Although the COVID-19 vaccine is highly effective in reducing morbidity and mortality, it is clear that the protection provided by current vaccines has diminished over time. This necessitates the use of safe and effective re-injections in enhancing the immune response against the virus and extending protection.

SARS-CoV-2, the virus that causes COVID-19, uses its protein to enter cells and cause infection. Every existing and upcoming vaccine relies on mimicking a mutated protein to trigger an immune response. However, each vaccine delivers the mutated protein to the immune system in different ways.

Bivalent vaccine

A divalent vaccine is a vaccine that can protect against two different viruses at the same time.

Moderna and Pfizer-BioNTech are the two main options for COVID-19 vaccinations for all age groups. An advisory committee of the Food and Drug Administration met on June 28, 2022, to evaluate the latest versions and decide which ones are likely to be recommended for use in injections. strengthen in the near future.

The divalent vaccine – which is resistant to two different viruses – Moderna combines mRNAs that encode for mutant proteins of the original SARS-CoV-2 virus as well as other mutant proteins such as the Omicron variant.

At the beginning of June 2022, Moderna said that in clinical trials, this divalent vaccine produces a stronger immune response and provides longer protection against the original SARS-CoV-2 and its variants. including omicrons.

Moderna later announced that its latest formulation also works well against the latest Omicron subvariants BA.4 and BA.5, which are rapidly becoming superior strains worldwide because of their reaction. significantly stronger immune response that the new injection induces. Moderna predicts that such protection could last a year and plans to  introduce the new vaccine in August .


On June 25, Pfizer-BioNTech also announced results for two of its new COVID-19 vaccine formulations: a divalent vaccine consisting of mRNA encoding mutant proteins of the SARS-CoV-2 strain. and a bivalent vaccine targeting only BA.1.

Whether the difference in the levels of antibodies seen in the monovalent and divalent vaccines used against the newer omicron variants remains to be established in clinical trials.

Vaccines Novavax

Another vaccine formulation in progress towards licensing is Novavax, a vaccine made using a mutant protein of the original SARS-CoV-2 virus. The Novavax vaccine has the advantage of being similar to traditional vaccines , such as DTaP vaccines against diphtheria, tetanus and pertussis, or vaccines against other viral infections such as hepatitis and shingles disease. The Novavax vaccine has been clinically tested in South Africa, the United Kingdom and the United States and has been shown to be  safe and highly effective with  90% effectiveness against COVID-19.

The Novavax vaccine is a safe and highly effective option.

In Australia, the Novavax vaccine was recently temporarily registered as a booster for individuals aged 18 years and over. The company is conducting phase 3 clinical trials to determine if its vaccine can be used as safely and effectively as the previous mRNA vaccine.

Combination of vaccines

To date, clinical studies have shown that combining existing vaccines is an effective option. For example, recent studies show that when adults have been vaccinated with the original COVID-19 vaccines (Pfizer-BioNTech, Moderna or Johnson & Johnson) the body reacts after receiving another vaccine. stronger immunity.

Mixing vaccines has been shown to be safe and effective in a variety of studies. The reason why mixing vaccines can produce a stronger immune response is that each vaccine has its own way of dealing with a different mutated protein, so when it gets into the body, there are more possibilities. to fight viruses.

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