Development of vaccines    worksheet

Vaccines are not a new invention. One of the very first effective vaccinations against disease came from China about 1,500 years ago - and was widely used there to combat Smallpox.

Lots of things have surprised me over the last year, as COVID-19 swept around the world. One thing was how quickly few vaccines were developed to protect you against COVID-19. Another was that not everybody shared my desire to get vaccinated as soon as possible.

This ancient Chinese vaccine worked against smallpox. Like many diseases, smallpox jumped across to us humans from animals – almost certainly from an African rodent. We have strong evidence of smallpox existing in China, Egypt and India some 3,000 years ago.

Today, smallpox has been eradicated, but between the years 1000 and 2000 AD, it killed at least 10% of the world’s population. In the 100 years from 1880 up to when it was wiped out around 1980, it had killed about 500 million people. There were a few different varieties of smallpox, but the most common one had a death rate of 35%. And survivors had heavy scarring especially on the face, and other complications.

Now we humans do have an excellent and complex immune system that can fight off most diseases. In general, the immune system manufactures both chemicals and cells to specifically target, and wipe out, infections – whether it’s a bacterium as in meningococcal disease, or a virus as in smallpox, or yes, COVID-19.

The problem is that our immune system needs time to respond in full force. It usually takes a few weeks to manufacture brand-new chemicals and cells in response to a new infection – and in that short time, you could be dead.

So vaccines are designed to give your immune system a head start. They provide tiny a “taste” of the bad guy germ to trigger your immune system into making protective chemicals and cells, without you having to catch the disease first. Then your immune system quietly works away. In a few weeks or so, it has made chemicals and cells specifically that will target that germ. Then the immune system can sit back and relax, with that response memory safely stored away. Then, later, whenever the actual harmful germ comes along, that pathway swings back into action. Almost immediately, your immune system floods your body with protective chemicals and germs to fight the infection – and stop you from dying. You might not even notice that your immune system worked away in the background, and kept you alive.

In Europe, modern vaccination came from an English country doctor, Edward Jenner, in 1796. Back then, there was a disease closely related to smallpox called “cowpox”. Cowpox was very much milder than smallpox - much less scarring, with a much, much lower death rate. Jenner noticed that when the people who milked cows got cowpox, they nearly always survived, but most importantly, they also seemed to be permanently protected from smallpox. Jenner’s idea was to give people a tiny dose of cowpox. He crudely got the scab material from the cowpox, dried it, smeared it over the tip of a needle, and simply pricked the patient’s skin a few times with the needle – and it worked. Now the Latin word for “cow” is “vacca”, so this process came to be called “vaccination”.

Chinese medical texts from the late 800s describe an early form of vaccination, which was called “variolation”. Smallpox caused visible raised small scabs (the “smallpox”) to appear on the flesh of those infected. The Chinese doctors of the day would scrape off the top layers of the scabs, and dry them. Variolation was the blowing of these dried particles (containing the smallpox virus) up the nostrils. It deliberately exposed the patients to a very low dose of smallpox virus particles.

Back then in China, medical quality control was not particularly good. If you were lucky, you would a lot of dead skin and tiny amount of smallpox virus, but if you were unlucky, you could get lots of smallpox virus.

So the death rate from the Chinese variolation was about 1%. But that was much better odds than the 35% death rate from getting the actual smallpox virus. The 99% of those who survived the variolation had a far milder illness, than if they were infected naturally. The other upside is that they were then immune for life.

So for anybody who thinks that Ancient Chinese Medicines are the best option, then vaccines will 100% fit the bill.

Comprehension


1. Where and when were the first vaccinations developed?  

2. What disease was the target of these first vaccinations?

3. How did smallpox get into the human population?

4. How many humans died from smallpox in the 100 years after 1880?

5. What are vaccines designed to do?

6. What disease did Dr Jenner use to vaccinate people with?

7. What farm animal gave the name to vaccination?

8. How did the ancient Chinese doctors deliver their variolation?

9. What was the death rate for Chinese variolation?

10. What happened to the smallpox virus?

 

 

 

Vocabulary

Rodent

Eradicated

Scarring

Head start

Variolation

Fit the bill

 

Summary In 300 or more words write a summary of Dr Karl’s talk.