Credit: Katrina Williams

The tests you don’t need to study for

By Lucy Dunn

Health scares and pharmacy trips: what do we test for, and how does it work?

“Getting tested” is a hot topic just now, given that none of us can escape Covid-19 and the constant threat of isolation, but what other tests should we be aware of, why are they relevant to us, and how can we get them?

Covid: PCR and LFTs

Acronyms that were never previously in our vocabulary have become household names, but what do they do, and what’s the difference between them?

PCRs, or polymerase chain reactions, are tests that look for viral RNA, to then amplify it into DNA, replicate it, as per the polymerase chain reaction technique, to test for the presence of SARS-CoV-2. These are the tests that you would get in the UK if you booked a Covid test via the government website, and they are considered the most reliable testing method. At first, test centre workers would swab you themselves, however generally now, when you drive or walk into the centres, you are able to test yourself, by swabbing your tonsils (the two lumpy bean-shaped structures present at either side of your throat, on each side of your uvula) and your nose, inserting the swab pretty high to be as effective as possible. Results will usually get back to you within 24 hours.

The method for lateral flow testing (LFTs) is very similar, but they work differently. LFTs use “immunoassay” technology to detect specific antigens (bugs) in a sample. When the sample is dropped onto the device, it will flow along the test strip. It will pass along pads layered with antibodies, substances that recognise and bind to specific antigens, and binding agents. If the antigens are present in the sample, they will bind at a certain point, forming a coloured line on the test. However, whilst used more regularly in daily life to indicate being Covid-free, lateral flow tests are actually less reliable than PCRs, as they cannot detect low levels of Covid-19 in a sample.

“If the antigens are present in the sample, they will bind at a certain point, forming a coloured line on the test.”

Pregnancy tests: hCG

Pregnancy tests work similarly to LFTs, only instead of measuring levels of SARS-CoV-2, they detect human chorionic gonadotropin (hCG) which is a hormone produced by the placenta (the route of nourishment the baby receives from the mother prior to birth). The sample required for the test is urine, which will contain hCG if the user is pregnant. Like with LFTs, there is a pad that contains antibodies that will bind to hCG if it’s there. Then, the sample will continue to move along the test strip, until it reaches the “test line” that will appear if certain enzymes are present: the enzymes involved in the binding of hCG to its antibodies. With both LFTs and pregnancy tests that are negative, only one line – the control – will show up as a “control” to ensure the test has actually functioned. The “test” line is the second one, which is why two lines on both a Covid LFT and a pregnancy test indicate a positive result. 

Sexually transmitted diseases:

There are a number of STIs – or sexually transmitted infections (the term synonymous with sexually transmitted diseases, or STDs) – that you can contract. What are the big ones, how can you contract them, and what’s the cure?

Chlamydia: One of the most common STIs, chlamydia is contracted when your “mucous membranes” come into contact with the bacteria. It can be transmitted during oral, vaginal, or anal sex, however, it is more common to experience genital chlamydia than an infection in the throat. Often no symptoms are seen – in 90% of women and 70% of men – however bleeding, discharge and pain may be observed. Chlamydia is easily treatable with a week-long course of antibiotics; without treatment, complications can lead to testicular inflammation in men, and infertility in women. The infection is preventable by condom use. 

“Often no symptoms are seen – in 90% of women and 70% of men…”

Gonorrhoea: Sometimes referred to as “the clap”, gonorrhoea is another bacterial infection that can be spread through oral, vaginal, or anal sex. Again, sometimes you can be infected with gonorrhoea and show no symptoms (more common if you’re a woman). Treated with a single antibiotic injection and a tablet, symptoms will likely go within a few days. Long-term effects are similar to the above, and can sometimes lead to affecting male fertility, too. On very rare occasions, the bacteria can get into the blood and cause sepsis, which can be fatal. Prevention is key: use condoms, and don’t share sex toys.

“Sometimes referred to as “the clap”, gonorrhoea is another bacterial infection…”

Syphilis: often presenting with small, painless ulcers around the genitals or mouth – called chancres – syphilis may also cause no symptoms. It is a bacterial infection that, if left untreated, can spread to, and damage, the heart and brain. Getting tested is vital, and unlike chlamydia and gonorrhoea swabs, it requires a blood test. Treatment is in the form of an antibiotic injection, and it is important to avoid any sexual activity with anyone else until at least 2 weeks afterwards.

HIV: Human immunodeficiency virus damages your immune system, causing your body to become less able to fend off any infections it may encounter. This is a viral infection, rather than being bacterial, and so requires a different form of treatment. Symptoms are flu-like and usually experienced 2-6 weeks after you get infected. If you become HIV-positive you can never get completely rid of the virus, but you can reduce your viral load to become undetectable with treatment. You will require a blood test, which may need to be repeated to confirm the result, and if positive you will get referred to a specialist HIV clinic for more information. Treatment is with antiretroviral therapy which will help to stop the virus from amplifying itself. Prevention is in the form of condom use, PrEP (a medicine you can take before possible exposure) and PEP (a medicine you take within 72 hours of exposure to HIV). 

It’s never nice thinking that you may have picked up a bug or infection, and when symptoms are so vague, it can be hard to know if you’re being incredibly intuitive, or just melodramatic. Most test kits are available freely via the NHS, however you can also buy tests online (e.g. the Superdrug online pharmacy) or at your local chemist. If you’re looking for more information on any of the above, please go to the NHS website, or to NHS Inform. And, with everything, remember: stay informed, stay vigilant, and stay safe!


Share this story

Follow us online

Notify of

Inline Feedbacks
View all comments