After viral infection, B cells produce protection-specific Abs such as immunoglobulin G (IgG) Abs and neutralizing Abs (NAbs) to block the virus from entering host cells and to prevent against reinfection.

Protection specific Abs

Although specific IgG Abs to SARS-CoV may have significantly waned in many recovered patients from the 2003 epidemic, and likely could not be sufficient in protecting individuals from SARS-CoV-2 infection, there is still evidence that SARS-CoV vaccines and NAbs could serve in treatment for COVID-19. For this reason, it is crucial to detect Abs titers for convalescent COVID-19 patients.

Implications of similar immune protection from SARS-CoV and SARS-CoV-2

Virus-specific neutralizing antibodies are key in creating an immune protection against viral infections. NAbs have been widely used in the past as a passive antibody therapy for SARS-CoV and Ebola virus. They are also used in evaluating the efficacy of vaccines against smallpox, polio and influenza viruses. In this study plasma samples from 175 adult COVID-19 patients admitted to Shanghai Public Health Clinical Center were collected and then screened using a sensitive pseudotyped-lentiviral-vector-based neutralization assay. All COVID-19 patients that participated in this study had mild to common symptoms and developed peak NAbs levels 10-15 days after the onset of the disease. A wide variability in NAbs plasma levels was observed among patients.

Variations of SARS-CoV-2 specific neutralizing antibodies in recovered COVID-19 patients

- PLOS ONE
- THE LANCET
- CDC
- New England Journal of Medicine (NEJM)
- Journal of Infectious Diseases
- Journal of Immunology
- JAMA Network
- MedRxiv

Antibody Immune Response for SARS-CoV References by Journal/ Source

A study showed that SARS neutralizing antibodies can successfully block SARS-CoV-2 entry into target cells in vitro, suggesting that the two viruses possess a cross-protective epitope and have similar immune protection against reinfection

Syracuse University

Northwestern University

- Vaccine Development
- Antibody immune response
- Epidemiology and transmission dynamics 

Focuses of Epidemiological studies on SARS-CoV

Infection by SARS-CoV-2 triggers the creation of antibodies in a two-part response: 
- early antibodies (IgM)
- late antibodies (IgG)

With assistance from helper T cells, B cells differentiate into plasma B cells to produce these antibodies against the SARS-CoV-2 antigens.

Antibodies and COVID-19 

Due to the varying experiences for those with COVID-19, recovery and rehabilitation look different for many individuals. As a baseline, "for persons recovered from COVID-19 illness, CDC recommends that isolation be maintained for at least 10 days after illness onset and at least 3 days (72 hours) after recovery. Illness onset is defined as the date symptoms begin. Recovery is defined as resolution of fever without the use of fever-reducing medications with progressive improvement or resolution of other symptoms. Ideally, isolation should be maintained for this full period to the extent that it is practicable under rapidly changing circumstances."

COVID-19 Recovery & Rehabilitation

Following a primary infection of SARS-CoV-2, some patients acquire a secondary infection of SARS-CoV-2, or a co-infection with a different bacteria or virus

Secondary/Co-Infections of COVID-19

Lin, Q., Zhu, L., Ni, Z., Meng, H., &amp; You, L. (2020). Duration of serum neutralizing antibodies for SARS-CoV-2: Lessons from SARS-CoV infection. Journal of Microbiology, Immunology and Infection. doi:10.1016/j.jmii.2020.03.015
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7141458/ 

Duration of serum neutralizing antibodies for SARS-CoV-2: Lessons from SARS-CoV infection

- Public Library of Science
- Nature Magazine
- Vaccine
- Cell
- New England Journal of Medicine

Vaccine Development for SARS-CoV References by Journal 

- Immunization with SARS Coronavirus Vaccines Leads to Pulmonary Immunopathology on Challenge with the SARS Virus
- Latin American Scientists Join the Coronavirus Vaccine Race

Articles on SARS-CoV Vaccine Development

SARS neutralizing antibodies and SARS-CoV-2


- Philosophical transactions of the Royal Society of London. Series B, Biological sciences
- The Lancet

Epidemiology and Transmission Dynamics of SARS-CoV References by Journal

The epidemiological study and transmission dynamics of the 2002-2003 SARS-CoV epidemic can be classified into several key areas: the viral agent, environmental factors, superspreader events, specific transmission dynamics (such as incubation and infectious periods), and the chronological progression of the outbreak's first and second waves.

