Living through a heatwave with suspected Covid symptoms?
Surely the sweltering temperatures are enough to contend with, without having a cough, fever, scratchy throat or loss of taste on top.
But with almost 175,000 new coronavirus cases reported in the past week in the UK alone, there will be some people in Britain living through that very scenario.
Households with a stash of lateral flow tests left can normally self-diagnose whether they have coronavirus or not in just a few short minutes.
However, experts have warned that the record-breaking heat being experienced in parts of the UK could change the effectiveness of the tests.
Do Covid tests work in a heatwave?
Heat above 30C can impact on the effectiveness of a lateral flow test, meaning your result may not be accurate if taken during the current warm conditions.
Most of England and Wales, along with spots in Scotland, are set to exceed that maximum temperature, with highs of 40-plus degrees Celsius expected in London on Tuesday (July 19).
The US Food and Drug Administration (FDA) - the Stateside equivalent to the UK regulator, the Medicines and Healthcare products Regulatory Agency (MHRA) - said “test performance may be impacted if the test is used in a hotter than expected environment”.
It notes how stated performance in the information leaflet of swab packs “generally assumes the test is being performed in an environment that is between 15-30⁰C”.
It might mean that those living in the hottest parts of the country might need to take action before going through the rigmarole of a coronavirus test.
Should you keep your Covid test in the fridge?
A fridge would be too cold for a Covid-19 lateral flow test.
Giulia Guerrini, lead pharmacist at digital pharmacy Medino, said: “You shouldn’t refrigerate them, because storing your lateral flow kits at very cold temperatures can also reduce their reliability.”
The MHRA guidance for using at-home tests also states: "Remember, store the test kit at room temperature – not in direct sunlight and not in a fridge or freezer."
So while there is such a thing as it being too hot for Covid-19 tests to function properly, there is also a case of being too cold as well.
What to do with your Covid test if it is warm
The FDA’s recommendation is to keep a test at room temperature - around 18C in the UK - for at least two hours before using its apparatus.
On the US regulators website, it states: “Once the package is at room temperature, you may open it and perform the test according to the authorised instructions for use.
“As long as the test line(s) appear as described in the instructions, you can be confident that the test is performing as it should.
“If the line(s) do not appear in the correct location(s) and within the correct time as shown in the test instructions when you perform the test, then the results may not be accurate, and a new test is needed to get an accurate result.”
If a pack has had “long exposure to high temperatures”, then the FDA recommends binning the test entirely and sourcing a new set.
Where should you store your Covid tests in the heat?
Medino pharmacist Ms Guerrini said a specified cupboard or draw that does not get much sunlight is the best place to keep lateral flows.
“The easiest way to ensure your lateral flow kits stay in the best possible condition, no matter the weather, is to store them in a cool, dry place, out of the sun,” she said.
“For example, a medicine cabinet, kitchen cupboard or drawer will all protect the integrity of the tests, even in a heatwave.”
Why must Covid tests stay within 15-30C?
“Storing the test at higher temperatures can irreversibly damage the swab, as well as the chemicals used in the test,” Ms Guerrini explained.
“This means that when the time comes to take a test, your results will not be entirely reliable as the chemical make-up of the test will be altered.”
