Over the past month or two, many northern hemisphere countries including the US and the UK have seen a large wave of respiratory viral infections. These include RSV (respiratory syncytial virus), flu 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 surge in hospital admissions during winter, putting the health service under further stress.
This had led some to question whether COVID damages our immune systems, 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 out” on common childhood infections during the height of the pandemic, and that this has left them more vulnerable to these infections now owing to an “immunity debt”. But how credible are these explanations?
The human immune system has evolved to deal with a host of different infections. It has a variety of weapons it can deploy which work together not only to eradicate infectious agents, but also to remember them for a more rapid and tailored response upon any subsequent encounter.
Likewise, many infectious agents have developed tricks to try to evade our immune system. For example, a parasite called Schistosoma mansoni disguises itself to avoid the immune system detecting it.
SARS-CoV-2, the virus that causes COVID-19, similarly has tricks up its sleeve. Like many other viruses, it’s been shown to evade host immunity, particularly newer variants. Recent studies showed it can interfere with immune cells’ ability to detect it within cells. This is concerning, but it’s not clear that such changes impact immunity to other infections.
Short-lived changes in a person’s immune defences are normal when they’ve been exposed to an infection. Several studies have now shown that, in response to SARS-CoV-2, specialised white blood cells called lymphocytes grow in number. These lymphocytes also display changes in their features typical of cell activation, such as changes in surface proteins.
Such changes may sound dramatic to the non-expert if taken out of context (called “ascertainment bias”). But they’re normal and merely indicate that the immune system is working as it should. Research has confirmed that, for most people, the immune system regains balance following recovery.
Some exceptions
SARS-CoV-2, like many viruses, doesn’t affect everyone equally. We’ve known for some time that certain groups, including older people and those with underlying health complications such as diabetes or obesity, can be more susceptible to severe disease when they contract COVID.
This vulnerability is associated with an irregular immune response to SARS-CoV-2 that results in inflammation. Here we see, for instance, reduced numbers of lymphocytes and changes to immune cells known as phagocytes.
Still, for most of these vulnerable people, the immune system returns to normal over the next two to four months. However, a small subset of patients, particularly those who had severe COVID or have underlying medical issues, retain some changes beyond six months after infection.
The significance of these findings isn’t clear, and longer-term studies considering the impact of underlying health conditions on immune function will be needed. But for most people, there’s no evidence to suggest immune damage following a COVID infection.
For some people with underlying health conditions, immune changes appear to last longer. pikselstock/Shutterstock
So far, no data points to immune deficiency in long COVID patients. But an overactive immune response can actually cause harm, and the immune cell changes seen in long COVID patients seem consistent with a vigorous immune response. This may explain the variety of post-infection consequences and symptoms that people with long COVID face.
Immunity debt
The “immunity debt” hypothesis suggests the immune system is like a muscle requiring near-constant exposure to infectious agents to keep it functioning. So, the argument goes, a lack of exposure due to lockdowns damaged immune development, especially in children, by making our immune systems “forget” earlier knowledge. This supposedly left them more vulnerable to infections when social mixing returned to normal.
Though this idea has gained traction, there’s no immunological evidence to support it. It’s not true to say we require a constant background of infection for our immune system to work. Our immune systems are immensely robust and powerful. For example, immune memory to the 1918 influenza pandemic was still evident after 90 years.
It’s also not strictly true to say children weren’t exposed to viruses during the early pandemic. Lockdowns didn’t commence until after waves of the usual winter respiratory infections in 2019/2020, and schools in the UK reopened in autumn 2020 with variable preventive measures, so children were still exposed to infections, including COVID-19.
The cold-causing viruses didn’t completely vanish by any means. For example, there was a significant RSV outbreak in the UK in 2021.
Nonetheless, lockdowns and other protective measures probably did reduce exposure to viruses, and for some children this shifted when and at what age they were first exposed to viruses such as RSV. This, taken alongside a high background of COVID, and relatively poor COVID and flu vaccine uptake, could all be making this season particularly bad. However, a change in the timing of when people are exposed leading to a surge of infections doesn’t necessarily mean that individual immunity has been damaged.
EASTMOJO PREMIUM
Help sustain honest journalism.
