Five ways our immune responses to COVID vaccines are unique

by Paul Gill and Menno van Zelm
Department of Immunology and Pathology
 excerpted from The Conversation 10 Sept 2020

The Oxford vaccine trial at the centre of safety concerns this week highlights the idea that people’s immune systems respond to vaccines differently.

We don’t yet know whether reports of immune complications in one or two trial participants have been linked to the COVID-19 vaccine itself, or if they were given the placebo vaccine.

But it does highlight the importance of phase 3 clinical trials in many thousands of people, across continents. These not only tell us whether a vaccine is safe, but also whether it works for people of different ages or with particular health issues.

So what are some of the immune factors that determine whether any of the 180 or so COVID-19 vaccine candidates being developed around the world actually work?

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Read more: Halting the Oxford vaccine trial doesn't mean it's not safe – it shows they're following the right process

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Our immune responses are all different

An effective vaccine should generate long-lasting protective immunity against SARS-CoV-2, the virus that causes COVID-19.

This can be by generating antibodies to neutralise the virus and likely also by helping the immune system memorise and quickly respond to infection.

How vaccines work with your immune system to protect against disease.

We know, from developing vaccines against other viruses, that people’s immune response to a vaccine can vary. There’s every reason to believe this will also be the case for a COVID-19 vaccine.

1. Vaccine type and how it’s delivered

Many COVID-19 vaccine candidates contain parts of the SARS-CoV-2 spike protein to stimulate protective immunity. However, there are many different ways of delivering these proteins to the body, and some may be more effective than others at stimulating your immune system.

For example, the Oxford vaccine combines the spike protein with another virus to mimic the actions of SARS-CoV-2.

Meanwhile, the candidate developed by the University of Queensland contains the spike protein packaged with another compound (an adjuvant) to stimulate the immune system.

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Read more: Oxford scientists: these are final steps we're taking to get our coronavirus vaccine approved

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Some people will likely need a follow-up booster shot to ensure longer-lasting immunity.

We may also see some vaccines delivered as a nasal spray. This may elicit a more effective immune response to COVID-19 in the upper respiratory tract, including the nostrils, mouth and throat.
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See the entire article at The Conversation, covering the remaining four topics:

2. Our previous infections
3. Our genetics
4. Our age
 5. Lifestyle factors