The Omicron variant of the Corona virus has increased the demand for rapid home antigen tests. However, these tests brought up the question of whether the swab taken from the nose alone is sufficient.
According to some scientists, the Omicron variant can be contagious even in the throat and saliva before the infection reaches the upper respiratory tract. This shows that taking a swab from the nose at the early stage of infection will not be enough to detect the virus.
According to a small-scale study conducted in the USA, PCR tests of throat swabs taken from 29 people infected with Omicron detected the virus on average three days before it was positive in antigen tests from nasal swab.
Rapid tests are often less sensitive than PCR tests processed in the laboratory. This means that home tests are more likely to be “false negatives”. However, if the result is positive, it is almost certain that you have caught Covid-19. In the last wave of the epidemic that came with Omicron, the increasing demand for PCR tests increases the pressure on laboratories, while antigen tests play an important role in efforts to contain the pandemic.
Should a swab be taken from the throat before the nose?
According to the results of recent studies, some experts in the USA recommend that those who will use antigen testing take a throat swab before the nose swab.
All antigen tests approved for emergency use by the US Food and Drug Administration (FDA) were produced as nasal swabs. This raises concerns that home antigen tests may not be safe to use to take a throat swab. Users are advised to follow the test manufacturers’ instructions.
However, health officials in Israel have recommended that those doing rapid home antigen testing for Covid-19 take swabs from their throats as well as their noses, although this is not in accordance with the manufacturer’s instructions for use.
Some other countries, including the UK, have developed antigen tests so that they can be sampled from both the nose and throat.
The German Ministry of Health also announced that they will examine how safe rapid antigen tests are in detecting the Omicron variant and will publish a list of the most effective tests.