This question is arising as those patients with asymptomatic, mild or moderate COVID-19 are recovering. Is the degree of immunity dependent on:
1. Severity of the disease
2. IgG titer in the recovered patients
These question becomes more relevant because until a vaccine for the 2019-nCoV is available, convalescent patient sera can be used to improve the immunity in early stage of COVID-19, as was used with success in the treatment of several Ebola patients during the outbreak in 2014–2015.
Dear colleague have a nice day. In this RG question there are some attempt to search the causes of the incredible (humanitarian) case of mortality rate in N. Italy (Lombardia & Emilia Romagna). https://www.researchgate.net/post/The_novel_Coronavirus_in_N_Italy_Lombardia_COVID19_2019nCoV_SARSCoV2_shows_a_fatality_rate_compatible_with_SARS_Why ...... These data https://www.researchgate.net/publication/339781431 .. are very similar to SARS or MERS.
As SARS-CoV-2 is a rather novel pathogen there are so far no studies and insights on the persistence of immunity after recovery from COVID-19.
Thanks to all who responded. I agree that being a novel virus, and in the absence of any such study nobody can speculate let alone predict scientifically answer the duration of immunity.
One answer (from Ajith Kumar) to the question of IgG/IgM antibody test was:
Saw a product listing from Kurabo for SARS-CoV-2 Antibody IgM/IgG Testing
https://www.kurabo.co.jp/bio/English/product/products.php?M=D&PID=111
There is no study so far, but for people with mild symptoms and/or full recovery this could be a tool to find out more about their immunity?
The duration of immunity after recovery from coronavirus disease (COVID-19) is not yet known.
Its not clear yet, because this virus is new pathogen and there is no enough informations about it.
There is also no reliable IgM/IgG test system so far. Several rapid tests (RDT) have been developed, but theses sysmtems are still poorly evaluated.
Reports indicate that aperson infected with COVID 19 has a immunity for a short period and can be infected for the second time .
https://www.kurabo.co.jp/bio/English/product/products.php?M=D&PID=111
Updates: Now a recent study shows that starting with second week of the COVID-19 illness, most of the patients develop antibodies, IgM followed by IgG. By one month almost all of the patient have antibodies against SARS-CoV-2 (1).
The sera of convalescent patients who recovered from COVID-19 have already shown encouraging results in recovery from COVID-19 (2).
However, there is still no data about the duration of immunity after recovery from COVID-19.
1. https://watermark.silverchair.com/ciaa344.pdf?
2. Article Treatment of 5 Critically Ill Patients with COVID-19 with Co...
"Someone with a normal immune system that can react to the virus and get better should have immunity for quite some time, at LEAST A YEAR, if not lifelong."
This was a reply by US expert (Dr. Buchholz) in a Q & A session with The Guardian Newspaper:
Dr David Buchholz, senior founding medical director, primary care, assistant professor of pediatrics, Columbia University Irving medical center, United states.
Read this link:
https://www.google.com/search?q=Have+I+already+had+coronavirus%3F+How+would+I+know+and+what+should+I+do%3F&oq=Have+I+already+had+coronavirus%3F+How+would+I+know+and+what+should+I+do%3F&aqs=chrome..69i57j69i60.2190j0j7&sourceid=chrome&ie=UTF-8
However, to date there is no published study on the duration of immunity after COVID-19.
Further updates
The reports of re-infection after recovery from COVID-19 in the literature (1) most likely represent laboratory error resulting from the sensitivity of the kits used.
In the a study (2) patients declared positive after recovery were still positive by amore sensitive test. Reassuringly, all the patients had a good immune response based on SARS-CoV-19 specific antibody tests.
1. Article Positive RT-PCR Test Results in Patients Recovered from COVID-19
2. Preprint Clinical characteristics of the recovered COVID-19 patients ...
In South Korea, reinfection occurred in 91 cured patients and led again to COVID-19 symptoms
Convalescent Rhesus macaque monkeys after infection with SARS-CoV-2 develop immunity to re-infection, however, protective effect of antibodies in Humans is not known.
An animal study on rhesus macaque monkeys after experimental infection with SARS-CoV-2 showed that they were protected to reinfection by producing disease-specific antibodies in the convalescent period (1). However, the duration of the protective effect was not studied further. It is unlikely that ethically such a study would be done in Humans (2).
Although, production of antibodies have been described in convalescent period in humans who recovered from COVID-19 infection (3-4), whether such antibodies are protective is unknown.
Also we don't know the duration of such protection unless we wait and follow up convalescent patients long enough (1 year minimum) as we are still less than FOUR months into current COVID-19 pandemic.
1. Preprint Reinfection could not occur in SARS-CoV-2 infected rhesus macaques
2. https://www.fhi.no/globalassets/dokumenterfiler/rapporter/2020/immunity-after-sars-cov-2-infection-report-2020.pdf
3. https://www.medrxiv.org/content/10.1101/2020.03.20.20039495v1
4. Article Profile of specific antibodies to SARS-CoV-2: The first report
5. Article Detection of serum immunoglobulin M and immunoglobulin G ant...
@ Christian G Meyer
The reports of recurrence of COVID-19 are proven to be related to quality issues of the kits used for testing as shown in the study below.
Furthermore, clinically none of such patients have been shown to infect contacts in the family and had no further symptoms or signs of active infection.
Preprint Clinical characteristics of the recovered COVID-19 patients ...
90% of the patients may have undocumented (possibly asymptomatic) COVID-19 infection.
