The document summarizes current scientific evidence on immunity from natural SARS-CoV-2 infection. It finds that 90-99% of infected individuals develop detectable neutralizing antibodies within 4 weeks. Available data suggests immune responses remain robust and protective against reinfection for at least 6-8 months in most people. Some variants have reduced susceptibility to antibodies, but cellular immunity elicited by natural infection also targets other viral proteins. Studies estimate natural infection provides 80-90% protection from reinfection for up to 7 months. The emergence of variants poses challenges to immunity that require ongoing monitoring.
The first three months of the COVID-19 epidemic:
Epidemiological evidence for two separate strains of SARSCoV-2 viruses spreading and implications for prevention
strategies
Innovative Solutions to Combat Spread & Management of Covid-19Sidharth Mehta
As we know, COVID-19 is spreading worldwide and its only treatment is just Prevention from it. However there is no specific Drug/Medicine till available for this disease. In this report I try to demonstrate some Innovative Solutions to Combat Spread & Management of Covid-19. Hope you guys like this report..Please Let me know some suggestions if you have in the comment section below. #STAYHOME #STAYSAFE
Creative Biolabs has established a powerful AntInfect™ Platform for anti-virus biomolecular discovery, covering antibody and antimicrobial peptide (AMP) discovery.
https://www.creative-biolabs.com/antinfect/antibody-peptide-discovery-for-viral-disease.htm
Why is coronavirus a good biological weapon (bioweapon)?
Why is the covid-19 vaccine the ultimate endgame?
Part I of a multi-part PPT on the dangers of covid-19 vaccine.
An overview of coronaviruses. Lecture for University Biomedical Students. Using historical knowledge of coronaviruses to better understand the current SARS-CoV-2 pandemic.
The first three months of the COVID-19 epidemic:
Epidemiological evidence for two separate strains of SARSCoV-2 viruses spreading and implications for prevention
strategies
Innovative Solutions to Combat Spread & Management of Covid-19Sidharth Mehta
As we know, COVID-19 is spreading worldwide and its only treatment is just Prevention from it. However there is no specific Drug/Medicine till available for this disease. In this report I try to demonstrate some Innovative Solutions to Combat Spread & Management of Covid-19. Hope you guys like this report..Please Let me know some suggestions if you have in the comment section below. #STAYHOME #STAYSAFE
Creative Biolabs has established a powerful AntInfect™ Platform for anti-virus biomolecular discovery, covering antibody and antimicrobial peptide (AMP) discovery.
https://www.creative-biolabs.com/antinfect/antibody-peptide-discovery-for-viral-disease.htm
Why is coronavirus a good biological weapon (bioweapon)?
Why is the covid-19 vaccine the ultimate endgame?
Part I of a multi-part PPT on the dangers of covid-19 vaccine.
An overview of coronaviruses. Lecture for University Biomedical Students. Using historical knowledge of coronaviruses to better understand the current SARS-CoV-2 pandemic.
Immune Responses To The Pandemic New Coronavirus (COVID-19)by Prof. Mohamed L...Prof. Mohamed Labib Salem
In response to an invitation from Benha University, in this presentation, Prof. Mohamed Labib Salem, Prof. of Immunology, Faculty of Science, Tanta University, Egypt, presents entitled "Immune Responses To The Pandemic New Coronavirus (COVID-19)".
في هذه المحاضرة يقدم يا.د. محمد لبيب سالم أستاذ علم المناعة بكلية العلوم جامعة طنطا مصر محاضرة عن فيروس كورونا والمناعة
Before March 2020, many people saw pandemics as a thing of the past. Then came COVID-19. Scientists still do not know exactly where the virus that caused it — SARS-CoV-2 — came from, but it soon reached almost every country worldwide. Over 2 years, the virus has evolved, producing several variants. In this Special Feature, we look at the evolution of SARS-CoV-2 and ask what lessons scientists have learned.
