‘natural Immunity’ To Covid Has Its Limits
This article was originally posted in the Montreal Gazette
Quite a few people have been talking recently about natural immunity. They have heard that once you get infected with COVID-19, you have antibodies that should protect you against future infections. This is true, up to a point. But what is often neglected is that with infections, much like with vaccinations, immunity wanes with time and new variants compromise some of the protection we previously had.
Early on there was strong that people who had recovered from COVID-19 would be protected, and early evidence seemed to suggest that that would be the case. An analysis from Italy early in 2021 found that reinfections over the first year of the pandemic were rare. However, the authors themselves cautioned that their data was collected before the new variants started to circulate widely, and it was unknown how well natural immunity would hold up against new strains.
What is often lost in the discussion is the fact that infection and vaccination are not either/or propositions. An individual with a previous COVID-19 infection can and should get vaccinated. Even as early as last year before the emergence of the Omicron variant, CDC data from the United States found that people who had recovered from COVID-19 but remained unvaccinated had more than twice the odds of being reinfected compared to someone who was fully vaccinated.
Can We Catch The Omicron Variant Twice
Sadly, the answer is yes, but Professor Hunter does add some reasons for optimism.
We will be able to catch Omicron more than once, though subsequent infections will almost always be less severe than the first time round, he says. Most people who catch Omicron can probably look forward to at least a year before catching it again.
Its crucial to still show caution around Covid, though, as research is ongoing and as weve seen repeatedly, new variants can change the state of play very quickly.
If another variant comes along during that time, that could still escape immunity from Omicron and cause an earlier infection, Prof. Hunter adds.
We have no data yet about whether having a booster and catching the Omicron virus give you more protection, but it almost certainly will.
The best evidence comes from the finding that people who have had two doses and had an infection have some of the best immunity on a par with people with three vaccine doses, especially against severe disease.
This article originally appeared on HuffPost UK and has been updated.
How Protective Is Natural Immunity To Covid
Led by Susan Hopkins, the PHE SIREN study yet to be peer reviewed examined a group of healthcare workers in the UK split into a positive and negative cohort. The positive cohort consisted of 6614 people, each of whom had either a prior positive test or were antibody positive. The negative cohort containing 14,173 patients had no previous positive test for COVID-19 and tested negative for antibodies for SARS-CoV-2 .
Observing these cohorts between 18 June and 9 November 2020, SIREN found 44 reinfections in the positive cohort, compared to 402 infections in the negative cohort. Using these data, the team established that prior infection provided an 83% effective protection against reinfection .
The Rockefeller study, led by Michel Nussenzweig, examined the antibody responses of 87 people 1 and 7 months after infection. This study revealed that while antibody levels were significantly reduced at the 7month mark compared to at 1 month, the levels of memory B cells were the same, if not higher, in some individuals .
These memory B cells are produced after an initial infection and can rapidly create antibodies on reinfection with the same pathogen. Further investigation of the B cells in the participants at the 7month mark indicated that several mutations had been acquired during this time, resulting in higher quality antibodies, more capable of nullifying SARS-CoV-2 and binding to other variants of the virus .
Recommended Reading: How Much Is Rapid Testing At Cvs
How Long Does Vaccine
Some vaccine-induced immunity lasts for a long time and some does not. When it comes to the COVID-19 vaccines, theres concern about how long that protection lasts. With a rise in breakthrough infections , experts are debating whether booster doses are needed. In fact, Pfizer vaccine booster doses were for certain people in September 2021. More on this below.
Recent research suggests that the mRNA COVID-19 vaccines protection fades over time. One study that looked at Pfizers Comirnaty vaccine found that protection levels started to drop 6 months after receiving the second shot. This waning protection was more pronounced in older adults.
However, COVID-19 vaccines still effectively prevent severe cases of COVID-19 even after this 6-month window. Overall, Pfizers vaccine was found to be around 91% effective 7 days to 6 months following the second shot. Meanwhile, a recent press release from Moderna reported a vaccine efficacy of about 93%. This stayed more or less the same about 6 months following the second shot.
