Shadowing Practice: Explanation of Vaccine Adjuvants - Learn English Speaking with Video

For our fourth lesson we're going back to where this all began

and we're talking about vaccines but specifically one component of vaccines that are known as adjuvants.

Now adjuvants are additives that are added to vaccines in order to stimulate the immune response

and typically they're added to most vaccines prior to their arrival at a pharmacy

but they can also be added right before you get

that injection and you can think of them like an alarm clock for our immune system.

They're telling our immune system to wake up, that we have something in our bodies that we need the immune system to respond to.

And they help by allowing more of our B

and T cells to create memory and antibodies against that pathogen that the vaccine is designed for.

Now for the past 50 years we've really used one main adjuvant and that's been aluminum salts.

And that's because those aluminum salts help to keep the vaccine in our bodies for a bit longer

so more of our immune system is able to respond to that vaccine.

But there's other types of adjuvants that are also used in the market, one of them being synthetic DNA.

So that DNA is made in the lab

and it's just very small pieces that is made to replicate little pieces of DNA that comes from viruses or bacteria.

So when it's in our bodies, our immune cells say, that's not supposed to be here.

They begin eliciting an immune response, but what they're actually eliciting in the immune response against is that vaccine that is now present in our bodies.

There's also a type of adjuvant called an emulsion

which is able to stimulate toll -like receptors

and these are proteins on the outside of our immune cells that once activated create a genetic response to release cytokines.

You can learn more about that in Sabrina's lesson on allergic reactions and the immune response.

Now if we use the COVID -19 vaccines as an example, we can see how sometimes adjuvants are or are not used.

The mRNA vaccines that were designed by Moderna or Pfizer -BioNTech

and the viral vector vaccines that were designed by Johnson & Johnson do not use any adjuvants.

So there's no aluminum salts, there's no synthetic DNA, there's no type of emulsions.

However, if we look at the protein subunit vaccine that does use an adjuvant, a saponin, and you can learn more about that in my Novavax explainer video.

So now that you have a better idea of what adjuvants actually are, stay tuned next week for our fifth episode where we're halfway through this science series,

and I look forward to seeing you there.

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Vocabulary and speaking notes for this lesson

This C1 speaking lesson is built on the video “Explanation of Vaccine Adjuvants”. The speaker keeps coming back to these words: vaccine, immune, adjuvant, response, Dna. This video has 28 sentences and 451 words to shadow. The speech runs for 2:35. The speaker talks at a natural 175 words per minute, close to everyday conversation. Only 80% of the words are among the 3,000 most common in English, so the vocabulary is demanding.

Key vocabulary in this video

The 15 most advanced words in the video, with pronunciation and meaning:

Word	Pronunciation	Meaning
vaccine noun	/vækˈsin/	A substance given to stimulate a body's production of antibodies and provide immunity against a disease without causing the disease itself in the treatment…
adjuvant noun	/ˈæd͡ʒəv(ə)nt/	An additive (often a separate product) that enhances the efficacy of a pesticide, but has little or no pesticidal effect itself.
aluminum noun	/əˈlu.mɪ.nəm/	American, Canadian, and Philippines standard spelling of aluminium.
elicit verb	/ɪˈlɪsɪt/	To evoke, educe (emotions, feelings, responses, etc.); to generate, obtain, or provoke as a response or answer.
emulsion noun		A stable suspension of small droplets of one liquid in another with which it is immiscible.
stimulate verb	/ˈstɪm.jəˌleɪt/	To encourage into action.
synthetic adjective	/sɪnˈθɛtɪk/	Of, or relating to synthesis.
additive noun	/ˈæd.ɪ.tɪv/	A substance added to another substance or product to produce specific properties in the combined substance.
antibody noun	/ˈæn.tɪˌbɑ.di/	A protein produced by B-lymphocytes that binds to a specific antigen.
bacterium noun	/bækˈtɪəɹ.ɪəm/	A single-celled organism with cell walls but no nucleus or organelles.
cytokine noun	/ˈsaɪ.təˌkaɪn/	Any of various small regulatory proteins that regulate the cells of the immune system.
explainer noun	/ɪkˈspleɪnə(ɹ)/	A guide that explains a topic.
pathogen noun	/ˈpæθəd͡ʒn̩/	An agent that can cause disease, especially an infectious microorganism, such as a bacterium, virus, protozoon or fungus.
saponin noun	/ˈsæpənɪn/	Any of various steroid glycosides found in plant tissues that dissolve in water to give a soapy froth.
subunit noun	/sʌbˈjuːnɪt/	Any subdivision of a larger unit.

Phrasal verbs you will hear

Word	Pronunciation	Meaning
go back to verb		To stem from; to originate in.
look forward to verb		To anticipate, expect, or wait for, especially with a feeling of approval or pleasure; to be excited or eager to.
wake up verb	/ˌweɪk ˈʌp/	To stop sleeping; to awake.

Pronunciation to watch

The speaker uses 7 contractions and reduced forms, such as they're, we're, we've. Say them the short way, as you hear them.

The “th” sounds: synthetic /sɪnˈθɛtɪk/, pathogen /ˈpæθəd͡ʒn̩/
Long words — get the stress right: aluminum /əˈlu.mɪ.nəm/, antibody /ˈæn.tɪˌbɑ.di/

How to practise with this video

Listen to the whole video once without speaking and note the words you do not know.
Start at 0.75× speed, shadow it sentence by sentence, then go back to normal speed once it feels easy.
Record yourself and compare with the original, paying attention to words like vaccine, adjuvant, aluminum.

What is the Shadowing Technique?

Shadowing is a science-backed language learning technique originally developed for professional interpreter training and popularized by polyglot Dr. Alexander Arguelles. The method is simple but powerful: you listen to native English audio and immediately repeat it out loud — like a shadow following the speaker with just a 1–2 second delay. Unlike passive listening or grammar drills, shadowing forces your brain and mouth muscles to simultaneously process and reproduce real speech patterns. Research shows it significantly improves pronunciation accuracy, intonation, rhythm, connected speech, listening comprehension, and speaking fluency — making it one of the most effective methods for IELTS Speaking preparation and real-world English communication.

Shadowing technique: read the full step-by-step guide →

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Vocabulary and speaking notes for this lesson

Key vocabulary in this video

Phrasal verbs you will hear

Pronunciation to watch

How to practise with this video

What is the Shadowing Technique?