The rapid antigen tests which can be administered at home are generally referred to as self-tests in Norway and are also known as rapid antigen or lateral flow tests.
According to NIPH, a home test can return a positive result early in the early stages of Covid-19 infection if both the nose and throat are used to take a swab sample, while the test can give a negative result when only taken from the nose.
As such, self-tests which take samples from only the nose will detect most infections but samples from both the nose and throat may detect a higher number of Omicron infections.
Improved knowledge of the tests has shown that, even for tests which ask for samples to be taken from just the nose, a swab from both the nose and throat will work slightly better, NIPH said in a statement on Monday.
As such, the health authority recommends taking samples from both throat and nose where possible, although those who find it difficult to swab from the throat can just take their sample from the nose. Children should still only test from the nose.
“Particularly adults with symptoms can therefore take samples from both the nose and throat when they do self-tests,” NIPH doctor Joakim Øverbø said in the statement.
The sample should be taken from the throat first and then the nose, or only the nose – but not from the throat only, Øverbø said.
When taking a sample from the throat, the test should be done in the morning before breakfast – that includes both food and drinks – or at least 30 minutes after any food or drinks. That is to avoid a false positive result because some food and drink can affect the result, NIPH writes.
If your lateral flow result is negative but you have recent symptoms of Covid-19, NIPH recommends you take a further test 2-3 days later.
“If your symptoms are mild you don´t have to stay at home between the first and second tests. But if you live with someone or are otherwise close to a Covid-19 positive person you should stay at home between the first and second home test if you have symptoms,” Øverbø said in the statement.