Database examples

Covid-19 reinfections not tracked in New Zealand as examples set to rise

Esmé Putt is back in bed with Covid-19 for the second time. After testing positive in April and returning negative results in the meantime, she got both lines again last week.

A positive rapid antigen test.
Photo: Unsplash / Annie Spratt

Although her symptoms have been milder, she still doesn’t feel well – one thing, however, has remained the same: “being really really really tired”.

“If I find a burst of energy again, then I’ll try to do something like watch a movie and about halfway through I’ll feel like a tank.”

Catching Covid-19 twice, especially within a 90-day window, is rare, but it can happen.

It can also happen that a person who has caught Covid-19 returns a second false positive test once and may have the flu instead.

This is what makes an official count difficult.

Although Putt recorded his two positive results online, the Department of Health (MOH) has no way of collecting this cross-data.

Michael Plank, professor at the University of Canterbury

Professor Michael Plank
Photo: Provided.

Professor Michael Plank of the University of Canterbury estimated that reinfections were low but would be on the rise.

“We may not see many reinfections yet and that may be because people may not feel like they need to test if they have had Covid-19 before” , Plank said.

“But it’s entirely possible that reinfections will only be a small fraction of the total number of cases at the moment – but that’s likely to change.”

Research was ongoing to find out whether reinfections resulted in mild, similar, or worse symptoms.

Associate Dean of the University of Otago (Pacific) and immunologist Dr Dianne Sika-Paotonu said early results showed it depended on the variant of Covid-19.

A British study showed that reinfections with the Alpha strain tended to be less severe compared to the primary infection.

But people who were reinfected with Delta or Omicron were more likely to show symptoms.

“However, ongoing work will be needed to better understand whether reinfections for Omicron and all its subvariants are more or less severe compared to the primary infection,” said Dr Sika-Paotonu.

GPs have noticed more and more patients are anxiously calling again with symptoms of Covid-19.

Royal New Zealand College of General Practitioners medical director Dr Bryan Betty said it was difficult to get an accurate picture.

“There is no doubt that some people are definitely re-infected.

“One of the puzzling features of the moment is that the symptoms of Covid are very similar to the symptoms of other viral illnesses – like the flu – so it’s sometimes a bit difficult to sort out what’s going on.”

The Department of Health said people who started showing symptoms of Covid-19 within the 90-day window of their first infection should not be retested as it may be inaccurate.

Instead, people who got sick again were told to stay home until they felt better.

Their household contacts still had to self-isolate again, unless they had had Covid-19 within the past 90 days, or had self-isolated as a household contact within the past 10 days.

The Ministry of Health is currently working on its case registration system so that it can officially collect reinfection figures.

This could be a useful tool in the future, as Professor Plank said reinfections were something that would likely continue.

“There is no guarantee that gravity [of Covid-19 subvariants] going to go down, but unfortunately I think it’s the reality for a lot of people that you’ll catch Covid multiple times over a long period of time – multiple decades.”