Can you catch Omicron twice? The key time gap between Covid reinfections and how long does immunity last

Covid cases are soaring again in Wales and the wider UK with more and more people testing positive to the virus.

Back at the start of 2022, there was widespread omicron cases in Wales with record breaking levels of infection. With some many people having caught the virus only recently many are wondering if they could become reinfected just a matter of months later.

To try and help understand whether this is possible WalesOnline spoke to professor of molecular medicine at the University of Kent Martin Michaelis. He explained that, due to how recently the omicron variant has emerged, it is hard to say for certain how likely reinfection is.

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Is there evidence that someone who has caught omicron can be reinfected?

“There are no hard data on this,” explained Professor Michaelis. “Typically reinfections are only considered if there is a time gap of at least 90 days between the initial infection and the reinfection. Since Omicron has not been around for very long, there are very little data on such infections.

“Generally, we know that people who had Covid-19 in the past can be reinfected. There are two reasons for this. The first one is that immune protection provided by the virus wanes over time. This means that although we are protected for a while after an infection, we will eventually become vulnerable to infection again. Some common cold coronaviruses have been shown to be able to infect the same person twice within 12 months.

“The second reason is that SARS-CoV-2, the virus that causes COVID-19, evolves and that so-called ‘immune escape’ variants emerge that are better at infecting people who had previously been infected with another variant (or vaccinated) . In this context, the Omicron variant is a particularly effective ‘escape variant’. “

Unfortunately, the original strain of Omicron is now been replaced by a different form which leads to even more uncertainty but also likely more reinfections.

Professor Michaelis added: “It is still difficult to tell to which extent an Omicron infection protects from another variant, but there seems to be at least some level of cross-protection. Moreover, there are now different Omicron sub-variants circulating. The original Omicron variant BA.1 seems to be in the process of being replaced by BA.2, and we will have to wait what this means for reinfections. The more variants are circulating at the time, the more likely it is that we see reinfections in a short time frame.

“We also need to be realistic with regard to what we can and cannot know about reinfections. To be sure that someone is really reinfected, they need to be closely monitored and the exact sequence of the virus that they are infected with needs to be determined This is very laborious and expensive and not routinely done.

“Nevertheless, we know that there is a correlation of disease severity and the level of immune protection in response to infection. People with very mild or no symptoms often have low and short-lived protection. In some people with mild Covid-19 symptoms, there does not seem to be a detectable antibody response after infection. Such people are then probably also not well protected from reinfection. Since Omicron causes more commonly milder infections than previous variants, it is possible and plausible, that more people can be reinfected with Omicron also after a previous Omicron infection. “

How soon after the initial Covid / Omicron infection could reinfection occur?

This is likely to be affected by the severity of the initial infection. “In patients with very mild Omicron disease that does not result in significant immune protection, said Professor Michaelis.” Reinfections may be possible within a short time such as a few months. “

Is there any evidence that reinfection is more likely with Omicron that it was with previous variants such as Delta?

The short answer is “we simply don’t know are this point. Professor Michaelis hypothesised:” Since Omicron causes more commonly mild disease than Delta, it appears plausible that the protection provided by Omicron infections is lower than that provided by Delta infections. However, hard data on this are not yet available. “


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