Medical

# Sensitivity and Specificity

## The sensitivity of SARS-CoV-2 rapid tests explained:

The sensitivity of SARS-CoV-2 rapid tests describes the likelihood of a positive test result that is correctly identified as positive.

Sensitivity therefore tells you how likely you are to get a positive test result if you are actually positive.

Example of use: The sensitivity of a rapid test is approximately 96.5%. This means:

• at 96.5% you get a positive test result and are also really positive.
• to 3.5% you get a positive test result but are actually negative (false-positive result).

This is the reason why positive test results should always be checked with a more accurate PCR test in the laboratory.

## The specificity of SARS-CoV-2 rapid tests simply explained.

The specificity of tests describes the probability that a negative test result is actually negative. So specificity says: how likely you are to get a negative test result and actually be negative.

Example of use: The specificity of a rapid antigen test is approximately 99.7%. This means:

• 99.7% of the test results are negative and really negative.
• to 0.3% you then get a negative test result, but are actually positive (false negative result). As you can see, the specificity of a rapid antigen test is very good, which is why retesting is not usually recommended here.

## The mean value as test accuracy

The mean value of sensitivity and specificity is often summarised as test accuracy. It is important to actually look at both values when choosing a particular test.

Example of use: If the sensitivity of an antigen test is 96.5% and the specificity is 99.7%, the test accuracy is 98.1%.

• 99.7% of the test results are negative and really negative.
• to 0.3% you then get a negative test result, but are actually positive (false negative result). As you can see, the specificity of a rapid antigen test is very good, which is why retesting is not usually recommended here.

## The mean value as test accuracy

The mean value of sensitivity and specificity is often summarised as test accuracy. It is important to actually look at both values when choosing a particular test.

Example of use: If the sensitivity of an antigen test is 96.5% and the specificity is 99.7%, the test accuracy is 98.1%.

• 99.7% of the test results are negative and really negative.
• to 0.3% you then get a negative test result, but are actually positive (false negative result). As you can see, the specificity of a rapid antigen test is very good, which is why retesting is not usually recommended here.

## The mean value as test accuracy

The mean value of sensitivity and specificity is often summarised as test accuracy. It is important to actually look at both values when choosing a particular test.

Example of use: If the sensitivity of an antigen test is 96.5% and the specificity is 99.7%, the test accuracy is 98.1%.

• 99.7% of the test results are negative and really negative.
• to 0.3% you then get a negative test result, but are actually positive (false negative result). As you can see, the specificity of a rapid antigen test is very good, which is why retesting is not usually recommended here.

## The mean value as test accuracy

The mean value of sensitivity and specificity is often summarised as test accuracy. It is important to actually look at both values when choosing a particular test.

Example of use: If the sensitivity of an antigen test is 96.5% and the specificity is 99.7%, the test accuracy is 98.1%.

• 99.7% of the test results are negative and really negative.
• to 0.3% you then get a negative test result, but are actually positive (false negative result). As you can see, the specificity of a rapid antigen test is very good, which is why retesting is not usually recommended here.

## The mean value as test accuracy

The mean value of sensitivity and specificity is often summarised as test accuracy. It is important to actually look at both values when choosing a particular test.

Example of use: If the sensitivity of an antigen test is 96.5% and the specificity is 99.7%, the test accuracy is 98.1%.

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