Before March 2020, many people saw pandemics as a thing of the past. Then came COVID-19. Scientists still do not know exactly where the virus that caused it — SARS-CoV-2 — came from, but it soon reached almost every country worldwide. Over 2 years, the virus has evolved, producing several variants. In this Special Feature, we look at the evolution of SARS-CoV-2 and ask what lessons scientists have learned.
Few of the latest research findings on the novel corona virus 2019 (SARS-CoV-2) have been compiled. The basic biology of corona virus, its life cycle and its evolutionary relationship with corona viruses derived from other animals (including bats and pangolin corona viruses) has been depicted highlighting it’s inter species transmission. One of the key pathogenicity and transmissibility determinants (i.e. a furin-like S1/S2 cleavage site in the S protein) unique to SARS-CoV-2 might be responsible for its distinct mechanism to promote its entry into host cells. The last slide leaves the readers with basic research questions pertaining to the genetic divergence and evolution of coronaviruses in bats, its pathogenesis and mechanism of disease transmittance. In these times of crisis due to the outbreak of novel corona virus 2019 in Wuhan and subsequently leading to a pandemic, it is important to understand the basic biology of corona virus and the latest research findings related to its cross species transmission and key pathogenicity determinant that allows the novel corona virus a distinct mechanism to gain entry into the host cells. The structural biology approach to study the interaction of SARS-CoV-2 spike protein with receptor binding domain of angiotensin-converting enzyme-2 (ACE2) is underway and it is hoped that these findings will help in the design of new vaccines candidates targeting SARS-CoV-2 spike protein.
Right now the whole world is facing the covid-19 pandemic, and right now diagnosis and prevention of the spread of disease is the best option we have. This presentation includes methods that are currently in use for the identification of SARS-Co-V 2 / Covid-19. other than currently used methods this presentation also includes potential wearable devices that can be used for early detection of Covid-19.
SARS Corona-virus 2: Genome Sequencing And Its ApplicationSarbajitRay2
This presentation encompasses the details of genomic sequencing of SARS CoV-2 and the applications of genomic sequencing.
Prepared By:
Adyasha Nayak
Sarbajit Ray
Sugata Lahiri
Badri Prasad Sarangi
Creative Biolabs is a global leader in vaccine development. Our dedicated scientists have extensive experience in the development of new vaccines and can provide our clients with comprehensive vaccine development services to prevent infectious diseases including SARS-CoV-2.
https://sars-cov-2.creative-biolabs.com/
Research and Treatment of COVID-19 - EUCYTJensonAlbert
Current strategies to treating severely infected patients rely on repurposing therapies approved for other diseases. Additionally, there has been increased support in developing new antibodies, drugs, and vaccines which will block viral entry to cells, block viral replication, or delay the host immune system response. For more information, please visit : https://eucyt.com/
ABO Blood Groups and SARS-CoV-2 Infection by Fumiichiro Yamamoto, Ph.D.FumiichiroYamamoto
Scientific knowledge is depicted on the association between A and B glycan antigens of the ABO blood group system important in blood transfusion and cell/tissue/organ transplantation and infection of the SARS-CoV-2 virus responsible for the ongoing epidemic of coronavirus disease COVID-19.
Post vaccination -Multisystemic Inflammatory Syndrome -Adultskomalicarol
Multi-system inflammatory syndrome in adults
(MIS-A) is gaining recognition among adult physicians. MIS-A is
a rare but important syndrome that can be difficult to distinguish
from severe COVID-19. MIS- A can occur following vaccination
for SARS-CoV-2 is not reported till date.
Immune Responses To The Pandemic New Coronavirus (COVID-19)by Prof. Mohamed L...Prof. Mohamed Labib Salem
In response to an invitation from Benha University, in this presentation, Prof. Mohamed Labib Salem, Prof. of Immunology, Faculty of Science, Tanta University, Egypt, presents entitled "Immune Responses To The Pandemic New Coronavirus (COVID-19)".
