Misconceptions about meaning of antigen results widespread, report finds

Almost half think person with Covid symptoms does not have to isolate if rapid test result negative

A Covid-19 rapid antigen test. Photograph: Joel Carrett/EPA

A Covid-19 rapid antigen test. Photograph: Joel Carrett/EPA

 

Widespread misconceptions exist about Covid-19 antigen testing, according to a new report, with almost half of us thinking a person with symptoms doesn’t have to self-isolate if there is a negative result.

Twelve per cent say they do not know how to interpret a negative antigen test and another 4 per cent say it is fine to socialise, even with symptoms.

This baseline level of public understanding presents a “clear set of communications challenges,” according to the interim report of the rapid testing expert advisory group.

The Government earlier this week gave the go-ahead for the use of antigen testing for asymptomatic close contacts, and their wide use for large events. Up to now, the National Public Health Emergency Team has resisted the wider use of antigen testing, arguing it was inferior to the system of PCR testing already in place.

The report says rapid antigen tests (RADT) are an additional tool and not a substitute for existing public health measures. PCR testing remains the “gold standard” for diagnosing Covid-19 infections.

But antigen tests can reliably detect those most likely to be infectious and the speed with which the result is obtained enables “rapid intervention” to prevent onward transmission of the virus. Although they do not identify all cases, they are cheap and can be deployed at scale.

The results of antigen tests are available within minutes, whereas it takes about a day for the result of more expensive PCR testing to be provided.

Less than half of the population knew an antigen test was “less good” at detecting the virus than a PCR test, according to a survey carried out for the report.

Some 39 per cent of people though that where a person with symptoms took a rapid test and got a negative result, s/he had no need to self-isolate.

“Overall, the results suggest widespread misconceptions in Ireland about the sensitivity of RADT, how they are of benefit, and the implications of test results.”

“In a landscape of continual change as demonstrated by the unpredictability of this pandemic, it is possible rapid antigen testing may play an important part of future testing programmes.”

Antigen testing may have a role within specific settings as a complementary public health intervention to existing infection prevention and control measures, the report states.

There may be benefits to deploying it in specific settings “depending on the incidence of Covid-19 in the country”.

“It is important that the benefits and limitations of all tests are communicated to the public. It should be noted that rapid antigen detection tests should not be used to support behavioural changes that are contrary to public health recommendations.”

The expert advisory group, chaired by Prof Mary Horgan, was appointed by the Minister for Health last July.