Coronavirus-2 severe acute respiratory syndrome (SARS-CoV-2), the causative agent of the current coronavirus pandemic (COVID-19), has been evolving since the first outbreak in December 2019. Researchers believe that rapid vaccination is the most effective strategy to contain the pandemic . Adam cunningham, professor of functional immunity at the University of Birmingham, says that, “Faster vaccination will ensure, a) that the vaccinated person is protected from disease and b) that the vaccinated people do not transmit the disease, therefore, those around them are also protected.“
Dr Soumya Swaminathan, Chief Scientist at the World Health Organization (WHO), declared that the main concern regarding some of the SARS-CoV-2 variants is that they have greater infectivity and can cause serious illness. She added that vaccine makers should keep a close eye on the emergence of variants and study mutation points. Accordingly, they should regularly change the structure of the vaccine.
How do new variants emerge and how do we follow them?
Mutation can occur during the viral replication process. When a virus undergoes one or more mutations, it is called a “variant” of the original virus. When a virus is transmitted rapidly within a population, the likelihood of mutations increases. Most mutations have minimal impact on the character of the virus, that is, its infectivity and symptoms. However, when mutations occur at specific genomic sites, they can alter the main properties of the virus, such as the rate of transmission and the severity of the disease.
WHO works with scientists and health officials around the world to understand the characteristics of emerging variants and their impact on both licensed COVID-19 vaccines and those in development. This is done through the global SARS-CoV-2 laboratory network which includes the Virus Evolution Working Group. This group focuses specifically on identifying new viral strains and evaluating their impact on the global population.
WHO has urged all countries around the world to thoroughly study the genomic sequence of SARS-CoV-2 and share the results in public databases. This helps researchers and health officials closely monitor, predict, and develop appropriate strategies to deal with newly emerged variants in advance. Several research groups have analyzed the genomic sequence of SARS-CoV-2 and shared it through such databases, an example being GISAID.
Evaluate the effectiveness of vaccines
WHO has set up a SARS-CoV-2 Risk monitoring and assessment framework whose main function is to identify, monitor and evaluate the variants of concern (VOCs). This team is monitoring several surveillance reports associated with COVID-19 and global VOC research. In addition, it determines the impact of VOCs on diagnostics, therapeutics and vaccines. The team is also developing appropriate guidelines for vaccine manufacturers, such as changes required in vaccine design to maintain its effectiveness against VOCs.
TO assess the effectiveness of COVID-19 vaccines, a group of researchers from Colombia Irving University Medical Center examined all spike protein mutations. They created SARS-CoV-2 pseudoviruses, which include specific mutations similar to variants, such as alpha and beta. The sensitivity of these pseudoviruses is measured using the serum of patients who have received COVID-19 vaccines.
Efficacy of Approved COVID-19 Vaccines Against SARS-CoV-2 Variants
Dr Zoltan Kis, a chemical engineer at the Future Vaccine Manufacturing Hub at Imperial College London, said: “Mutations can make existing vaccines less effective because these vaccines were developed against the ‘original’ variant of the SARS-CoV-2 virus, and the new the variants are slightly different. Kis added, “Based on the data available to date, the reduction in the effectiveness of some vaccines is around 10% for these VOCs, so they are still effective. However, he pointed out that the efficacy / efficacy values of vaccines are based on the prevention of symptomatic diseases and that the percentage values of vaccines preventing serious diseases are even higher. According to David Ho, professor of medicine at Columbia University, the virus is moving in the direction where it could escape the immune response induced by the currently available vaccine. He further claimed that if more critical mutations were to occur, researchers may need to conduct ongoing research to understand the newly developed variants of SARS-CoV-2, much like research on the influenza virus.
Ho and his colleagues analyzed blood samples from people who received Moderna or Pfizer vaccines and found that these vaccines were less effective against two variants, namely B.1.1.7 (alpha variant) and B.1.351 (beta variant) ). However, the Novavax vaccine was found to be 85.6% effective against the alpha variant.
WHO possesses reported that to date, all vaccines that have received emergency approval from various regulatory agencies around the world provide certain level of protection against new variants of SARS-CoV-2. Indeed, these vaccines are developed to trigger broad immune responses which involve the production of various antibodies and cells. In addition to antibodies, the immune system product two types of T cells, namely helper T cells and cytotoxic T cells, which can kill viruses. Helper T cells or CD4+ T cells produce antibodies and cytotoxic T cells. Cytotoxic T cells or CD8+ T cells find and kill cells infected with viruses. Studies made by the teacher Alessandro Sette and colleagues at the La Jolla Institute of Immunology in California have revealed that people who have recovered from COVID-19 produce T cells that target at least 15 to 20 different fragments of coronavirus proteins. This makes it difficult for variants to escape the immune system.
Is it possible to change the structure of the approved vaccine to increase its effectiveness against VOCs?
The researchers have declared that if an approved vaccine proves ineffective against a variant of SARS-CoV-2, its composition can be changed to provide protection. For example, a manufacturer may redesign the vaccine by incorporating more than one strain into the development phase. Kis said that in the future, if existing vaccines prove to be less effective against VOCs, manufacturers could quickly use “technology developed during this pandemic (for example, the mRNA vaccine platform) to design and to manufacture vaccines against new variants and new viruses “.
“Many vaccine developers are planning to produce new vaccines to use a booster for the initially approved vaccines, these would incorporate the cutting edge version of the newer variants. These new vaccines should both maintain the immune response to the variants covered by the original vaccine, while providing additional protection against the new variants ”, noted Professor Sarah Gilbert of the Jenner Institute at the University of Oxford.
Can vaccinated people still be infected with COVID-19?
It has been observed that even vaccinated individuals or people recovered from SARS-CoV-2 infection may still be infected with the virus. So, are the approved vaccines not effective against some of the newer variants? In this context, Gilbert noted, “No vaccine against COVID-19 currently offers 100% protection, so it is possible that a vaccinated individual could be infected. However, she added that people who are vaccinated are at risk of contracting mild illness. “The level of protection offered by a vaccine will also be different from one individual to another and will depend on a complex range of variables, including age, state of health and genetics,” she said. declared.