Covid-19: where does testing help?

Byline: Fawzia Rasheed , El-Nasir Lalani and Gijs Walraven

CALLS for 'testing' are understandable. Many want to know their status and realise that 'testing' cannot only slow transmission but also help regain some normality if used to guide 'reopening'. And yet, there is widespread confusion around what tests are available and their benefits.

Just because one can get a test, it does not mean one should invariably go for it.

This is an attempt to answer questions we are asked by people outside and even within the health sector as this is a specialised area and the literature is not easy to navigate.

Some facts help. First, Covid-19 symptoms mostly show around five to six days after infection, but can take as long as two weeks. Second, those carrying the virus (SARS-CoV-2) can infect others before and after symptoms show.

And lastly, antibodies are produced quite late after infection --- from the second week onwards and well after the first symptoms appear.

There are different ways to assume someone was or is infected: using clinical symptoms (cough, fever etc), antibody tests (which detect the human response to infection) or virus tests (which detect actual components of the virus circulating in the body).

Using clinical symptoms is by far the most widespread method used to identify Covid-19; this approach does not prove but assumes a diagnosis based on symptoms typical for this disease.

The drawbacks of this approach include inability to detect infection among people with mild or few symptoms. This could happen in as many as 80 per cent of the cases. That said, people with no or few symptoms are unlikely to consider getting a test in any case.

Another problem with detecting the virus through clinical symptoms is that many Covid-19-related symptoms are similar to those of other infections, which means people could be diagnosed as having Covid-19 when in fact they do not. The benefits, however, include that it's free - anyone can use the checklist of questions recommended to identify Covid-19 infections on themselves or others.

A further benefit is that those who use this method learn how to suspect infection in themselves as well as others and get advice on steps to take; ranging from self-isolation at home if symptoms are mild, or contact a doctor if symptoms are more serious or coupled with additional health problems.

When people are helped to diagnose themselves and take appropriate action, this helps the individual and health workers too.

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