في هذه المحاضرة يقدم يا.د. محمد لبيب سالم أستاذ علم المناعة بكلية العلوم جامعة طنطا مصر محاضرة عن فيروس كورونا والمناعة
Before March 2020, many people saw pandemics as a thing of the past. Then came COVID-19. Scientists still do not know exactly where the virus that caused it — SARS-CoV-2 — came from, but it soon reached almost every country worldwide. Over 2 years, the virus has evolved, producing several variants. In this Special Feature, we look at the evolution of SARS-CoV-2 and ask what lessons scientists have learned.
Before March 2020, many people saw pandemics as a thing of the past. Then came COVID-19. Scientists still do not know exactly where the virus that caused it — SARS-CoV-2 — came from, but it soon reached almost every country worldwide. Over 2 years, the virus has evolved, producing several variants. In this Special Feature, we look at the evolution of SARS-CoV-2 and ask what lessons scientists have learned.
Few of the latest research findings on the novel corona virus 2019 (SARS-CoV-2) have been compiled. The basic biology of corona virus, its life cycle and its evolutionary relationship with corona viruses derived from other animals (including bats and pangolin corona viruses) has been depicted highlighting it’s inter species transmission. One of the key pathogenicity and transmissibility determinants (i.e. a furin-like S1/S2 cleavage site in the S protein) unique to SARS-CoV-2 might be responsible for its distinct mechanism to promote its entry into host cells. The last slide leaves the readers with basic research questions pertaining to the genetic divergence and evolution of coronaviruses in bats, its pathogenesis and mechanism of disease transmittance. In these times of crisis due to the outbreak of novel corona virus 2019 in Wuhan and subsequently leading to a pandemic, it is important to understand the basic biology of corona virus and the latest research findings related to its cross species transmission and key pathogenicity determinant that allows the novel corona virus a distinct mechanism to gain entry into the host cells. The structural biology approach to study the interaction of SARS-CoV-2 spike protein with receptor binding domain of angiotensin-converting enzyme-2 (ACE2) is underway and it is hoped that these findings will help in the design of new vaccines candidates targeting SARS-CoV-2 spike protein.
Right now the whole world is facing the covid-19 pandemic, and right now diagnosis and prevention of the spread of disease is the best option we have. This presentation includes methods that are currently in use for the identification of SARS-Co-V 2 / Covid-19. other than currently used methods this presentation also includes potential wearable devices that can be used for early detection of Covid-19.
SARS Corona-virus 2: Genome Sequencing And Its ApplicationSarbajitRay2
This presentation encompasses the details of genomic sequencing of SARS CoV-2 and the applications of genomic sequencing.
Prepared By:
Adyasha Nayak
Sarbajit Ray
Sugata Lahiri
Badri Prasad Sarangi
Creative Biolabs is a global leader in vaccine development. Our dedicated scientists have extensive experience in the development of new vaccines and can provide our clients with comprehensive vaccine development services to prevent infectious diseases including SARS-CoV-2.
https://sars-cov-2.creative-biolabs.com/
Research and Treatment of COVID-19 - EUCYTJensonAlbert
Current strategies to treating severely infected patients rely on repurposing therapies approved for other diseases. Additionally, there has been increased support in developing new antibodies, drugs, and vaccines which will block viral entry to cells, block viral replication, or delay the host immune system response. For more information, please visit : https://eucyt.com/
ABO Blood Groups and SARS-CoV-2 Infection by Fumiichiro Yamamoto, Ph.D.FumiichiroYamamoto
Scientific knowledge is depicted on the association between A and B glycan antigens of the ABO blood group system important in blood transfusion and cell/tissue/organ transplantation and infection of the SARS-CoV-2 virus responsible for the ongoing epidemic of coronavirus disease COVID-19.
Post vaccination -Multisystemic Inflammatory Syndrome -Adultskomalicarol
Multi-system inflammatory syndrome in adults
(MIS-A) is gaining recognition among adult physicians. MIS-A is
a rare but important syndrome that can be difficult to distinguish
from severe COVID-19. MIS- A can occur following vaccination
for SARS-CoV-2 is not reported till date.