Our knowledge of the immune response to COVID is rapidly expanding. The most consistent findings show how well vaccines are protecting us from the very worst effects of SARS-CoV-2 and that, post-vaccination, our immune system is working exactly as it should.
However, findings of altered immune signatures in some recovered patients and those with long COVID require further investigation.
WASHINGTON (AP) — Americans can once again order COVID-19 tests, without being charged, sent straight to their homes.
The U.S. government reopened the program on Thursday, allowing any household to order up to four at-home COVID nasal swab kits through the website, covidtests.gov. The tests will begin shipping, via the United States Postal Service, as soon as next week.
The website has been reopened on the heels of a summer COVID-19 virus wave and heading into the fall and winter respiratory virus season, with health officials urging Americans to get an updated COVID-19 booster and their yearly flu shot.
“Before you visit with your family and friends this holiday season, take a quick test and help keep them safe from COVID-19,” U.S. Health and Human Services Assistant Secretary for Preparedness and Response Dawn O’Connell said in a statement.
U.S. regulators approved an updated COVID-19 vaccine that is designed to combat the recent virus strains and, they hope, forthcoming winter ones, too. Vaccine uptake is waning, however. Most Americans have some immunity from prior infections or vaccinations, but under a quarter of U.S. adults took last fall’s COVID-19 shot.
Using the swab, people can detect current virus strains ahead of the fall and winter respiratory virus season and the holidays. Over-the-counter COVID-19 at-home tests typically cost around $11, as of last year. Insurers are no longer required to cover the cost of the tests.
Before using any existing at-home COVID-19 tests, you should check the expiration date. Many of the tests have been given an extended expiration from the date listed on the box. You can check on the Food and Drug Administration’s website to see if that’s the case for any of your remaining tests at home.
Since COVID-19 first began its spread in 2020, U.S. taxpayers have poured billions of dollars into developing and purchasing COVID-19 tests as well as vaccines. The Biden administration has given out 1.8 billion COVID-19 tests, including half distributed to households by mail. It’s unclear how many tests the government still has on hand.
WASHINGTON (AP) — Americans can once again order free COVID-19 tests sent straight to their homes.
The U.S. government reopened the program on Thursday, allowing any household to order up to four at-home COVID nasal swab kits through the website, covidtests.gov. The tests will begin shipping, via the United States Postal Service, as soon as next week.
The website has been reopened on the heels of a summer COVID-19 virus wave and heading into the fall and winter respiratory virus season, with health officials urging Americans to get an updated COVID-19 booster and their yearly flu shot.
U.S. regulators approved an updated COVID-19 vaccine that is designed to combat the recent virus strains and, they hope, forthcoming winter ones, too. Vaccine uptake is waning, however. Most Americans have some immunity from prior infections or vaccinations, but under a quarter of U.S. adults took last fall’s COVID-19 shot.
Using the swab, people can detect current virus strains ahead of the fall and winter respiratory virus season and the holidays. Over-the-counter COVID-19 at-home tests typically cost around $11, as of last year. Insurers are no longer required to cover the cost of the tests.
Since COVID-19 first began its spread in 2020, U.S. taxpayers have poured billions of dollars into developing and purchasing COVID-19 tests as well as vaccines. The Biden administration has given out 1.8 billion COVID-19 tests, including half distributed to households by mail. It’s unclear how many tests the government still has on hand.
TORONTO – A coalition of disability rights groups says it is launching a Charter challenge against a part of Canada’s law on medical assistance in dying.
The group, which also includes two individual plaintiffs, argues that what’s known as track two of the MAID law has resulted in premature deaths.
Under the law, patients whose natural deaths are not reasonably foreseeable but whose condition leads to intolerable suffering can apply for a track-two assisted death.
The coalition says track two of the MAID law has had a direct effect on the lives of people with disabilities and argues medically assisted death should only be available to those whose natural death is reasonably foreseeable.
The executive vice-president of Inclusion Canada – which is part of the coalition – says there has been an alarming trend where people with disabilities are seeking assisted death due to social deprivation, poverty and a lack of essential supports.
Krista Carr says those individuals should instead be supported in order to live better lives.
This report by The Canadian Press was first published Sept. 26, 2024.
