Here’s why you don’t want to get Covid again

Thursday, 14 July 2022

Covid-19 Response Minister Dr Ayesha Verrall confirmed there would be no change to the traffic light settings.

Dr Siouxsie Wiles is a microbiologist and associate professor at the University of Auckland.

OPINION: I know we’re all over the pandemic. But wishing something wasn’t happening doesn’t mean it isn’t happening.

So, as we embark on our second Omicron wave, I want to tell you about an important new study that shows reinfection with Covid-19 is more debilitating and potentially deadly the second or third time around. The study report that’s currently available online is not yet peer-reviewed, but I still think it’s worth considering.

Ziyad Al-Aly is a clinical epidemiologist at Washington University School of Medicine. After seeing an increasing number of his patients getting reinfected with Covid, he decided to investigate how dangerous these reinfections might be.

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With the pandemic now in its third year, we already know that catching Covid-19 increases your risk of developing organ damage and of being hospitalised or even dying in the weeks and months after your infection.

Dr Siouxsie Wiles: “Artificial intelligence played an important part in discovering a potential new antibiotic. But it couldn’t have done it without the data generated from the enormous amounts of work put in by the researchers.”

What Al-Aly wanted to know was, does reinfection increase that risk even further?

To find out, he teamed up with Benjamin Bowe and Yan Xie from the VA Saint Louis Health Care System, part of a network of facilities that deliver healthcare to veterans of the US armed forces. The network also has an extensive electronic database which is updated daily.

Al-Aly, Bowe, and Xie searched the database for veterans who had tested positive for Covid between March 2020 and September 2021. After excluding those veterans* who died within a month of first testing positive, that left more than 310,000 who fit the bill. Of those, 38,926 had been reinfected by April of this year, some more than four times.

The researchers then searched the database for veterans with no record of testing positive for Covid. That gave them a control group of nearly 5.4 million people.

Next, they specified the health outcomes they were interested in based on previous Covid studies. Their list included deaths from any cause, hospitalisations, as well as disorders of various organ systems – though only if they came on during the follow-up period rather than something the veterans had experienced before the pandemic.

After crunching the numbers, the results were clear. Those veterans who had experienced two or more infections had more than twice the risk of dying and three times the risk of being hospitalised within six months of their last infection, compared to the veterans who only got Covid once. Those with repeat infections were also at higher risk of developing fatigue, diabetes, lung, heart, digestive, kidney, and neurological problems.

They also found that the more infections a veteran had, the more the risk increased. In other words, the risks are cumulative. Having two infections was riskier than one, and three were riskier than two. Interestingly, the risks were the same regardless of whether the veterans had been vaccinated or not.

It’s a pretty depressing study and shows this latest wave is going to put our health system under even more pressure in the months and years to come.

So please, let’s make wearing a mask when out and about as normal as wearing a seatbelt. We’ll all benefit in the long run.

Clarification: An earlier version of this story included a figure of 300,000, relating to veterans who had died within a month of first testing positive. This was an overestimate so has been removed. Updated 9.50am July 20.