Researchers Reveal How Immune System Reacts to COVID Variants

Australian scientists reveal how our immune system responds to COVID-19. Antibodies produced by previous infection may not be effective against contemporary variants of the virus.

COVID-19 vaccination is more effective than the body's natural immune response after infection. New vaccine designs should be made to keep pace with emerging COVID variants, as per the the study in PLOS Medicine.

Serum of 233 patients diagnosed with COVID-19 over 7 months was analyzed and uncovered that the level of immunity over time is dependent on disease severity and the viral variant.

‘The approved COVID-19 vaccines are showing good responses. But, continued vaccine development is the need of the hour in the view of emergence of new variants.’
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Antibodies developed during the first wave show reduced effectiveness against new six variants.

The following COVID-19 strains and variants of concern/ interest were investigated:
First known classified SARS-CoV-2 strain (Wuhan -1 D614)
Alpha (B.1.1.7, United Kingdom)
Beta (B.1.351, South Africa)
Gamma (P1, Brazilian)
Zeta (P2, Brazilian)

Neutralizing antibodies help to shield cells that are usually the target of a pathogen. The level of neutralizing antibody response can be a defining feature of how effectively our body fights off illness. A rare group of 'super responders' was also identified as an exception.

COVID Vaccine Antibodies may not affect Delta Strain
Delta strain is found to be 8 times less sensitive to COVID vaccine antibodies.

Super respondents could prove useful for investigating the potential of convalescent plasma. Key donors could be looked at closely and their antibodies cloned for future therapeutic use.

"We can learn a great deal from these people who were infected in the first wave in Australia as they were infected with the same variant that our current vaccines are based on," said Associate Professor Brilot.

"While the approved vaccines are showing good responses, our study highlights the importance of continued vaccine development, especially taking into account the differences in variants."

The research was conducted to investigate the level, breadth and longevity of the immunity generated from COVID-19 infection and whether mutation of the virus compromises immunity.

"What this work has shown us is that current observations about vaccines show they offer a much broader protection against COVID-19 and its variants than the body's natural immune response following infection, which is usually only protective against the variant of the virus that the person was infected with.

We, therefore, should not rely on the body's natural immune response to control this pandemic, but rather the broadly protective vaccines that are available."

SARS-CoV-2 antibody responses remained stable in some individuals, and decreased in others, no individual showed a negative response during the seven-month period.

There were two cohorts to the study--a hospital-based cohort of patients recruited during the first and second wave of infection in Australia and a national cohort of plasma donors.

The study found that the SARS-CoV-2 antibody responses are sustained for up to seven months after infection and the response remained stable in some individuals, and while it decreased in others, no individual showed a negative response during the seven-month period.

Levels of virus-neutralizing antibodies were associated with COVID-19 severity. Antibodies generated after early infection displayed a significantly reduced antibody binding and neutralization potency to globally emerging viral variants

The longevity and type of antibody response against Spike from various variants over time in serum of COVID-19 diagnosed individuals.

Source-Medindia