How vaccines are injecting new hope

How vaccines are injecting new hope

It’s time to be positive.  After nearly a year of social, economic and health upheaval caused by the coronavirus pandemic, a vaccine has emerged with the potential to put an end to one of the worst global pandemics in living memory.  Outstanding work from the combined team of US pharma giant Pfizer and Germany biotechnology company BioNTech has produced a vaccine “found to be more than 90% effective in preventing Covid-19” according to the press statement released on Monday. 

Wise voices are urging caution:  The vaccine will take time to produce in sufficient quantities; distribution of a product which needs to be stored at -70°C is an enormous challenge; and while the efficacy of the product has been demonstrated its longevity, how long any immunity lasts, remains an unknown.

The voices are right.  We should be cautious.  But it’s hard - after months of grim news about infection rates, mortality, the economy, a little euphoria is understandable.  After all, if we can solve a problem like coronavirus what issues can’t we tackle?

The announcement by Pfizer and BioNTech also opens the door once more on the wonderful, if sometimes maligned, world of vaccines.  According to the World Health Organisation vaccines save around 2 million lives per year.  They also save money, huge amounts of it.  Every £1 invested in vaccines is thought to save between £16 and £40 in lost productivity, healthcare costs and long-term impact on people living longer and healthier lives.  Some of the case studies are simply stunning.  Take polio for instance.  Vaccines have driven down the incidence of this brutal disease from around 350,000 in 1988 to just 33 cases in 2018, according to WHO.

But the one thing that the new coronavirus vaccine has thrown up are the subtle differences between different vaccines and how they are by no means all the same.  With that in mind, we thought it was worthwhile spending a moment to explain what they are and how they work.

The history of vaccines

Vaccines, the word and the medicine, were created by the English physician Edward Jenner in 1796.  He deliberately infected people with cowpox virus which generated immunity from the far more dangerous smallpox.  The word vaccine, which comes from the Latin word vacca, meaning cow, came from this first treatment.

How vaccines work

Vaccines work in lots of different ways, but all have the same end goal, to activate the immune system, preparing it to battle infection.  The ways viruses work are as ingenious as the people who created them: 

Live-attenuated vaccines

This type of virus goes all the way back to the work of Edward Jenner.  It works by introducing a live, if weakened, form of a germ to stimulate the immune response.  This approach has generated vaccines for smallpox, measles, mumps, rubella and chickenpox amongst other diseases. It generally provides long-lasting immunity but can have some health drawbacks as live viruses are being introduced into the body. 

Inactivated vaccines

Generally less effective than live viruses, this process uses a “killed” version of the germ.  They sometime require multiple doses to achieve desired immunity.  However, they are safer and easier to handle as they don’t need to be stored in a refrigerated environment which live viruses require. Used to protect against flu, polio and rabies. 

RNA vaccines

Possibly the most exciting development in vaccines to have emerged in recent years and the class of vaccines that has produced the Pfizer / BioNTech coronavirus vaccine.  These drugs consist of a genetic code (known as RNA) that contains ‘instructions’ to cells to produce vaccine antigens and generate an immune response.  The ability of these drugs to be specifically designed to be used against particular viruses, or strains of viruses, make them extraordinarily adaptable.  As has been widely discussed, one of the downsides of these viruses is the need to be stored at very low temperatures, around -70°C, until shortly before they are used.  

Subunit, recombinant, polysaccharide, and conjugate vaccines

These vaccines work by introducing just one part of a germ or virus into someone’s body.  These elements of the virus could be a protein, sugar or substances derived from the casing around the germ.  Used to protect against shingles, hepatitis B and whooping cough amongst other diseases. 

Toxoid vaccines

These deploy a harmful, or toxic, product produced by a germ to stimulate the immune response.  These vaccines protect against the effects of the disease rather than the germ, meaning it is possible to become infected but suffer no, or limited harmful effects.  Generally need multiple doses to create a sustained effect.  Protects against diphtheria and tetanus.