturing is made more complex by the need for different vaccine formulations for different countries and age groups. For vaccines where supply is insufficient to meet demand, prioritisation of target groups has often been used in the past to increase the effect of these vaccines.
How does the public perceive vaccines?
One of the articles discusses how social attitudes may not be in line with public health goals in the development of vaccines and immunisation programmes. For example, parents may worry about the use of new vaccines in their children.
Over the years, newspaper headlines have occasionally associated mass vaccination with individual fatalities or illness. The authors say that, at times, sensationalist reporting has provided an ungrounded and incorrect view of the situation, “inflaming public attitudes about the vaccine’s safety”.
Particular examples include the high-profile death of a 14-year-old who had recently received the HPV vaccine against cervical cancer, a pregnant Thai woman who had received the H1N1 flu vaccine and suffered a miscarriage, and the deaths of four children in Japan who had recently received vaccinations against pneumonia and meningitis. In these cases, there was no reliable evidence to back up public concerns. The editorial says that “with a more sceptical and questioning media, a more responsive way forward may be, for example, to anticipate public concerns by reporting background rates of possible adverse effects so that, if they do occur, the public (and media) are neither surprised nor alarmed”.
The series of articles says that the public needs to regain confidence in immunisation and trust the organisations responsible for the research, development and implementation of vaccines. One series paper discusses technologies that are being developed for the assessment of vaccine safety, with the aim of rapidly identifying potential safety issues. The authors say that the success of such measures will rely on effective implementation of vaccination programmes, in addition to improving public awareness about benefits and risks in a way that encourages confidence in vaccines.