How long is an omicron infection contagious?

US researchers have found out how long you have been contagious with the omcron variant of the corona virus.

Cambridge – Omicron variants of the coronavirus have been prevalent in Germany for some time. In view of the growing crown numbers, many people ask themselves the question: How long are you contagious after getting infected with the omicron variant? A study from the United States now shows how long people infected with the Delta (B.1.617.2) and Omicron (BA.1) variants of the corona are infectious.

To determine the number of infectious days, researchers led by Julie Boucau of the Ragon Institute in Cambridge analyzed corona data from a total of 66 people who were infected with the corona between July 2021 and January 2022. 32 of the infected people had contracted the delta variant, 34 were infected with omicron (BA.1). Only one person in the study showed no corona symptoms.

Corona variant: This is the time you are contagious with an omcron infection

The researchers used nasal swabs to determine corona variants and viral loads and were particularly interested in how long it took from the first positive PCR test to the time when corona viruses were unable to reproduce. The researchers found the following:

• For those infected with Delta, a median of four days lasted (values ​​ranged from three to five days).
• For those infected with omicron, it took a median of five days (values ​​from three to nine days).

Corona infection with omicron: Some people are infectious for more than five days

Some of the people infected with Omikron have therefore been found to be infectious for a significantly longer period of five days since the first PCR test – in Germany, however, only a five-day quarantine is required. The same goes for the United States, after which the US doctor Eric Topol point to Twitter: “How long do people lose reproducible Sars-CoV-2 viruses after an omicron infection?” asks Topol and, referring to the study, replies: “Many more than five days, which is the CDC guideline of five days after the start of symptoms or PCR tests contradict.

Epidemiologist and immunologist Michael Mina adds on Twitter adds a hint of “even worse”: “the median time to culture negativity was EIGHT days, considering the first PCR test was positive OR the onset of omicron symptoms.” In fact, a look at the study confirms this: at Delta, researchers see a median of six days (ranging from four to seven days) from the onset of symptoms or the first positive PCR test (whichever occurred for first) until the viruses no longer present were able to reproduce, with an omicron infection the median was eight days (with values ​​between five and ten days).

Corona study shows: how long are you contagious with Omikron?

This means that people who have been infected with Omicron (BA.1) can be contagious for up to ten days (counting from the onset of symptoms or the first positive PCR test), but not necessarily. In their study, the researchers point this out New England Journal of Medicine it was reported that they had only a few participants, which limited the accuracy of the study. Further studies are needed to obtain information on isolation times. However, one thing is certain for the researchers: “Our data suggests that some people infected with omicron or delta excrete viruses that are still able to replicate more than five days after onset of symptoms or a positive first test.” (Tanja Banner)