Covid-19: Danish agency says infection can occur twice with Omicron variant

Two sub-variants of the Omicron variant of Covid-19  – known as BA.1 and BA.2 – are widespread in Denmark. Infection with one can occur in an individual with a previous history of infection with the other, researchers have found.

A file photo showing Danish Covid-19 test result history
A file photo showing Danish Covid-19 test result history on someone's phone. Photo: Bo Amstrup/Ritzau Scanpix

According to a report published by national infectious disease agency State Serum Institute (SSI) on Monday, infection with one subvariant of the Omicron variant of Covid-19 does not give full immunity against reinfection, since a different subvariant can escape immunity.

Around 2 million people in Denmark have tested positive for Covid-19 – almost a third of the population – since Omicron emerged in the country in November 2021, according to SSI.

The BA.1 subtype of Omicron is the most prevalent but another variant, BA.2, is gaining ground in many places worldwide, the agency writes.

“This pattern is reflected very clearly in Denmark. The majority of those infected with Omicron in December were affected by BA.1. However, in January, BA.2 gradually became ever more prevalent. This variant currently accounts for most coronavirus infections in Denmark, whereas BA.1 is now seen much more rarely,” SSI writes.

Gene sequencing of positive PCR tests by SSI detected “67 cases in which the same individual had become infected twice at a 20-60-day interval and where both infections were due to Omicron subtypes”.

In 47 of the 67 cases, the first infection was with BA.1 and the second with BA.2.

The majority of the reinfected individuals were “young and unvaccinated” according to SSI.

“Most experienced mild symptoms during their infections. The difference between the severity during their first and second infection was negligible. None of the infected individuals had become seriously ill, and none required admission to hospital,” the agency writes.

The SSI study shows that infection with two different Omicron subtypes “is possible” but “seems to occur relatively rarely in Denmark”, the agency writes.

Reinfections “have mainly affected younger unvaccinated individuals”, it also notes.

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Covid-19: Denmark registers under 1,000 cases in a day for first time in 2022

Fewer than 1,000 new cases of Covid-19 were registered by Danish health authorities on Monday, the first time since late 2021 the daily total has dropped to three figures.

Covid-19: Denmark registers under 1,000 cases in a day for first time in 2022

Monday saw 983 PCR tests for Covid-19 return positive results according to the national infectious disease agency State Serum Institute.

Not since October 19th last year, when 756 cases were recorded, has under 1,000 new cases of the virus been registered in a single day in Denmark.

The number of tests administered on a daily basis is now a fraction of what it was during earlier stages of the Covid epidemic in Denmark.

That is partly because Danish authorities no longer consider Covid-19 as a critical threat to society, but rather a dangerous infectious disease, meaning fewer measures are taken to reduce its spread.

As such, all restrictions relating to Covid-19 have been lifted and testing for the disease is now only recommended if there is a “special medical reason” for doing so.

READ ALSO: Covid-19: Denmark cuts PCR test capacity by 60 percent

The 983 positive cases were found among 8,109 PCR tests, giving a test positivity rate of around 12 percent.

747 people with Covid-19 are currently admitted to hospitals in Denmark. However, Covid-19 is not the reason for their admission in a large proportion of cases. The number of hospitalised people with the virus peaked at around 1,500 in early 2022. Early February saw daily new case numbers top out at around 55,000 per day.

15 people with Covid-19 are currently under ICU care in Denmark. Two of them are receiving ventilator treatment.