Immunity from Covid-19 vaccination versus the virus

Brittney Deguara, Stuff reporter​

A preprint study has emerged suggesting immunity following infection with SARS-CoV-2, the virus that causes Covid-19, may be better than vaccine-elicited immunity.

These findings have been used by some to suggest getting the disease is better than getting vaccinated. This clearly makes no sense.

Unlike immunity following infection, the vaccine doesn’t require you to risk getting severely ill from a disease that has already killed over 4.5 million people worldwide.

Before we unpack the new findings, let’s dive into what natural immunity is.

To start, medical professionals tend to refer to it as infection-induced or disease-induced immunity.

When you recover from Covid-19, your body creates little pathogen-fighting proteins called antibodies that can fight off future infections of SARS-CoV-2. Then, if you’re infected again, the antibodies can respond more rapidly and with greater strength than they did initially.

A similar thing happens when you get the vaccine. The first dose gives your cells background information on the virus so they can learn how to respond. The second dose then boosts and activates that memory response.

The study out of Israel - which is yet to be peer-reviewed - suggests natural immunity has longer-lasting and stronger protection against infection, symptomatic disease and hospitalisation caused by the Delta variant than two doses of Pfizer.

But this doesn’t mean people should be opting for infection over vaccination.

“While infection can induce a potent level of natural immunity, the risks associated with getting there are huge,” said Dr Nikki Moreland, a senior lecturer in immunology at the University of Auckland. “This virus can wreak havoc on the body.”

Other large studies found something different to the Israeli work.

Researchers from the United Kingdom found two doses from Pfizer or AstraZeneca were at least as protective as prior natural infection against Delta. To put it simply, you can get significant protection from a safe vaccine without the risk of a serious disease, death, or developing what’s known as long-Covid.

No matter the age, the potential health risks of Covid-19 are worrying. A preprint study out of Uruguay estimated age-specific frequencies of severe, critical and fatal disease.

For teenagers and those under 30, the risk of dying from Covid-19 is extremely low, but there is a risk of becoming severely ill and needing hospitalisation.

The longevity of natural immunity is still undetermined with research finding it to be dependent on disease severity and the variant. How long vaccine-elicited immunity lasts is also still unknown, but it’s suggested most vaccinated people may be protected long term.

On top of this, the Israeli pre-print study reported a single jab for recovered cases gave additional protection.

Several countries have already advised recovered cases to only get one jab, whereas New Zealand health officials recommend two jabs for everyone.

Eventually, immune memory fades - some people’s quicker than others - so booster shots might be helpful for everyone in the future.

So, what does all of this mean for recovered cases? You should still be getting two Covid-19 jabs to protect yourself and your whānau. Reporting disclosure statement: The University of Auckland’s Dr Nikki Moreland, an associate professor in immunology, Dr Nikki Turner, the director of the Immunisation Advisory Centre (IMAC), University of Otago professor Peter McIntyre, a specialist in vaccination, and the Ministry of Health provided expert advice for this post. It was also reviewed by The Whole Truth: Covid-19 Vaccination expert panel member Dr Maia Brewerton.