• Home
  • Health & Wellness
  • Disclaimer
    • Terms of Use
    • Privacy Policy
    • DMCA Notice
Podcast
  • Home
  • Health & Wellness
  • Disclaimer
    • Terms of Use
    • Privacy Policy
    • DMCA Notice
24/7 Health News
No Result
View All Result
Home Article

COVID reinfections: are they milder and do they strengthen immunity?

February 11, 2022
in Article
0
COVID reinfections: are they milder and do they strengthen immunity?
file 20220211 19 vof5q

illpaxphotomatic/Shutterstock

We’ve known since early on in the pandemic that COVID reinfections could occur. One of the first reinfections reported was in a 33-year-old man from Hong Kong. His initial infection was diagnosed on March 26 2020, with his second infection, with a genetically distinct virus, being diagnosed 142 days later.

Since then reports of reinfection have become common, especially since the emergence of the omicron variant. Early research from South Africa (still in preprint, so awaiting review by other scientists) suggests that the risk of reinfection increased quickly and substantially after the variant arrived.

So why are reinfections increasing? The simple answer is because our immunity is often no longer sufficient to prevent an infection. This can be due to the appearance of a new viral variant like omicron that, because of mutations to its form, is less recognisable to the immune system, meaning the virus bypasses prior immunity. Or it can be because immunity has waned since we were last infected or vaccinated. We know that this is a particular issue with COVID immunity – hence the need for vaccine boosters.

Plus, as I have discussed previously, the coronavirus almost always enters the human body via the nose and throat. Immunity in the mucosal linings of these areas tends to be relatively short lived compared to systemic immunity throughout the body. This may explain why protection against severe illness, usually rooted in the lungs, lasts longer than protection against infection.

Table of Contents

  • How common are reinfections?
  • But are reinfections milder?
  • And do reinfections strengthen immunity?

How common are reinfections?

The UK has recently started publishing data on reinfections on its COVID dashboard. It classifies a reinfection as someone receiving a new positive COVID test result more than 90 days after their last infection.

Up to February 6 2022, there had been over 14.5 million primary infections and around 620,000 reinfections in England – so one reinfection for every 24 primary infections. Over 50% of all reinfections have been reported in since December 1 2021, suggesting again that the risk of reinfection has increased substantially with omicron.

The UK’s Office for National Statistics (ONS) also measures reinfections, although does so differently. For someone to count as being reinfected, there needs to be 120 days or four consecutive negative PCR tests between the positive tests confirming their two cases. The ONS suggests that the rate of reinfection has increased 15-fold since the arrival of omicron, and that currently reinfections account for about 10% of all infections reported in England, compared to just 1% during November 2021.

A person doing a lateral flow test
Many COVID cases go undetected – so reinfections are likely undercounted.
Ink Drop/Shutterstock

However, I suspect this figure is a significant underestimate. The 90- or 120-day gap will undoubtedly miss some reinfections that occur sooner. Plus, by comparing daily recorded case numbers with estimates of how much of the population is infected with the virus at any given point in time, it appears around half of primary infections are never diagnosed. Many reinfections are therefore likely to be incorrectly categorised as primary ones. Also, if reinfections are generally milder, a higher proportion are likely to be undiagnosed.

But are reinfections milder?

Primary infections in vaccinated people (who have some COVID immunity) are generally less severe than primary infections in unvaccinated people (who don’t have any immunity) – this is why hospitalisation rates are lower among the vaccinated.

It’s reasonable therefore to assume that, in general, reinfections should be less severe than primary infections, as the person being reinfected will have some pre-existing immunity from their primary infection. Plus, many people will have been vaccinated between their infections, which will have further raised their levels of immunity.

And even though immunity against being infected by the coronavirus and developing COVID symptoms wanes, protection against severe disease and death appears much more durable. So at the extreme end of things, reinfections definitely seem to be less severe.

However, whether your second infection ends up not feeling as bad as your first may depend on when you get infected. ONS data shows the proportion of people reporting symptoms with their reinfection varies depending on what variant they were likely infected with second time round.

The ONS estimates that reinfections with alpha gave people symptoms only 20% of the time, whereas delta reinfections caused symptoms in 44% of cases and omicron in 46%. Its data also shows that people reinfected with alpha were much less likely to get symptoms the second time compared to their primary infection. Whereas delta reinfections were somewhat more likely to give people symptoms compared to their primary infection. With an omicron reinfection, the rate of symptoms was about the same across the reinfection and primary infection.

We know that the severity of COVID varies from one variant to another. However, it’s difficult to distinguish how much of the difference above is down to the different strengths of the variants, and how much is due to levels of COVID immunity from prior infection and vaccination present in people at the time.

A question that remains unanswered is whether an omicron infection in an unvaccinated person is less severe if that person has already been infected. In a small omicron outbreak in a US household, one unvaccinated person caught the virus for the first time and four unvaccinated others for the second. The illness of the person experiencing the virus for the first time was more severe the illness of those reinfected – but the very small number of cases precludes any firm conclusions.

On the other hand, there have been opposing reports in the past of more severe disease being caused by reinfection. So while it’s plausible that reinfections should be milder, at the moment, we’re still lacking robust evidence that proves this.

And do reinfections strengthen immunity?

Almost certainly yes. A single, prior infection gives similar protection against infection with omicron as two doses of vaccine, so it’s reasonable to assume that reinfections will also boost immunity.

