All over the world, people are locked into their homes wondering when they will next be able to sit in a cinema or hug the people they love. Who is putting together a rescue plan? I’m sure that people are wishing for one that might enable us all to get outdoors and back to work? Questions like this are in everyone’s mind and in every news bulletin. I suspect that businesses haven’t even begun to do risk assessments for their staff and customers yet.

The UK government is promising vaccines by September. Magic bullets eh? Is it possible or are they deluded? How difficult can it be to create a vaccine?

Let me explain!

Paul Ehrlich was a physiologist whose profound insight into how and why cellular and molecular mechanisms contribute to various pathophysiological states and disease. He theorised about “magic bullets” – even in the days before specific molecular interactions were worked out. His ideas led to the development of more vaccines and chemotherapy for cancer. He is a real hero! 

Vaccines to protect against viruses were some of the most important breakthroughs in the 20th century. we take them for granted today, but I’m old enough to remember the early 1980s. The days when governments were hoping vaccines for the common cold, herpes simplex and HIV would all be available soon. None of those attempts have been successful yet, so methinks the time is ripe for reminders about how difficult it is to conquer disease.

Do you know how long it took to develop enough vaccine for a global campaign to destroy one of the deadliest viruses the world has ever seen? It was an astonishing achievement! Smallpox is a terrifying disease –  one of the most contagious in the world – and it killed three in every 10 people who contracted it.

The Chinese were the first to attempt inoculation in the 16th century, but Edward Jenner from Gloucestershire was the first to publish evidence that vaccination against smallpox (variola virus) could be effective. His vaccination process – on 14th May 1796 – was crude and unsophisticated compared to 21st century vaccines but is worthwhile considering because it illustrates the principles of immunity and “magic bullets” so beautifully.

Jenner had noticed that milkmaids who’d recovered from cowpox didn’t ever show symptoms of smallpox (variola). In a famous experiment on a vulnerable child – which would never get past ethical scrutiny today – Jenner scratched the skin of his gardener’s lad (James Phipps). He scratched in some pus from sores on the hand of a dairy maid (Sarah Nelmes) who had cowpox. A few months later, Jenner challenged the boy’s resistance to smallpox; his immune system had adapted to the stressor (the virus) and he did not die.

Nevertheless, it wasn’t until May 1980 – 40 years ago this month – that the World Health Organisation was able to declare, with confidence, that smallpox was dead. The cowpox virus can jump the species barrier – from cows – hence the name vaccination (Latin vaccination=cow) and it causes a mild disease in humans that is similar enough to smallpox to confer immunity. Viruses can be unpredictable when they jump species barriers and today we are all living in the strange new land of lockdown because of a new virus – SARS-Cov-2 – which had the ability to jump the species barrier, probably from bats this time.

What do we know about the Coronavirus?

Vaccine development is usually based on mimicking the immune reaction of people who have recovered from the disease but it takes many, many years of painstaking work. Most vaccines are prophylactic – which means they induce immune reactions that are sufficient to prevent the person from showing the signs and symptoms of a disease. But the new virus has only been around for a matter of months:

• it is caused by SARS-COV2 a new coronavirus that emerged from the food markets in Wuhan, China
• the disease it causes is COVID-19 – a severe respiratory syndrome in more vulnerable people, but which is asymptomatic in the majority
• we don’t even know how many people have been infected in the UK because the track and trace system isn’t reliable yet
• scientists can’t predict how the disease progresses in people who have been infected
• there seems to be only one strain of the virus

SARS-COV2 is remarkably similar in its molecular structure to its more aggressive cousin SARS-COV-1 which caused a more aggressive severe respiratory disease about 20 years ago. Both viruses can infect other organs too – we need more post-mortem studies to determine which ones and in what way?

• The new coronavirus spreads rapidly and uses the same proteins as its cousin to enter cells of people who are infected.
• Every person who is infected can pass the virus to other people – but we don’t yet know the role of people who don’t show any symptoms of the virus.
• Even when symptoms do appear, maybe two weeks after being infected, who can remember who they had contact with a fortnight ago?

The best most of us can do is stay safely quarantined in our own homes in the meantime. Try not to complain about what you can’t do. Focus on what you can do.

And hope for a vaccine sometime soon.