Is COVID really damaging your immune system and making you more susceptible to infections?

In the past two months, many countries in the northern hemisphere, including the United States and the United Kingdom, have experienced a large wave of respiratory viral infections. These include RSV (respiratory syncytial virus), influenza and COVID in all ages, as well as bacterial infections such as strep A in children.

Sometimes these infections can be very serious. The UK has seen a huge spike in hospital admissions over the winter, which has put health services under pressure.

This has led some to wonder if covid damages our immune system, leaving those who have been infected more vulnerable to other infectious diseases like the flu.

Another idea put forward to explain the surge in respiratory viruses is that children “missed” common childhood infections at the height of the pandemic, and this has made them more vulnerable to these infections now due to a “debt of ‘immunity’. But how credible are these explanations?

COVID and our immune system
SARS-CoV-2 has been shown to evade host immunity, especially newer variants. (Source: Pixabay)
The human immune system has evolved to deal with a multitude of different infections. He has a variety of weapons that he can deploy that work together to not only eradicate infectious agents, but also to remember them for a faster and more suitable response to any subsequent encounters.

Similarly, many infectious agents have developed tricks to try to escape our immune system. For example, a parasite called Schistosoma mansoni disguises itself to prevent the immune system from detecting it.

SARS-CoV-2, the virus that causes COVID-19, also has tricks up its sleeve. Like many other viruses, it has been shown to evade host immunity, especially newer variants. Recent studies have shown that it can interfere with the ability of immune cells to detect it in cells. This is concerning, but it is unclear whether such changes impact immunity against other infections.

Short-term changes in a person’s immune defenses are normal when they have been exposed to an infection. Several studies have now shown that in response to SARS-CoV-2, white blood cells called lymphocytes multiply. These lymphocytes also show changes in their typical characteristics of cell activation, such as changes in surface proteins.

Such changes can seem dramatic to the non-expert if taken out of context (called “evaluation bias”). But they are normal and just indicate that the immune system is working as it should. Research has confirmed that, for most people, the immune system regains its balance after recovery.

Some exceptions

SARS-CoV-2, like many viruses, does not affect everyone equally. We have known for some time that certain groups, including the elderly and those with underlying health complications such as Diabetes or obesity, may be more susceptible to serious illness when they contract COVID.

This vulnerability is associated with an irregular immune response to SARS-CoV-2 that leads to inflammation. Here we see, for example, a reduced number of lymphocytes and changes in immune cells called phagocytes.

Yet for most of these vulnerable people, the immune system returns to normal within the next two to four months. However, a small subset of patients, particularly those who have had severe COVID or have underlying medical conditions, retain some changes beyond six months after infection.

The significance of these findings is unclear, and longer-term studies taking into account the impact of underlying health conditions on immune function will be needed. But for most people, there is no evidence to suggest immune damage as a result of COVID infection.

What about long COVID?

Emerging evidence suggests that the most marked and persistent differences in immune cells after COVID infection occur in people who have developed long COVID.

So far, there is no data indicating immune deficiency in patients with long-term COVID. But an overactive immune response can actually cause harm, and the immune cell changes seen in longtime COVID patients appear consistent with a vigorous immune response. This may explain the variety of post-infection consequences and symptoms that people with long-term COVID face.

Immunity debt
COVID-19 virus A lack of exposure due to lockdowns harms immune development, especially in children, by causing our immune system to “forget” prior knowledge. (Source: Pexels)
The “immune debt” hypothesis suggests that the immune system is like a muscle requiring near-constant exposure to infectious agents to keep functioning. So, the argument goes, a lack of exposure due to lockdowns has damaged immune development, especially in children, by causing our immune systems to “forget” prior knowledge. This would have made them more vulnerable to infections when social mixing returned to normal.

Although this idea has gained traction, there is no immunological evidence to support it. It is not true to say that we need a constant background of infection for our immune system to work. Our immune system is extremely robust and powerful. For example, the immune memory of 1918 flu the pandemic was still evident after 90 years.

Nor is it strictly true to say that children were not exposed to viruses at the start of the pandemic. Lockdowns only started after the usual waves of winter respiratory infections in 2019/2020, and schools across the UK reopened in autumn 2020 with varying preventative measures, so children were still at risk infections, including COVID-19.

The viruses responsible for the common cold have by no means completely disappeared. For example, there was a major RSV outbreak in the UK in 2021.

However, blockages and other protective measures likely reduced exposure to viruses, and for some children this changed when and at what age they were first exposed to viruses such as RSV. This, combined with a high COVID background and relatively low COVID and flu vaccine uptake, could all make this season particularly bad.

However, a change in when people are exposed, leading to an upsurge in infections, does not necessarily mean that individual immunity has been damaged.

Our knowledge of the immune response to COVID is expanding rapidly. The most consistent results show how well vaccines protect us from the worst effects of SARS-CoV-2 and that, after vaccination, our immune system works exactly as it should.

However, findings of altered immune signatures in some recovered patients and those with long COVID require further investigation.

📣 For more lifestyle news, follow us on Instagram | Twitter | Facebook and don’t miss the latest updates!

Is COVID really damaging your immune system and making you more susceptible to infections?

Leave a Reply

Your email address will not be published.

Scroll to top