Because of this, only certain people are recommended to get a Comirnaty booster shot at least 6 months after receiving their second dose:
Adults at a high risk of severe COVID-19 infections
People over age 65
People who work or live in a high-risk COVID-19 environment
Memory Is Key To Long
Then come the real veterans of the immune system, which can provide long-lived and strong immunity against an infection based on their past experience.
After performing their tasks of clearing the infection or the spike protein of the virus, the antibody-producing B cells and killer T cells get converted into what are called memory cells. When these cells encounter the same protein from the virus, they recognize the threat immediately and mount a robust response that helps prevent an infection.
This explains why multiple doses of COVID-19 vaccines that increase the number ofmemory B cells prevent reinfection or breakthrough infections better when compared with a single dose. And a similar increase in memory killer T cells prevents severe disease and hospitalization.
Memory cells can remain in the immune system for long periods sometimes even up to 75 years. This explains why people develop lifelong protective immunity in certain cases, such as after measles vaccination or smallpox infection.
The trick, however, is that memory cells are highly specific. If new strains or variants of a virus emerge, as has been the case numerous times during the COVID-19 pandemic, memory cells may not be as effective.
This raises the question: When do these different key players of the immune system emerge after infection, and how long do they last?
Don’t Miss: Antigen Test At Cvs
Infection Doesnt Provide Good Immunity Against Omicron
According to a December 2021 South African study, the risk of reinfection from the Omicron coronavirus variant is 3 times higher than it is for previous strains of the virus.
The researchers analyzed 2,796,982 people who had positive test results at least 90 days before November 27, 2021. People who had sequential positive tests at least 90 days apart were considered to have suspected reinfections.
Based on their analysis, the researchers found:
- No evidence of increased reinfection risk associated with Beta or Delta variants compared to the original strain.
- Omicron variant is associated with substantial ability to evade immunity from prior infection.
in adults in the United States are from Pfizer-BioNTech, Moderna, and Johnson & Johnson.
The Centers for Disease Control and Prevention reported that vaccine effectiveness studies of people who develop COVID-19 in the real world, continue to show evidence that mRNA COVID-19 vaccines offer similar protection as they proved to in clinical trial settings.
For instance, in clinical trials, the Moderna vaccine was about 94 percent effective at preventing COVID-19 and the Pfizer-BioNTech vaccine was 95 percent effective.
Real-world data also show that Pfizer and Moderna vaccines are effective at reducing the risk of COVID-19, including severe illness, by in people who are fully vaccinated.
While the Johnson & Johnson vaccine was in clinical trials, more research is needed on how effective it is in the real world.
What Is Natural Immunity
Natural immunity is the antibody protection your body creates against a germ once youve been infected with it. Natural immunity varies according to the person and the germ. For example, people who have had the measles are not likely to get it again, but this is not the case for every disease. A mild case of an illness may not result in strong natural immunity. New studies show that natural immunity to the coronavirus weakens over time, and does so faster than immunity provided by COVID-19 vaccination.
Recommended Reading: How Much Does A Covid 19 Test Cost At Cvs
Natural Immunity Vs Vaccine
Update: A study published Feb. 3 in the Journal of the American Medical Association finds that natural antibodies from COVID-19 infection may last as long as 20 months. Experts caution, however, that these antibodies may not provide immunity from reinfection. It is yet to be determined how much natural immunity is needed to prevent infection.
Q: Whats the difference between infection-induced immunity and vaccine-induced immunity?
A: The short answer: Not much other than illness. Infection with COVID-19 or vaccination against the virus both prompt the body to produce an immune response in the form of disease-fighting antibodies and virus-targeting T-cells. These antibodies and T-cells are created in response to infection or vaccination, and ramp up if exposure to the pathogen or virus occurs.
Vaccine-induced immunity allows an individual to experience protection against severe illness from COVID-19 without first being sickened by the virus.
