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Covid reinfection: how likely are you to catch virus multiple times?

The Guardian
The Guardian
 2022-01-21
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People return to work as Covid-19 Plan B measure to be scrapped in England. Photograph: Andy Rain/EPA

The report of a Spanish woman reinfected with Covid within 20 days fits with anecdotal reports of people testing positive just weeks apart, or having had the virus three or even four times. Children are also being seen with reinfections. We take a look at the science behind catching Covid multiple times.

What is a reinfection?

Reinfection figures tend to refer to the detection of a second, or subsequent, Covid infection, regardless of the variant involved. The risk of reinfection is likely to depend on a range of factors: for example, data suggests it is higher in unvaccinated people and potentially in those whose previous infection was more mild with a lower immune response.

It also depends on the variant: one expert said the risk of reinfection with Omicron soon after a first Omicron infection would be lower than Delta followed by Omicron, and how long ago someone was vaccinated. Experts say the dose to which someone is exposed may also be important.

The UK Health Security Agency (UKHSA) uses the definition of a possible reinfection as a case 90 days or more after a previous confirmed Covid infection, in part because it excludes those who simply shed the virus for longer after infection.

How many reinfections have there been?

According to the latest figures for England from the UKHSA, from the start of the pandemic up to 1 April this year there were 890,575 possible reinfections, of which more than 10,000 were third episodes .

Very few possible reinfections are “confirmed” as that requires genetic sequencing. What’s more, with few people in the community having access to tests in the first wave, many first infections may not have been counted.

“With the combination of being two years into the pandemic, a few rounds of antibody waning, two major waves of immune evasion by Delta and then Omicron, there’s fairly rampant reinfection,” said Danny Altmann, a professor of immunology at Imperial College London.

Is it easier to be reinfected with some variants?

In short, yes. According to scientists at Imperial College London , after taking into account a host of factors Omicron was associated with somewhere between a 4.38 and 6.63-fold higher risk of reinfection, compared with Delta.

The team add that this means protection against catching Covid arising from a previous infection within the past six months has fallen from about 85% before Omicron turned up to somewhere between 0% and 27%. The drop is not surprising given that Omicron has been found to have the ability to dodge the body’s immune responses to a significant degree.

Do Omicron reinfections happen in a shorter space of time?

Potentially, yes. UKHSA data shows that for cases with a specimen date between 1 November and 29 December 2021 there were 2,855 probable reinfections 29 to 89 days after a previous infection – although some of these may reflect ongoing detection from an initial infection.

While the UKHSA notes it is difficult to directly compare the situation between variants – as there are many important changing factors at play, including overall levels of immunity in the population – Omicron’s immunity-dodging powers are likely to play a role in these reinfections.

It is not yet clear how well immune responses to Omicron protect against a second Omicron infection, or infections with new variants. “I would expect the risk of a second Omicron infection is a lot lower than the risk of Omicron following Delta after all you have developed antibodies to the actual Omicron spike protein,” said Paul Hunter, a professor in medicine at the University of East Anglia.

Why has my child had Covid twice?

That could well be due to different variants: according to data from the Office for National Statistics released in December, school-age children with Covid at that time were much less likely to have Omicron than Covid-positive adults. In other words, a previous recent infection could well have been Delta, while their latest is Omicron.

Are reinfections milder?

That may seem logical given the body’s prior immune response, and Hunter notes data suggests the viral load in reinfections is lower than in primary infections, suggesting the disease may, in general, be less severe. However, the severity of a reinfection depends on many factors, including the variant involved and a person’s vaccination status.

ONS data suggests that when the Alpha variant became dominant, symptoms were less common for reinfections – but this reversed when Delta became dominant. When Omicron became dominant, data suggests people were just as likely to have Covid symptoms in their second infection as their first infection. “There’s no shortage of reinfections, some pretty severe, although not requiring hospitalisations,” said Altmann.

How many times can people get Covid?

Among those who have had Covid twice are the politicians Kier Starmer and Matt Hancock, while there have also been reports of people having a Covid infection three or even four times, some just a few weeks apart.

The UKHSA do not break down reinfections by episode, although they have identified some possible third reinfections. What is clear is that the longer Covid is with us, the more reinfections a person may potentially experience.

Comments / 128

Marissa Albertson
01-21

I’m vaccinated and I had delta in August and just got over omicron a couple days ago. They are seriously trying to scare people and making it sound like the vaccinated don’t get it more than once. The truth is, we know little about the virus and how to deplete it and that’s that. Once more people can understand that and see what other places are doing that is actually helping their people (not America, we need to look outward) then we can actually figure this out.

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Erin Kordelewski
01-21

The problem with the data is that people are not testing and just quarantining for the 5 days recommended 🤷🏻‍♀️ what’s the point of knowing if you have to quarantine regardless of vaccination or positive/negative result. No one cares anymore, it’s here to stay no matter what we do. Makes no sense my healthy kids have to miss school because they may or may not become sick…what planet are we on right now? I don’t remember relocating 🤔🤷🏻‍♀️🤦🏻‍♀️

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Common Sense Texan
01-22

The chances of catching it multiple times pretty high when you keep destroying your immune system with the shots 🥵. the pandemic is in that shot, I’ve never had the shot and I’ve never had Covid. So to a stew Peter’s podcast and get some real news! STOP with the shots!!

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