A brief overview of the process of vaccine production, clinical trials, and licensing, along with a summary of the different vaccines platforms and vaccine candidates.
Die britische Regierung räumt ein, dass Impfstoffe das natürliche Immunsystem von Doppelgeimpften geschädigt haben. Die britische Regierung hat zugegeben, dass Sie nach einer Doppelimpfung nie wieder eine vollständige natürliche Immunität gegen Covid-Varianten – oder möglicherweise gegen andere Viren – erlangen können. Sehen wir also zu, wie die „echte“ Pandemie jetzt beginnt! In seinem „COVID-19 Vaccine Surveillance Report“ (Woche 42) räumt das britische Gesundheitsministerium auf Seite 23 ein, dass „die N-Antikörperspiegel bei Menschen, die sich nach zwei Impfdosen infizieren, niedriger zu sein scheinen“. Es heißt weiter, dass dieser Rückgang der Antikörper im Wesentlichen dauerhaft ist. Was bedeutet das? Wir wissen, dass Impfstoffe eine Infektion oder Übertragung des Virus nicht verhindern (tatsächlich zeigt der Bericht an anderer Stelle, dass geimpfte Erwachsene jetzt viel wahrscheinlicher infiziert werden als ungeimpfte). Die Briten stellen nun fest, dass der Impfstoff die Fähigkeit des Körpers beeinträchtigt, nach einer Infektion Antikörper zu bilden, nicht nur gegen das Spike-Protein, sondern auch gegen andere Teile des Virus. Insbesondere scheinen geimpfte Personen keine Antikörper gegen das Nukleokapsid-Protein, die Hülle des Virus, zu bilden, das ein entscheidender Teil der Reaktion bei ungeimpften Personen ist. Langfristig sind die Geimpften deutlich anfälliger für eventuelle Mutationen im Spike-Protein, auch wenn sie bereits einmal oder mehrmals infiziert und geheilt wurden. Die Ungeimpften hingegen werden eine dauerhafte, wenn nicht sogar dauerhafte Immunität gegen alle Stämme des angeblichen Virus erlangen, nachdem sie auch nur einmal auf natürliche Weise damit infiziert wurden. Quelle: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1027511/Vaccine-surveillance-report-week-42.pdf Die
ICH Guidelines for Pharmacovigilance.pdfNEHA GUPTA
The "ICH Guidelines for Pharmacovigilance" PDF provides a comprehensive overview of the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines related to pharmacovigilance. These guidelines aim to ensure that drugs are safe and effective for patients by monitoring and assessing adverse effects, ensuring proper reporting systems, and improving risk management practices. The document is essential for professionals in the pharmaceutical industry, regulatory authorities, and healthcare providers, offering detailed procedures and standards for pharmacovigilance activities to enhance drug safety and protect public health.
Antibiotic Stewardship by Anushri Srivastava.pptxAnushriSrivastav
Stewardship is the act of taking good care of something.
Antimicrobial stewardship is a coordinated program that promotes the appropriate use of antimicrobials (including antibiotics), improves patient outcomes, reduces microbial resistance, and decreases the spread of infections caused by multidrug-resistant organisms.
WHO launched the Global Antimicrobial Resistance and Use Surveillance System (GLASS) in 2015 to fill knowledge gaps and inform strategies at all levels.
ACCORDING TO apic.org,
Antimicrobial stewardship is a coordinated program that promotes the appropriate use of antimicrobials (including antibiotics), improves patient outcomes, reduces microbial resistance, and decreases the spread of infections caused by multidrug-resistant organisms.
ACCORDING TO pewtrusts.org,
Antibiotic stewardship refers to efforts in doctors’ offices, hospitals, long term care facilities, and other health care settings to ensure that antibiotics are used only when necessary and appropriate
According to WHO,
Antimicrobial stewardship is a systematic approach to educate and support health care professionals to follow evidence-based guidelines for prescribing and administering antimicrobials
In 1996, John McGowan and Dale Gerding first applied the term antimicrobial stewardship, where they suggested a causal association between antimicrobial agent use and resistance. They also focused on the urgency of large-scale controlled trials of antimicrobial-use regulation employing sophisticated epidemiologic methods, molecular typing, and precise resistance mechanism analysis.
