The short answer is yes — you can get COVID-19 twice — but it’s a little more complicated than that. Here’s all you need to know.
You’ve had all your vaccines, you’ve followed all the social distancing rules, but you’ve still wound up contracting COVID-19. Frustrating isn’t it? Don’t worry, you’re not alone. Over 1.5 million Australians have now contracted Covid, despite the fact that 93% of people aged 16 and over are now fully vaccinated.
Whilst getting the vaccine helps your immune system to fight off the infection, it doesn’t stop you from contracting the virus in the first place. Nor does it stop you from getting Covid again.
But if you’ve just had the virus, that’s not to say you’ll get it again immediately after you’ve recovered. When a person catches the coronavirus, the immune system generates a response that helps them fight off the virus if they are exposed to it again.
It works very much in the same way the vaccine does — it exposes you to the virus, your immune system then stimulates an immune response that produces protective antibodies so your body is equipped to fight off the infection if and when you contract it.
Like the vaccine, exposure to the virus essentially teaches your immune system to fight the actual virus if it encounters it.
So if get Covid once, that means I have natural immunity?
Yes, but the problem is, experts don’t know how long this immune response lasts, and it also appears to vary between different people.
Immunity is strongest immediately following an illness — this is because your immune system has the virus fresh in its memory, so it knows what to look out for to fight against it.
The immune system is a complex network of cells, chemicals, tissues and organs that constantly protects your body against pathogens, viruses, toxins and bacteria, that can potentially invade the body and make you sick.
It identifies these ‘invading pathogens’ by triggering an immune response, with the goal of restoring your body’s immunity to a normal healthy function. Once the immune system has destroyed the invader, it remembers it. It actually keeps a record of every microbiome it has ever defeated in types of white blood cells (B- and T-lymphocytes) known as memory cells.
This means recognises the microbiome as soon as it enters your body, and then destroys it before it makes you sick.
Immunity is, therefore, most powerful immediately following an illness, when the cellular memory of the infection and neutralising antibodies are at their strongest.
But because these memory cells only remember the exact strain of infection, the immune system won’t necessarily recognise any new strains of the illness. You’re only immune to the strain of Covid you’ve been exposed to, and for a limited time period.
It’s all down to the neutralising antibodies — they trigger the immune system’s frontline arsenal during infection and vaccination. Their job is to shield cells that usually target the pathogen from being infected. The neutralising antibodies your body produces define how affectively your body fights off the illness.
In a recent study conducted by the University of Sydney, Kids Research, Sydney Children’s Hospitals Network, the Kirby Institute at UNSW Sydney, Australian Red Cross Lifeblood, St Vincent’s Hospital and NSW Health Pathology, as well as other local and international collaborators, scientists researched how our immune system responds to COVID-19.
The study suggests that while your body does produce a natural immune response following infection, vaccinations are much more effective against newer strains of the virus. Mutations of the virus essentially compromise a person’s immunity, which means there’s every chance you can get Covid again, because your immune response is only equipped to recognise that particular variant.
In a statement, Co-senior author Associate Professor Stuart Turville of the Kirby Institute said: “What this work has shown us is that current observations about vaccines show they offer a much broader protection against COVID-19 and its variants than the body’s natural immune response following infection, which is usually only protective against the variant of the virus that the person was infected with. We, therefore, should not rely on the body’s natural immune response to control this pandemic, but rather the broadly protective vaccines that are available.”
So I can still get Covid even though I’ve had all my vaccines?
Technically yes. The vaccines are designed to protect people against severe illness and disease as a result of COVID-19, but it won’t necessarily protect you from contracting it. It just means that your immune system is better equipped to fight off the infection when you do get it.
It also takes time for your body to build up an immune response following a vaccination. Most people need two doses for strong protection against the virus that causes COVID-19.
The Omicron variant for example, which is now the most dominant strain of Covid in Australia, has many mutations to the spike protein produced by the vaccine, which means lots of people are getting reinfected with this newer strain.
A report by Imperial College London suggests that Omicron is more than five times more likely to cause reinfection that the Delta variant. So basically, anyone who caught COVID-19 linked to one strain could be reinfected with another strain.
What it does mean, however, is that even if you do contract Covid again, if you’re fully vaccinated, you’re less likely to develop serious illness than those who are unvaccinated and get COVID-19. Even when fully vaccinated people develop symptoms, they tend to be less severe than in unvaccinated people. This means when they get Covid, they are much less likely to be hospitalised or die than people who haven’t had a vaccine.
Whether you’ve had COVID-19 already or not, the safest way to protect yourself from severe illness is to make sure you’ve had your two vaccines, and your booster jab, if you’ve been offered one. You should also continue to wear masks in enclosed spaces and keep your hands clean and sanitised regularly to help reduce your risk.
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