COVID-19: The science

Coronavirus has stormed the world, drastically altering our day to day lives. For the majority of people that become infected, symptoms are unpleasant but generally not life threatening. Unfortunately, a small but significant proportion of those that become infected require care in a hospital, often in Intensive Care Units (ICU).

This article, written by Hometest's Chief Medical Officer Dr Ian Mann, addresses some of the most common questions we hear about the virus and how it can be controlled. If you’re interested in learning more about the science behind testing, take a look at our article COVID-19 Testing: How it works (and why we need it).

What is COVID-19?

COVID-19, commonly referred to as Coronavirus or just Covid, is a highly contagious disease. The underlying virus, SARS-CoV-2, is actually just one of a group of related RNA viruses which are collectively called “Coronaviruses”—although most have a much less severe effect, including some instances of the common cold.

Where did COVID-19 come from?

COVID-19 was first identified in December 2019—which is where the '19' part of the name comes from. There is some controversy over its origins, but however it got out, it was originally an animal virus which changed (mutated) and became able to cause disease in humans. Historically, there have been outbreaks of infections from many viruses that originated in animals: avian flu from birds, swine flu from pigs, and Severe Acute Respiratory Syndrome (SARS-Cov-1) from bats.

What makes COVID-19 harder to handle than other viruses like Flu?

The COVID-19 outbreak has been particularly difficult because of something called the 'incubation period'. This is the number of days between the time that an individual becomes infected and when they begin to see symptoms. For COVID-19 this can be as long as 10 days. During this period an infected person can go about their daily activities feeling perfectly well, unaware that they are spreading the infection to others.

The virus is spread in tiny droplets when the incubating/infected individual coughs, sneezes, talks or even just breathes normally, particularly in confined spaces with bad ventilation. These droplets can remain suspended in air for a considerable time, increasing the potential they get inhaled by a healthy person—who then catches the virus themselves. 

What can we do to take back control of the epidemic?

There are two critical tools that can be used to keep the COVID-19 epidemic under control: vaccination and testing. Fortunately, the UK is a world leader when it comes to vaccination, with a highly efficient programme which has got through most of the adult population in a very short space of time. 

The other tool is testing. You might wonder why this is necessary, especially if everyone has been vaccinated.

The first reason is that, while vaccinations have been proven to be extremely effective at both stopping people getting Coronavirus and limiting how ill those who get it become, they aren’t perfect. There have been a few high-profile cases of people getting COVID-19 even after being vaccinated (including the BBC’s Andrew Marr), so while infection rates remain high it’s important we are all cautious and take a test if we feel unwell.

The second reason is that the vaccinations protect people against the virus we knew at the start of the Covid crisis. As time has gone on, the virus has slowly changed, with some of these mutations resulting in different and new characteristics—which we have been able to quickly detect and monitor thanks to testing and genomic sequencing. The Delta variant is the most recent major mutation, but before that we also had the Kent variant (now called “Alpha”), which caused huge disruption when it emerged just before Christmas in 2020. 

Thankfully, vaccines do offer a level of protection against most of the new variants that have emerged—but health authorities are understandably keen to catch any new variants early and track their progress, to make sure this remains the case. If it doesn’t, it might be that we need to have boosters to cover new strains more effectively. This is what happens with flu, and why vulnerable people need to have a new flu vaccine each winter.

As a result, it looks likely that testing will remain a part of our lives for some time. This is particularly important for international travel, especially if people are visiting countries with low vaccination rates or where new variants might have emerged. 

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