Epidemiology and Transmission Dynamics of SARS-CoV

- Antibody Therapeutics
-  MedRxiv Preprint Papers
- Preprints
- Science

References for Antibodies and COVID-19 by journal

- Type I: only binds to 'up' RBD
- Type II: only binds when at least 2 RBD are 'up'
- Type III: only binds to 'down' RBD
- Type IV: recognizes both 'up' and 'down' RBD
- the image below shows the antibody interactions with RBD to the left and antibodies to the right

Types of Neutralizing Antibodies Targeting SARS-CoV-2 RBD of S protein

- NAbs targeting NTD of spike protein
- NAbs targeting S2 subunit of spike protein

Non-RBD Targeted Antibodies

Whether SARS-CoV-2 antibodies (Ab) can serve as an effective COVID-19 therapy is debated. Evidence on both sides is organized into two views: support for using SARS-CoV-2 Ab in future therapies (e.g., neutralizing antibody efficacy shown in prior coronavirus/influenza work), and evidence suggesting Ab-based therapy may not be the most viable solution (e.g., short antibody durability, antibody-dependent enhancement risk, and resistant spike mutations).

SARS-CoV-2 Antibodies as a Potential COVID-19 Therapy

COVID-19 Recovery & Rehabilitation by Continent

A study conducted on 10 COVID-19 patients undergoing recovery examined the immune cell profile using a single-cell RNA sequencing technique. In comparison to healthy controls, it found that T cells and NK cells were significantly decreased and the number of myeloid cells and monocytes with high inflammatory gene expression increased. Plasma B cells were also increased to enhance production of antibodies. 

Transcriptome Profiling of COVID-19 Patients During Recovery Stage

Specialist intervention may be necessary due to:

- Reduced physical function following ARDS, which requires regular physical examinations to restore to normal capacity

- Post-ARDS impaired cognitive function and delurium in ICU patients. 

- Depression, PTSD, anxiety, and social stigma 

Obstacles to rehabilitation may include:

- Reduced staff availability

- Lack of PPE

- Lack of capacity at rehabilitation facilities

- Co-morbidities 

- Reinfection

Virtual rehabilitation is one option for healthcare providers to use to limit physical contact but may not provide the complete benefits of rehabilitation.

Rehabilitation after critical illness in patients with COVID-19

This node categorizes references pertaining to COVID-19 recovery and rehabilitation by their publishing journal or source. Journals included in this classification are the American Journal of Physical Medicine & Rehabilitation, Cell Discovery, and the Journal of the American Medical Association (JAMA).

COVID-19 Recovery & Rehabilitation References Organized by Journal/Source

- Clinical Infectious Diseases Journal 
- European Respiratory Journal
- Journal of the American Medical Association
- Journal of Infection
- Journal of Medical Virology
- medRxiv
- The International Journal of Tuberculosis and Lung Disease
- The Brazilian Journal of Infectious Diseases
- World Health Organization

References for Secondary Infection of COVID-19 by Journal

Categories of Secondary Infections of COVID-19 

HIV patients are thought to be at increased risk of COVID-19 infection due to their compromised immune system. People living with HIV (PLWH) are especially vulnerable during the pandemic as resources and services dedicated to treatment of HIV/AIDS are limited or diverted to counter the COVID-19 pandemic.

SARS-CoV-2 and Human Immunodeficiency Virus (HIV) Co-infection

Tuberculosis (TB) is a disease caused by Mycobacterium tuberculosis and is endemic to many parts of the world. Of concern is the potential for co-infection with COVID-19 as both are spread via respiratory droplets and present with similar clinical symptoms. Due to the immunomodulatory nature of SARS-CoV-2, reactivation of latent TB infection is possible. Most diagnosis of COVID-19 may also miss TB in due to non-specific clinical features common to both diseases. TB infection may also be correlated to more severe COVID-19 disease progression, especially within endemic areas such as China and India. Active and latent TB infection can be considered to be risk factors for COVID-19. Tuberculosis should also be considered during diagnosis where patients are undergoing prolonged or unexplained clinical features.

SARS-CoV-2 and Tuberculosis (TB) Co-infection

While COVID‐19 affects countries across the world, countries in South and South‐East Asia and Latin America are faced with the prospect of a second epidemic: dengue. The countries in South America like Brazil, Paraguay, Bolivia, Argentina, Colombia, Mexico, and in the Southeast Asia like the Philippines, Malaysia, Singapore, Vietnam, Thailand, and Indonesia are currently in the high risk of dengue outbreak as dengue infection is increasing at an alarming rate. Besides, several South Asian countries like India, Pakistan, and Bangladesh are also suffering from dengue disease this year. Interestingly, almost all these countries are currently also suffering seriously from COVID‐19.

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