Antimicrobial Stewardship(AMS) refers to the optimal selection, dosing, and duration of antimicrobial treatment resulting in the best clinical outcome with minimal side effects to the patients and minimal impact on subsequent resistance.
According to the 2019 report, in the US, more than 2.8 million antibiotic-resistant infections occur each year, and more than 35000 people die. In addition to this, it also mentioned that 223,900 cases of Clostridoides difficile occurred in 2017, of which 12800 people died. The report did not include viruses or parasites
VISION
Being proactive
Supporting optimal animal and human health
Exploring ways to reduce overall use of antimicrobials
Using the drugs that prevent and treat disease by killing microscopic organisms in a responsible way
GOAL
to prevent the generation and spread of antimicrobial resistance (AMR). Doing so will preserve the effectiveness of these drugs in animals and humans for years to come.
being to preserve human and animal health and the effectiveness of antimicrobial medications.
to implement a multidisciplinary approach in assembling a stewardship team to include an infectious disease physician, a clinical pharmacist with infectious diseases training, infection preventionist, and a close collaboration with the staff in the clinical microbiology laboratory
to prevent antimicrobial overuse, misuse and abuse.
to minimize the developme
Medical Technology Tackles New Health Care Demand - Research Report - March 2...pchutichetpong
M Capital Group (“MCG”) predicts that with, against, despite, and even without the global pandemic, the medical technology (MedTech) industry shows signs of continuous healthy growth, driven by smaller, faster, and cheaper devices, growing demand for home-based applications, technological innovation, strategic acquisitions, investments, and SPAC listings. MCG predicts that this should reflects itself in annual growth of over 6%, well beyond 2028.
According to Chris Mouchabhani, Managing Partner at M Capital Group, “Despite all economic scenarios that one may consider, beyond overall economic shocks, medical technology should remain one of the most promising and robust sectors over the short to medium term and well beyond 2028.”
There is a movement towards home-based care for the elderly, next generation scanning and MRI devices, wearable technology, artificial intelligence incorporation, and online connectivity. Experts also see a focus on predictive, preventive, personalized, participatory, and precision medicine, with rising levels of integration of home care and technological innovation.
The average cost of treatment has been rising across the board, creating additional financial burdens to governments, healthcare providers and insurance companies. According to MCG, cost-per-inpatient-stay in the United States alone rose on average annually by over 13% between 2014 to 2021, leading MedTech to focus research efforts on optimized medical equipment at lower price points, whilst emphasizing portability and ease of use. Namely, 46% of the 1,008 medical technology companies in the 2021 MedTech Innovator (“MTI”) database are focusing on prevention, wellness, detection, or diagnosis, signaling a clear push for preventive care to also tackle costs.
In addition, there has also been a lasting impact on consumer and medical demand for home care, supported by the pandemic. Lockdowns, closure of care facilities, and healthcare systems subjected to capacity pressure, accelerated demand away from traditional inpatient care. Now, outpatient care solutions are driving industry production, with nearly 70% of recent diagnostics start-up companies producing products in areas such as ambulatory clinics, at-home care, and self-administered diagnostics.
The dimensions of healthcare quality refer to various attributes or aspects that define the standard of healthcare services. These dimensions are used to evaluate, measure, and improve the quality of care provided to patients. A comprehensive understanding of these dimensions ensures that healthcare systems can address various aspects of patient care effectively and holistically. Dimensions of Healthcare Quality and Performance of care include the following; Appropriateness, Availability, Competence, Continuity, Effectiveness, Efficiency, Efficacy, Prevention, Respect and Care, Safety as well as Timeliness.
CRISPR-Cas9, a revolutionary gene-editing tool, holds immense potential to reshape medicine, agriculture, and our understanding of life. But like any powerful tool, it comes with ethical considerations.
