A review of natural immunity as well as vaccines and variants in SARS-CoV-2 reinfection

The coronavirus disease 2019 (COVID-19) pandemic is an ongoing global health issue caused by the novel coronavirus severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2).

To understand the underlying causes of SARS-CoV-2 as well as its transmission numerous rigorous studies have been done. Despite all these efforts there are many areas that remain not explored, such as SARS-CoV-2 reinfection as well as reactivation.

To assess the possibility of reinfection, and to determine the risk factors, more thorough research is required.

Literature review on COVID-19 reinfection

In a review of the literature published in the Journal of Community Hospital Internal Medicine Perspectives the authors from the US performed a thorough investigation of previous studies and reports of cases of SARS-CoV-2 re-infection. This review examines the role of natural immunity, vaccines and variants of SARS-CoV-2 in reinfection.

Study COVID-19: the importance of natural immunity, vaccines and variants. Image Credit: NIAID

Definition of reinfection

The Centers for Disease Control (CDC) defines reinfection as “an infection in a person who has two different strains of virus within >=45 day in cases of COVID-19 that are highly suspicious, or >=90 day in asymptomatic or low suspicion cases.”

In addition, some studies define reinfection as having negative tests in between two positive SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) tests besides the genotypic variation.

This review examined reinfection in individuals who were tested positive for SARS-CoV-2 by RT-PCR. It also monitored the study group from September 2020 until December 2020 to assess SARS-CoV-2 contraction.

A study by Tillett et al. The first case of reinfection in the US was discussed by Tillett et . al.

Another study by Hall et al. discovered that the prior SARS-CoV-2 history can lower the risk of reinfection by 83%. Its protective effect could last for up to 5 months.

Many studies have been published about the properties and durations of immunity , which play an a significant role in the process of reinfection.

Specific antigens against coronavirus sars-cov-2. Image Credit: Corona Borealis Studio

SARS-CoV-2 post-acute sequelae

COVID-19 patients experience numerous signs of inflammation and immune dysregulation within 4 weeks after the onset of the infection. These are known as post-acute sequelae (PASC) and are always considered to be reinfection. Understanding the distinction between PASC reinfection and infection is essential to manage COVID-19.

Infection prevention and vaccination

The US Food and Drug Administration (USFDA), has approved vaccines that target the spike glycoprotein in SARS-CoV-2. A two-dose vaccine regimen with Moderna/National Institute of Allergy and Infectious Diseases is around 95 percent effective in preventing symptoms of COVID-19. A single dose Johnson and Johnson Janssen Biotech vaccine regimen is 65.5 percent effective.

Other vaccines, including AstraZeneca/Oxford Covaxin, and Sputnik V vaccines have the ability to work 78%, 70.4% and 91.6% respectively, and have been approved elsewhere in the world. However, certain vaccines developed in China and other countries are in different phases of clinical trials.

New variants of concern include SARS-CoV-2 B.1.1.7, B.1.351, Beta, B.1.617.2, and Delta. (Gamma), B.1.427 and B.1.429 (Epsilon) and finally B.1.1.529 (Nu) (Nu) have been discovered, all of which carry mutations in the receptor-binding region of the spike protein. This is why the emergence of different variants of SARS-CoV-2 leads to uncertainty regarding the effectiveness of vaccines.

Antibodies and reinfection

The majority of patients with COVID-19 have IgG and IgM levels that rise shortly after symptoms onset. Many patients with COVID-19 don’t develop antibodies. This may be due to unidentified reasons. Patients suffering from severe COVID-19 are more likely to have antibodies than patients with milder or less severe infections. Within 60-90 days after the onset of infection the antibody levels begin to decrease. There are reports that suggest that these antibodies can cause immune system that lasts for up to 12 months. A study by To et al. To et al. discovered that the possibility of reinfection can be determined if there is an increase in the immune response to IgG neutralizing antibody and a lack of IgM antibodies.


The study concluded that antibodies are the reason for SARS-CoV-2 immunity as well as the longevity of reinfection. It is beneficial to examine the role of vaccines in reinfections that involve different strains in order to better comprehend the notion of reinfection. The authors suggest more comprehensive research on patients’ viral loads, viral genotypes as well as antibodies and immune status to confirm true reinfection. Patients with asymptomatic infections must be assessed for the possibility reinfection or reactivation.

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Content Source:

Gemma Wilson

Gemma is a journalism graduate with keen interest in covering business news – specifically startups. She has as a keen eye for technologies and has predicted quite a few successful startups over the last couple of years.

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