But such immunity still won’t be 100% protective. There’s emerging evidence (in preprint) of people being reinfected multiple times. This, though, shouldn’t be surprising, as we know the other human coronaviruses cause reinfections every few years.

The Conversation

Paul Hunter consults for the World Health Organization (WHO). He receives funding from the UK National Institute for Health Research, the WHO and the European Regional Development Fund

ShareTweetSharePin
Previous Post

In research studies and in real life, placebos have a powerful healing effect on the body and mind

Next Post

I’m an addiction researcher and therapist. Here’s why promoting sober ‘dry months’ bothers me.

Next Post
I’m an addiction researcher and therapist. Here’s why promoting sober ‘dry months’ bothers me.

I'm an addiction researcher and therapist. Here's why promoting sober 'dry months' bothers me.

Most Read

What causes stuttering? A speech pathology researcher explains the science and the misconceptions around this speech disorder

What causes stuttering? A speech pathology researcher explains the science and the misconceptions around this speech disorder

December 15, 2022
morning back pain

Morning Again Ache Trigger Is Not the Mattress

October 11, 2021
lower back pain relief exercises

5 decrease again ache aid workouts

October 11, 2021
3 years after legalization, we have shockingly little information about how it changed cannabis use and health harms

3 years after legalization, we have shockingly little information about how it changed cannabis use and health harms

October 15, 2021
Nasal vaccines promise to stop the COVID-19 virus before it gets to the lungs – an immunologist explains how they work

Nasal vaccines promise to stop the COVID-19 virus before it gets to the lungs – an immunologist explains how they work

December 14, 2022
bleeding in gum

When The Bleeding in gum Is Severe ?

October 11, 2021
Good Night Sleep

6 Causes of Good Evening Sleep

October 11, 2021

COVID vaccines: how one can pace up rollout in poorer international locations

October 5, 2021
Ten small changes you can make today to prevent weight gain

Ten small changes you can make today to prevent weight gain

October 12, 2021
Support and collaboration with health-care providers can help people make health decisions

Support and collaboration with health-care providers can help people make health decisions

December 16, 2021
Greece to make COVID vaccines mandatory for over-60s, but do vaccine mandates work?

Greece to make COVID vaccines mandatory for over-60s, but do vaccine mandates work?

December 1, 2021

Multiple sclerosis: the link with earlier infection just got stronger – new study

October 12, 2021
News of war can impact your mental health — here’s how to cope

Binge-eating disorder is more common than many realise, yet it’s rarely discussed – here’s what you need to know

December 2, 2022
Nurses’ attitudes toward COVID-19 vaccination for their children are highly influenced by partisanship, a new study finds

Nurses’ attitudes toward COVID-19 vaccination for their children are highly influenced by partisanship, a new study finds

December 2, 2022
Kick up your heels – ballroom dancing offers benefits to the aging brain and could help stave off dementia

Kick up your heels – ballroom dancing offers benefits to the aging brain and could help stave off dementia

January 3, 2023
How hot is too hot for the human body? Our lab found heat + humidity gets dangerous faster than many people realize

How hot is too hot for the human body? Our lab found heat + humidity gets dangerous faster than many people realize

July 6, 2022
The promise of repairing bones and tendons with human-made materials

The promise of repairing bones and tendons with human-made materials

January 4, 2022
As viral infections skyrocket, masks are still a tried-and-true way to help keep yourself and others safe

As viral infections skyrocket, masks are still a tried-and-true way to help keep yourself and others safe

December 14, 2022
How regulatory agencies, not the courts, are imposing COVID-19 vaccine mandates

How regulatory agencies, not the courts, are imposing COVID-19 vaccine mandates

October 24, 2021
Heart disease risk from saturated fats may depend on what foods they come from – new research

Heart disease risk from saturated fats may depend on what foods they come from – new research

November 29, 2021
Late night eating may cause greater weight gain – new research points to why

Late night eating may cause greater weight gain – new research points to why

October 12, 2022

10 Things I Learned During My Body Transformation

October 12, 2021

7 Health Benefits of Sweet Potatoes

October 12, 2021
Nobel prize: how chilli peppers helped researchers uncover how humans feel pain

Nobel prize: how chilli peppers helped researchers uncover how humans feel pain

October 12, 2021
How air filters can make COVID wards safer for patients and staff

How air filters can make COVID wards safer for patients and staff

December 1, 2021
GPs don’t give useful weight-loss advice – new study

GPs don’t give useful weight-loss advice – new study

December 16, 2022
Four ways to avoid gaining weight over the festive period – but also why you shouldn’t fret about it too much

Four ways to avoid gaining weight over the festive period – but also why you shouldn’t fret about it too much

December 22, 2022
Five ways to avoid pain and injury when starting a new exercise regime

Five ways to avoid pain and injury when starting a new exercise regime

December 30, 2022
Why suicide prevention support is crucial for people with fetal alcohol spectrum disorder

Why suicide prevention support is crucial for people with fetal alcohol spectrum disorder

September 28, 2022
Too hot to handle: Climate considerations for youth sport during the hottest years on record

Too hot to handle: Climate considerations for youth sport during the hottest years on record

July 19, 2022
  • Home
  • Health & Wellness
  • Disclaimer

© 2020 DAILY HEALTH NEWS

  • Home
  • Health & Wellness
  • Disclaimer
    • Terms of Use
    • Privacy Policy
    • DMCA Notice

© 2020 DAILY HEALTH NEWS