Unveiling CRISPR: This naturally occurring bacterial defense system (crRNA & Cas9 protein) fights viruses. Scientists repurposed it for precise gene editing (correction, deletion, insertion) by targeting specific DNA sequences.
The Promise: CRISPR offers exciting possibilities:
Gene Therapy: Correcting genetic diseases like cystic fibrosis.
Agriculture: Engineering crops resistant to pests and harsh environments.
Research: Studying gene function to unlock new knowledge.
The Peril: Ethical concerns demand attention:
Off-target Effects: Unintended DNA edits can have unforeseen consequences.
Eugenics: Misusing CRISPR for designer babies raises social and ethical questions.
Equity: High costs could limit access to this potentially life-saving technology.
The Path Forward: Responsible development is crucial:
International Collaboration: Clear guidelines are needed for research and human trials.
Public Education: Open discussions ensure informed decisions about CRISPR.
Prioritize Safety and Ethics: Safety and ethical principles must be paramount.
CRISPR offers a powerful tool for a better future, but responsible development and addressing ethical concerns are essential. By prioritizing safety, fostering open dialogue, and ensuring equitable access, we can harness CRISPR's power for the benefit of all. (2998 characters)
Explore our infographic on 'Essential Metrics for Palliative Care Management' which highlights key performance indicators crucial for enhancing the quality and efficiency of palliative care services.
This visual guide breaks down important metrics across four categories: Patient-Centered Metrics, Care Efficiency Metrics, Quality of Life Metrics, and Staff Metrics. Each section is designed to help healthcare professionals monitor and improve care delivery for patients facing serious illnesses. Understand how to implement these metrics in your palliative care practices for better outcomes and higher satisfaction levels.
Health Education on prevention of hypertensionRadhika kulvi
Hypertension is a chronic condition of concern due to its role in the causation of coronary heart diseases. Hypertension is a worldwide epidemic and important risk factor for coronary artery disease, stroke and renal diseases. Blood pressure is the force exerted by the blood against the walls of the blood vessels and is sufficient to maintain tissue perfusion during activity and rest. Hypertension is sustained elevation of BP. In adults, HTN exists when systolic blood pressure is equal to or greater than 140mmHg or diastolic BP is equal to or greater than 90mmHg. The
India Clinical Trials Market: Industry Size and Growth Trends [2030] Analyzed...Kumar Satyam
According to TechSci Research report, "India Clinical Trials Market- By Region, Competition, Forecast & Opportunities, 2030F," the India Clinical Trials Market was valued at USD 2.05 billion in 2024 and is projected to grow at a compound annual growth rate (CAGR) of 8.64% through 2030. The market is driven by a variety of factors, making India an attractive destination for pharmaceutical companies and researchers. India's vast and diverse patient population, cost-effective operational environment, and a large pool of skilled medical professionals contribute significantly to the market's growth. Additionally, increasing government support in streamlining regulations and the growing prevalence of lifestyle diseases further propel the clinical trials market.
Growing Prevalence of Lifestyle Diseases
The rising incidence of lifestyle diseases such as diabetes, cardiovascular diseases, and cancer is a major trend driving the clinical trials market in India. These conditions necessitate the development and testing of new treatment methods, creating a robust demand for clinical trials. The increasing burden of these diseases highlights the need for innovative therapies and underscores the importance of India as a key player in global clinical research.
Telehealth Psychology Building Trust with Clients.pptxThe Harvest Clinic
Telehealth psychology is a digital approach that offers psychological services and mental health care to clients remotely, using technologies like video conferencing, phone calls, text messaging, and mobile apps for communication.
Who 2019-n cov-sci-brief-natural-immunity-2021.1-eng
1. -1-
COVID-19 natural immunity
Scientific brief
10 May 2021
Key Messages:
• Within 4 weeks following infection, 90-99% of individuals infected with the SARS-CoV-2 virus develop detectable
neutralizing antibodies.
