The future of vaccination
Vaccination is one of the most successful forms of disease prevention available today, resulting in the complete eradication of diseases like smallpox and successful control of many others. However, there are still plenty of opportunities to make vaccines even better and to use them to control new diseases.
New ways of using and delivering existing vaccines are in development, while research continues into creating new vaccines to target an even broader range of diseases.
New technologies for vaccine delivery
For a vaccine to effectively stimulate a protective immune response, it needs to get past one major barrier: the skin, which is our body’s first line of defence against disease. This is why so many vaccines need to be injected under the skin into muscle.
A fear of needles can be a significant barrier for some people when it comes to getting a vaccination. Fortunately, new technologies are under development that will mean fewer injections (such as by combining several vaccines into one shot without impairing the immune response to any of them), or even technology that uses no needles at all!
Some vaccines can already be delivered orally (including vaccines for polio and rotavirus). Researchers are also working on innovative delivery methods such as needle-free skin patches and microneedle injection technologies for a less painful vaccination experience.
Most successful vaccines work by prompting our immune system to produce antibodies against a target pathogen and to generate long term memory so that a faster, stronger response occurs if re-exposed that same pathogen. However, for some diseases, standard approaches don’t work so well, either because our immune system does not respond as it normally would, or because a pathogen finds other ways around our defences. HIV/AIDS and malaria are two examples of diseases which are notoriously difficult to vaccinate against thanks to the pathogens’ ability to rapidly mutate and ‘hide’ from key parts of the immune system. Nevertheless, scientists are making progress on developing an effective vaccine against malaria and researching vaccines for HIV.
There are some infections associated with serious long-term complications that we don’t yet have a vaccine for. For instance, infection with the bacterium Helicobacter pylori means patients with peptic ulcers are more likely to develop stomach cancer, and group A streptococcus infection is responsible for rheumatic fever, which is still a significant cause of death and disability in developing countries.
The COVID-19 pandemic and vaccines
The scale of the COVID-19 pandemic has demonstrated the essential role of vaccination in today’s world. Several vaccines were produced and rolled out in vaccination programs globally within the first year after the start of the pandemic, compared with the previous average vaccine development time of 10 years or more. This reflects recent advances in vaccine technology that will also assist us in protecting against other infectious diseases, not just COVID-19.
For example, COVID-19 increased the speed of development of a new type of vaccine that uses messenger RNA (mRNA). Researchers have been studying mRNA vaccines for decades while investigating new or improved vaccines for influenza, Zika and Ebola, among other diseases; however, the mRNA-based vaccines for COVID-19 manufactured by Pfizer and Moderna are the first mRNA vaccines approved for widespread use.
Vaccines as treatment, not just prevention
Vaccines also have the potential to treat, in addition to preventing, both infectious and non-infectious diseases. Such therapeutic vaccines are being targeted at persistent infections, such as shingles and those due to human papillomavirus. They are also being targeted at non-infectious conditions, including autoimmune disorders, allergies, tumours and even drug addiction. In the case of tumours, vaccines may work by amplifying the body’s anti-tumour immune response. For autoimmune or allergic disorders, vaccines are being designed to switch off the unwanted immune responses responsible for these conditions.
Immunisation still has so much more to offer global health in both developed and developing countries around the world. Thanks to vaccination, we’re now so much closer to a world without polio—who knows what other diseases we might be able to eradicate forever in the future?