Genetic Variation of COVID-19 and Vaccine Development
Dr Hossain Md Anawar
Several variants of Coronavirus have been identified from the onset of the COVID-19 outbreak. The severity of these variants is different. Some variants have intensive and deadly effects such as Delta variant, while some variants have extensive and widespread, but less deadly effects such as Omicron. The Delta variants in the beginning of the pandemic caused more death cases. However, subsequent variant, Omicron showed less deadly effects.
Different COVID-19 Variants and Their Mutations
The SARS-CoV-2 virus has changed its gene and did some mutations generating several variants that are circulating globally at the current time. The SARS-CoV-2 virus was first emerged in Wuhan, China in late 2019. After that, this virus is performing a lot of changes to it genes creating new variants. Some of these variants may have almost similar properties, while other variants may have severe impacts on human health. They may spread infection faster than other variants and have more dangerous and deadly effects (Geddes et al., 2021).
Effectiveness of COVID-19 Vaccines on Different Variants
COVID-19 vaccines will protect us from illness, deaths, social isolation, economic slowdown, educational disruptions of children, and prevent severe diseases. A good number of vaccines have been developed all over the world. Some of these vaccines are less effective against some of these variants, while the others have demonstrated satisfactory performance to reduce the number of hospitalization and deaths. Furthermore, the COVID-19 booster doses are recommended for the people for added protection against infection and severe disease.
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Production and Distribution of COVID-19 Vaccines Around the World
Vaccines can significantly fight against some diseases. But it is very difficult to affordably, reliably and successfully develop and bring a vaccine to the market in spite of significant scientific advancement. Vaccine development needs a lot of financial investments, knowledge, capacity building, time and efforts. In some cases, the anticipated results may not come in spite of great efforts. After development of vaccines, sometimes, supply shortages of existing vaccines can fail to improve human health. The vaccine development in low-resource countries faces a lot of challenges.
How Do Natural and Hybrid Immunity Work for Protection Against SARS-CoV-2?
Vaccination provides people with immunity capacity. Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) also provides natural immunity against reinfection. However, the immunity level wanes with time. Therefore, the researchers have investigated how the natural and hybrid immunity wanes with passage of time (Goldberg et al., 2022). How do natural and vaccination immunity work alone and together? How long do natural, vaccination and hybrid immunity last in human body?
Are Homologous and Heterologous COVID-19 Boosters Equally Effective Against Omicron?
A booster dose provided more protection against symptomatic Omicron infection as compared with no vaccination. The vaccine effectiveness was the highest for the cases who received a booster dose of an mRNA vaccine and was lowest who received the homologous Ad26.COV2.S/Ad26.COV2.S (Janssen) vaccine. A single booster dose of an mRNA COVID-19 vaccine after primary vaccination with a single-dose Ad26.COV2.S provided protection close to that of the three-dose mRNA vaccine regimen.
For the Ad26.COV2.S vaccine (Johnson & Johnson–Janssen) recipients, heterologous boosting was more effective than homologous boosting for protection against Omicron infection. However, there was not enough data from the general adult population, and vaccine effectiveness over time was also lacking (Accorsi et al., 2022). That’s why a booster dose of a messenger RNA (mRNA) vaccine at least 2 months after the primary dose of Ad26.COV2.S vaccine (Johnson & Johnson–Janssen) was recommended for better protection against coronavirus disease 2019 (COVID-19). The people who received Ad26.COV2.S for both the primary and booster doses, they may receive a second booster dose of an mRNA COVID-19 vaccine at least 4 months after the first Ad26.COV2.S booster dose.
A booster dose of mRNA vaccine is recommended at least 2 months after primary vaccination with single-dose Ad26.COV2.S or at least 4 months after an Ad26.COV2.S booster dose.
Suitability of mRNA-1273 (Moderna) COVID-19 Vaccine for Children Aged 6 to 11 Years
Since the onset of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), we noticed that mostly, adult people were infected by COVID-19. Therefore, the adult people were predominantly vaccinated. However, gradually children infection started to be noticed also. Therefore, the vaccination of children to prevent coronavirus disease 2019 (COVID-19) became an urgent public health issue. Creech et al. (2022) investigated the safety, immunogenicity, and efficacy of the mRNA-1273 (Moderna) vaccine in children 6 to 11 years of age.
Neutralization of the SARS-CoV-2 Deltacron and BA.3 Variants
The B.1.1.529 (Omicron) variant has undergone continuing evolution generating the emergence of the BA.1, BA.2, and BA.3 sublineages and has created serious concern over the durability of vaccine- and infection-induced immunity during the coronavirus disease 2019 (COVID-19) pandemic (Evans et al., 2022). The health concern of viral evolution through the recombination of the Omicron variant with the B.1.617.2 (Delta) variant has created serious health issues, because this new “Deltacron” variants have the ability to evade immunity induced by either vaccination or previous infection.
Necessity of New COVID-19 Vaccines in the World
There was a global shortage of COVID-19 vaccines in 2021. There will be abundant supply of vaccines by middle of 2022 to provide more equitable coverage. As of April 19, 2022, approximately 11.5 billion COVID-19 vaccine doses have been administered globally (Nohynek and Wilder-Smith, 2022). Speedy and high manufacturing capacity of the currently available vaccines by vaccine producers through the COVAX (COVID-19 Vaccines Global Access) program and beyond should secure the coverage target projected by the World Health Organization (WHO) for 70% of the world population by mid 2022.
A Sustainable Recombinant Plant-Based Adjuvanted COVID-19: How Effective and Safe?
From the beginning of out-break of COVID in 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused more than 497 million cases of coronavirus disease 2019 (COVID-19) and 6.1 million deaths globally (Hager et al., 2022). The researchers across the world have jumped into the stream of huge research and developed different types of vaccines. Most of these vaccines have the spike (S) glycoprotein as the antigen, and S-specific neutralizing antibodies have been correlated with protection against infection. The trial of these vaccines conducted in early in the pandemic generally showed high efficacy against the original Wuhan-Hu-1 strain of SARS-CoV-2 except rare, platform-related adverse events. But there had been some mutations of original virus, that generated some new variants over time such as Delta (B.1.617.2), Omicron (B.1.1.529), and Deltacron. These variants have also some sublineages. As for example, Omicron (B.1.1.529) variant has encountered further mutation creating the emergence of the BA.1, BA.2, and BA.3 sublineages. The health experts were anxious about the effectiveness and efficacy of the currently developed vaccines against the infection caused by these variants. Therefore, global research is continuing to improve the efficacy of the vaccines and also develop new vaccines.
Intramuscular AZD7442 (Tixagevimab–Cilgavimab) for Prevention of COVID-19
The development of different vaccines and their wide application have reduced and combated the severe attack of COVID-19 (Levin et al., 2022). But there are some immunocompromised people, who can’t get vaccine, are at high risk of COVID-19 infection.
Dual action single dose Moderna vaccine shot against the flu and COVID
Moderna is endeavouring to develop a single-shot vaccine for COVID-19 and the flu in near future. This product will be made at its Victorian manufacturing facility (Koehn, 2022).
End of the COVID-19 Pandemic
The number of COVID-19 cases is decreasing all over the world and the severity of the new variants is relatively lower than the earlier variants. Therefore, the people are wondering that the pandemic will end and change to localised problems or flu-like disease.