• The strength and duration of the immune responses to SARS-CoV-2 are not completely understood and currently available
data suggests that it varies by age and the severity of symptoms. Available scientific data suggests that in most people
immune responses remain robust and protective against reinfection for at least 6-8 months after infection (the longest
follow up with strong scientific evidence is currently approximately 8 months).
• Some variant SARS-CoV-2 viruses with key changes in the spike protein have a reduced susceptibility to neutralization
by antibodies in the blood. While neutralizing antibodies mainly target the spike protein, cellular immunity elicited by
natural infection also target other viral proteins, which tend to be more conserved across variants than the spike protein.
The ability of emerging virus variants (variants of interest and variants of concern) to evade immune responses is under
investigation by researchers around the world.
• There are many available serologic assays that measure the antibody response to SARS-CoV-2 infection, but at the present
time, the correlates of protection are not well understood.
Objective of the scientific brief
This scientific brief replaces the WHO Scientific Brief entitled “’Immunity passports’ in the context of COVID-19”, published 24
April 2020.1
This update is focused on what is currently understood about SARS-CoV-2 immunity from natural infection. More
information about considerations on vaccine certificates or “passports”will be covered in an update of WHO interim guidance, as
requested by the COVID-19 emergency committee.2
Methods
A rapid review on the subject was undertaken and scientific journals were regularly screened for articles on COVID-19 immunity
to ensure to include all large and robust studies available in the literature at the time of writing.
COVID-19 immune responses to natural infection
Prior exposure to SARS-CoV-2 can be assessed by detecting the presence of virus-specific antibodies in serum. Functional
neutralizing antibodies (NAb) are those able to neutralize the virus by blocking its entry into the cell.
Large cohort studies have reported that 90-99% of SARS-CoV-2 infected individuals develop neutralizing antibodies within 2-4
weeks after infection.3–7
A small proportion of individuals do not develop NAb after SARS-CoV-2 infection for reasons that are
unclear.7
Individuals with mild or asymptomatic infection tend to have lower antibody levels than those with severe disease, and
some studies have suggested that in some individuals waning of antibody levels occurs within several months after infection.6–10
Studies aimed to detect immunological memory including the assessment of cellular immunity by testing for the presence of memory
B cells, and CD4+
and CD8+
T cells, observed robust immunity at 6 months post-infection in 95% of subjects under study, which
included individuals with asymptomatic, mild, moderate and severe infections.11
2. COVID-19 natural immunity: Scientific brief
-2-
Correlates of protection against disease
How much cellular versus humoral immunity contributes to protection after natural infection is not fully understood. Studies point
at NAb as a key element of immunoprotection, with cellular immunity likely to provide additional longer-term protection especially
against severe disease and death.12–15
How long overall protection may last remains unclear, and this may differ depending on the
disease severity.7
For other human coronaviruses (hCoV), hCoV-OC43, hCoV-229E, hCoV-NL63 and hCoV-HKU-1, which cause
the common cold, antibodies last for at least a year after infection with significant inter-human variability,16
while antibodies to
more closely related MERS-CoV and SARS-CoV-1, which cause, respectively, middle east respiratory syndrome and severe acute
respiratory syndrome, can be detected for years.17–21
Reinfection
Though rarely reported to date, reinfection with SARS-CoV-2 can occur. Four large studies from the United Kingdom, the United
States of America and Denmark estimated that infection with SARS-CoV-2 provided 80-90% protection from reinfection up to 7
months, and up to 94% protection against symptomatic disease.22–25
The level of protection against re-infection as assessed by PCR
positivity was estimated to be 50% in people aged over 65 years old.24
SARS-CoV-2 variants and implications for immunity
The more the SARS-CoV-2 virus circulates, the more opportunities it has to change through natural evolution. The emergence of
virus variants can pose new challenges. Currently, three virus variants, B.1.1.7, B.1.351 and P.1, with increased transmissibility or
potential to partially escape immunity, are characterized as global Variants of Concern (VOC) by WHO and are circulating in many
countries. Evidence of reduced susceptibility to neutralization by serum antibodies of some SARS-CoV-2 variants (e.g. P.1 and
B.1.351) to natural (or vaccine-induced) neutralizing antibodies has been reported,26–29
raising the concern that reinfection after
natural infection (or breakthrough infection after vaccination) may increase in settings where these variants broadly circulate.30
Of
note, recent studies found that current global VOCs are unlikely to have an impact on CD4+
and CD8+
T cell reactivity in COVID-
19 exposed donors and vaccinees, but how this observation applies to protection against reinfection or breakthrough infection after
vaccination remains unclear.