Infection-induced immunity may depend on the severity of illness, says Shangxin Yang, PhD, a clinical microbiologist at UCLA Health. Early studies found that people who were infected with COVID-19 but were asymptomatic or exhibited only mild symptoms mounted a less-robust antibody response.
Therefore, the efficacy of natural infection is not as predictable as vaccines, Dr. Yang says.
Q: Does immunity from natural infection last longer than immunity from the vaccine?
Get the latest updates on the COVID-19 virus and vaccines.
How Long Does It Take To Develop Covid
As mentioned above, there are two different ways your immune system can learn to make antibodies and memory cells for a virus or bacteria: natural immunity and vaccine-induced immunity.
Both are effective ways to develop immunity. However, vaccine-induced immunity allows your immune system to learn how to protect you without actually getting sick.
Theres a lot were still learning about the novel coronavirus . But heres what we know about COVID-19 immunity so far.
Also Check: How Much Does Cvs Charge For Covid Test
Does Vaccination Make A Difference To Those Who Have Already Had Covid
There is some evidence that vaccination can sharpen immunity in people who have previously been infected with SARS-CoV-2 and recovered. A letter published in the Lancet in March discussed an experiment in which 51 healthcare workers in London were given a single dose of the Pfizer vaccine. Half of the healthcare workers had previously recovered from covid-19 and it was they who experienced the greatest boost in antibodiesmore than 140-fold from peak pre-vaccine levelsagainst the viruss spike protein.14
A Focus On Earlier Strains
Cohen a senior research assistant in infectious disease prevention at the Sheba Medical Center in Ramat Gan, Israel and her colleagues recruited participants between March 25, 2020, and November 25, 2020, and completed analysis in April 2021. This means they assessed people with a history of infection from the original, the Alpha, and some Beta strains of SARS-CoV-2.
Cohen indicated that the next phase of their research will examine innate and acquired immune responses to the more recent Delta and Omicron variants.
The investigators analyzed the antibody-induced immune response up to 1 year in 130 COVID-19 recovered but unvaccinated individuals versus up to 8 months among 402 others matched by age and body mass index and without previous infection who received two doses of the Pfizer vaccine.
The numbers of antibodies a month after vaccination were higher than those in the COVID-19 recovered patients. However, these numbers also declined more steeply in the vaccinated group, they note.
To assess the antibody performance, the investigators used the avidity index. This assay measures antibody function based on the strength of the interactions between the antibody and the viral antigen.
These findings stand in stark contrast to an that found that COVID-19 vaccines provided five times the protection of natural immunity.
Don’t Miss: How Much Is Rapid Test At Cvs
Catching Covid Gives You An Immunity Boost
Coronavirus antibodies from natural infection can last for at least six months for the majority of people who have had the virus, according to a UK Biobank study of the original strain. Researchers said the results indicated antibodies produced following natural infection may provide a degree of protection for most people.
According to new analysis from the Zoe Covid Study app, 81% of participants who took an antibody test after a known Covid-19 infection tested positive for anti-N antibodies the antibodies acquired from a natural infection, not vaccination.
Professor Paul Hunter, an expert in infectious diseases at the University of East Anglia says: Infection whether with Omicron or any other variant will boost your immunity. That immunity will be better against the same variant but will also boost immunity to other variants though less powerfully. Against severe disease there is better cross immunity between variants than seen for cross immunity against mild infection.
Natural Immunity Alone Is Weak
One study compared natural immunity alone to natural immunity plus vaccination. They found that, after infection, unvaccinated people are 2.34 times likelier to get COVID-19 again, compared to fully vaccinated people. So vaccinated people have half the risk of reinfection than people relying on natural immunity alone.
“Studies show that the vaccine gives a very good booster response if you’ve had COVID-19 before,” says Dr. Rupp.
Furthermore, there is no country on the globe in which natural infection and natural immunity has brought the pandemic under control. In countries like Iran or Brazil very high levels of natural infection have not prevented recurrent waves of infection.