Now mass testing of people in Germany and New York, USA has started.
Initial results of antibody tests in New York indicate that compared to documented positive COVID-19 patients, the number of patients exposed to the virus are 10 times more. This indicates that undocumented patients are 1o times the documented patients.
https://www.ny1.com/nyc/all-boroughs/news/2020/04/23/governor-cuomo-daily-coronavirus-update-with-first-antibody-test-results
Duration of immunity after recovery from COVID-19 yet to be determined.
More questions than answers about immunity after recovery from COVID-19.
Latest from JAMA:
Article COVID-19 and Postinfection Immunity: Limited Evidence, Many ...
Recently Singapore stopped using RNA-based PCR tests to release COVID-19 patients from isolation because RNA tests in a clinically recovered patients are useless.
https://english.nna.jp/articles/15151
The antibodies developing after recovery from COVID-19 are short lived just like coronaviruses causing common cold. So no meaningful immunity.
The results of this article is shattering the world:
https://www.medrxiv.org/content/10.1101/2020.06.13.20130252v1.full.pdf
The duration of immune development after recuperation from (COVID-19) is not yet known, although, the plasma collected from covid-19 recovered patient are using as a treatment in our country after 90 days in some cases.
Dear Mohammad Arman,
In the studies available to date in COVID-19 recovered patients, the maximum duration for which the antibodies against SARS-CoV-2 have been tested have been 8 weeks after recovery (1-2). Important issue is that, the the antibody titer is not uniform in all such patients. Therefore, indiscriminately transfusing plasma from convalescent patients is not recommended (3).
1. Preprint Prevalence of IgG antibodies to SARS-CoV-2 in Wuhan - implic...
2. Preprint Evaluation of antibody testing for SARS-Cov-2 using ELISA an...
3. Preprint Serological Analysis of New York City COVID19 Convalescent P...
The duration of immunity after recovering from COVID-19 is at least 8 months.
https://immunology.sciencemag.org/content/5/54/eabf8891
Preprint Human coronavirus reinfection dynamics: lessons for SARS-CoV-2
Thanks Arvind Singh, Mahammad Khuddush, and Dhifaf Zaki.
Although this question about immunity after COVID-19 was one of the earliest such questions (March 2020), it is only recently that knowledge about immunity against SARS-CoV-2 is becoming more clear.
A latest study in NEJM in health care workers has also shown that the immunity after SARS-CoV-2 infection lasts at least SIX months.
Antibody Status and Incidence of SARS-CoV-2 Infection in Health Care Workers
https://www.nejm.org/doi/full/10.1056/NEJMoa2034545
According to NIH, the immune systems of more than 95% of people who recovered from COVID-19 had durable memories of the virus up to eight months after infection. The results provide hope that people receiving SARS-CoV-2 vaccines will develop similar lasting immune memories after vaccination
These two articles indicate that the immunity after recovery from COVID-19 may be longer than 6 or 8 months, simply because the people in the study have not been followed up for a longer time.
Immunity in fact may be longer and would be unveiled by further and longer follow up of cohorts of patients who recovered from COVID-19.
1. Preprint Robust SARS-CoV-2-specific T-cell immunity is maintained at ...
2. Article Immunological memory to SARS-CoV-2 assessed for up to 8 mont...
From weeks to months. But it depends on the individual
Implications of SIREN study in health care workers
According to this study done in the UK in Health Care Workers (HCWs), the cohort having evidence of previous documented SARS-CoV-2 infection had the following observations:
1. The immunity was noted up to 7 months after the incident COVID-19 infection
2. 155 infections were detected in the baseline positive cohort of 8278 participants (1.87%).
3. The cohort with past COVID-19 after reinfection were mainly asymptomatic or had milder symptoms with no mortality.
This augurs well regarding immunity after most people who have recovered from COVID-19. Immunity may last for over 7 months (more follow up of this cohort will be more informative for assessment of long-term immunity. However, most of such HCWs were female and younger. The immunity duration after SARS-CoV-2 infection will need more such studies in people >65 years particularly in males who are mainly being affected by COVID-19 pandemic.
https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)00675-9/fulltext
Immunity after even a mild COVID-19 infection lasts longer the 12 months
According to a study in Nature journals (1), immunity even a mild COVID-19 infection lasts well over 12 months and it may get further boost by a COVID-19 vaccine.
Article Vaccination boosts naturally enhanced neutralizing breadth t...
If despite the scientific evidence someone is uncertain about COVID-19 and its vaccination, then this is height of skepticism.
It is rife all over the world, particularly educated, and well informed communities, and even the scientists as you can see in these links:
1. https://www.nytimes.com/2021/04/29/us/vaccine-skepticism-beliefs.html
2. https://apnews.com/article/ap-norc-poll-3rd-adult-skeptical-vaccine-3779574a6d45d38cfc1d8615eb176b2d
3. https://www.reuters.com/investigates/special-report/health-coronavirus-vaccines-skeptic/
How Long Does Immunity Last After COVID-19? What We Know
https://www.healthline.com/health-news/how-long-does-immunity-last-after-covid-19-what-we-know
Dear Chuck A Arize
Thanks for your input.
The natural immunity after COVID-19 has been anywhere between 6-12 months as reported in different studies.
Immunity after mild COVID-19 is different in children compared to adults
According to the JAMA study linked below, immunity as gauged by the antibody production and titer was less in children compared with adults
Article Comparison of Seroconversion in Children and Adults with Mild COVID-19