Measuring immune responses
The immune response following infection with a virus can be measured by the detection of virus-specific antibodies such as IgA,
IgM, IgG or total antibodies through immunoassays, as well as by the detection of sensitized memory B cells and/or CD4+ and
CD8+ T cells, which require more complicated assays. The most commonly measured immune response is the presence of antibodies
in serum. Serologic assays to detect the antibody response are usually based on enzyme immunoassays, which detect the presence
of virus-specific antibodies in the blood or by live or pseudo-virus neutralization assays, which detect functional NAb. While
serologic testing has limited use in clinical management because it does not capture active infection, it can be very useful in
determining the extent of infection or estimating attack rates in given populations.
Interpreting the results of serologic testing, however, is complex: there are several antibody types and subtypes and multiple
antigenic determinants/epitopes that can be used to target these antibodies, and the results may differ substantially depending on the
combinations chosen. The results will also depend on the manufacturing specifics of the assay used. The most frequently used assays
for detection of antibodies to SARS-CoV-2 are enzyme-linked immunosorbent tests, chemiluminescent tests, and lateral flow rapid
diagnostic tests (RDTs). Advice on the use of RDTs for antibody detection is available on the WHO website.32
Conclusions
Current evidence points to most individuals developing strong protective immune responses following natural infection with SARS-
CoV-2. However, inaccurate immunodiagnostic tests may falsely indicate infected individuals as naïve to the virus (not previously
infected) or may falsely label non-infected people as positive for immune markers of recent infection.
To conclude, available tests and current knowledge do not tell us about the duration of immunity and protection against reinfection,
but recent evidence suggests that natural infection may provide similar protection against symptomatic disease as vaccination, at
least for the available follow up period.33
The emergence of variants of concern poses challenges and their potential to evade
immunity elicited by either natural infection or by vaccination, needs to be closely monitored.
3. COVID-19 natural immunity: Scientific brief
-3-
Plans for updating
WHO continues to monitor the situation closely for any changes that may affect the information in this Scientific brief. Should any
factors change, WHO will issue a further update. Otherwise, the validity of this brief will be reviewed 3 months after the date of
publication.
Contributors
Lorenzo Subissi, Mick Mulders, Martin Friede, Maria Van Kerkhove, Mark Perkins.
Acknowledgments
We thank Stanley Perlman for critical reading of this scientific brief.
References
1. World Health Organization. “Immunity passports” in the context of COVID-19. Available from: https://www.who.int/news-
room/commentaries/detail/immunity-passports-in-the-context-of-covid-19
2. World Health Organization. Statement on the seventh meeting of the International Health Regulations (2005) Emergency
Committee regarding the coronavirus disease (COVID-19) pandemic. Available from: https://www.who.int/news/item/19-
04-2021-statement-on-the-seventh-meeting-of-the-international-health-regulations-(2005)-emergency-committee-regarding-
the-coronavirus-disease-(covid-19)-pandemic
3. Wajnberg A, Mansour M, Leven E, et al. Humoral response and PCR positivity in patients with COVID-19 in the New York
City region, USA: an observational study. Lancet Microbe [Internet] 2020 [cited 2021 Mar 26];1(7):e283–9. Available from:
https://linkinghub.elsevier.com/retrieve/pii/S2666524720301208
4. Guthmiller JJ, Stovicek O, Wang J, et al. SARS-CoV-2 Infection Severity Is Linked to Superior Humoral Immunity against
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