Don’t Miss: How Much Is Cvs Covid Testing
A Recent Study Looked At Data From Children Between 5 And 19 Years Old In Texas Usa They Evaluated The Evolution Of Antibodies Against Coronavirus Over Time What Were The Results
One of the great unknowns about COVID-19 is related to how long each person remains immune to infection, both in those who have the disease and those who have been vaccinated with one of the available formulations.
To analyze what is happening among children with this issue, a team of researchers from Texas Health Houston University, in the US, analyzed data from 218 children throughout the state of Texas.
Andthey concludedthat children previously infected with COVID-19 develop natural circulating antibodies that last at least seven months, as published in the journal Pediatrics.
For the study, experts analyzed data from children between the ages of five and 19 who enrolled in the Texas CARES survey, which had begun in October 2020, with the aim of assessing the status of antibodies to SARS-CoV-2 over time among a population of adults and children.
The volunteers provided the researchers with three separate blood draws, in samples that were collected prior to vaccination but also during waves of the Delta and Ómicron variants.
To date, researchers have completed three different phases of the study, and so far data showed that while 96% of people infected with coronavirus maintained antibodies until seven months later, more than half of the sample tested negative for infection-induced antibodies in its third and final measurement. The results do not include the impact of vaccine protection.
Johns Hopkins Research On Natural Immunity For Covid
Johns Hopkins has conducted a large study on natural immunity that shows antibody levels against COVID-19 coronavirus stay higher for a longer time in people who were infected by the virus and then were fully vaccinated with mRNA COVID-19 vaccines compared with those who only got immunized.
The data show that one month after they got their second shot, participants who had had COVID-19 more than 90 days before their first shot had adjusted antibody levels higher than those who had been exposed to the coronavirus more recently than 90 days. Three months after the second coronavirus vaccine, the antibody levels were even higher: 13% higher than those who were exposed to the virus less than or equal to the 90-day mark.
These study results suggest that natural immunity may increase the protection of the shots when there is a longer time period between having COVID-19 and getting vaccinated.
You May Like: How Much Is A Cvs Covid Test
How Long Does Natural Immunity To Covid
The more recent Rockefeller study seems to indicate that at 7 months the immunity observed was of high quality, due to the continued evolution of the B cells. To explain why these improved B cells, with their more effective antibodies, were stimulated to continue evolving after infection subsided the researchers teamed up with Saurabh Mehandru .
Testing the hypothesis that lingering viruses or sections of the virus caused this evolution, Mehandru studied intestinal biopsies from 14 individuals who had recovered from COVID-19. In seven of these individuals, Mehandru found genetic material and proteins from SARS-CoV-2 in the cells lining their intestines . The presence of these materials could well be what drove the evolution of the B cells, a theory that the team is keen to test further in more people.
Meanwhile, the SIREN study noted that the median protective effect was observed for 5 months following infection. As the study progresses, allowing for a longer follow-up time, it is quite possible that this median will increase.
Both of these studies are encouraging, suggesting that the increasingly significant number of people who have had COVID-19 are likely to be protected against reinfection for at least 5 months, potentially with increasingly effective immunity. However, these results should not be used to remake the case for the pursuit of herd immunity by allowing the unrestricted spread of the virus.
Immunity From Vaccination Versus Infection
One recent study from the U.K. Health Security Agency showed that protection against infection from two doses of vaccine may last for up to six months. Similarly, another study showed that the mRNA vaccines were highly protective at two months, but that their effectiveness decreased by seven months in part due to the emergence of the delta variant. In both studies, the vaccines were found to be better at preventing hospitalization and death than in preventing infection over time.
There are contradictory reports on whether the protective immunity triggered following an active infection is better than that induced by the current vaccines. This may have resulted from the emergence of different variants of the virus during the study.
However, the broad consensus is that COVID-19 infection can give rise to protection comparable to that from the vaccines, as shown in a recent study that has not yet been peer-reviewed.
Read Also: Cvs Covid Test Cost Without Insurance