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

People in the UK have reported positive tests for Covid just weeks apart in December and January, as well as having had the virus three or even four times. Children are being seen with infections. We looked at the science behind catching Covid multiple times.

A reinfection is what it is.

Regardless of the variant involved, reinfection figures refer to the detection of a second, or subsequent, Covid infection. It is possible that the risk of reinfection is higher in unvaccinated people and in people with a lower immune response.

One expert said that the risk of reinfection with Omicron would be lower if you had a variant that was Delta followed by Omicron. The dose to which someone is exposed may be important.

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

How many infections have there been?

The latest figures from the UKHSA show that from the start of the Pandemic up to 9 January this year there were over four hundred thousand possible reinfections, with over one hundred thousand of them found in the week ending 9 January.

Only a very small number of possible re infections are confirmed. Many first infections may not have been counted because few people in the community have access to tests.

Prof Danny Altmann, a professor of immunology at Imperial College London, said that 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.

Is it easier to be re-invade with some variations?

Yes, in short. Omicron was associated with a higher risk of re-infection compared to Delta, according to scientists at Imperial College London.

The team says that the protection against catching Covid has fallen from 85% to 27% since Omicron turned up. Omicron has been found to have the ability to dodge the body's immune responses.

Do Omicron reinfections happen in a short period of time?

Yes, it is possible. There were 2,855 probable re infections for cases with a specimen date between 1 November and 29 December 2021, although some of these may reflect ongoing detection from an initial infection.

Omicron's immunity-dodging powers are likely to play a role in these reinfections, as there are many important changing factors at play, including overall levels of immunity in the population.

It is not known how well the immune responses to Omicron protect against infections with new variations. Paul Hunter, a professor in medicine at the University of East Anglia, said that the risk of a second Omicron infection is lower than the risk of Omicron following Delta.

My child has had Covid twice this winter.

According to data from the Office for National Statistics, school-age children with Covid at that time were less likely to have Omicron than Covid-positive adults. Delta could well have been the cause of the recent infections.

The data shows that a small proportion of re infections are caused by people who tested positive for coronaviruses between 29 and 89 days after their previous infections. Many of these shorter interval reinfections are likely to be school-age children because they had the highest levels of infection in September and October.

Is reinfections milder?

The data suggests the disease may be less severe because the viral load in reinfections is lower than in primary infections. The severity of a reinfection depends on many factors, including the variant involved and a person's vaccination status.

The data shows that when the Alpha variant became dominant, symptoms were less common for reinfections. Data shows that people were just as likely to have Covid symptoms in their second infections as they were in their first. There is no shortage of reinfections, some severe, but not requiring hospitalisations.

How many times can people get Covid?

There have been reports of people having Covid infections three or even four times, and politicians like Matt Hancock and Kier Starmer have had Covid twice.

The UKHSA doesn't break down reinfections by episode. The longer Covid is with us, the more likely it is that a person will be re-infections.