SARS-CoV-2 continues to evolve, WHO recommends Covid-19 vaccine

According to the World Health Organization (WHO), the continued circulation of SARS-CoV-2 and the emergence of variants necessitate constant vigilance and a global mechanism for monitoring, surveillance, and assessment.

The WHO's TAG-CO-VAC (Technical Advisory Group on SARS-CoV-2 Evolution) has held meetings to assess the impact of SARS-CoV-2 evolution on the antigenic composition of Covid-19 vaccines; and to advise the WHO on whether changes to the vaccine composition are necessary.

SARS-CoV-2 tiếp tục tiến hóa, WHO khuyến cáo về vắc xin Covid-19- Ảnh 1. — Isolation and gene sequencing to assess SARS-CoV-2 mutations will help produce highly effective vaccines for disease prevention and control.

Since May, TAG-CO-VAC has recommended the use of monotherapy XBB.1 derivatives, such as XBB.1.5, as vaccine antigens. Several manufacturers (using mRNA, viral vector, and protein-based vaccine platforms) have updated their Covid-19 vaccine antigen compositions to the XBB.1.5 formulation, which has been approved by regulatory authorities for use.

Most recently, TAG-CO-VAC met again from December 4-5 to review the genetic and antigenic evolution of SARS-CoV-2, and the effectiveness of approved vaccines against circulating SARS-CoV-2 variants.

The TAG-CO-VAC's twice-yearly review of evidence is based on the need for continuous monitoring of SARS-CoV-2 evolution and the dynamics of vaccine-derived immunity.

The WHO has updated its latest information (December 13th) on the antigenic composition of Covid-19 vaccines, stating that SARS-CoV-2 continues to circulate and evolve with significant genetic and antigenic evolution of spike proteins.

The XBB.1.5 COVID-19 vaccine on different platforms produces a broad-spectrum, cross-reactive neutralizing antibody response against circulating SARS-CoV-2 variants. Given the current evolution of SARS-CoV-2 and the broad immune response demonstrated by the XBB.1.5 monotherapy vaccine against circulating variants, TAG-CO-VAC recommends retaining the antigenic component of the current COVID-19 vaccine, i.e., XBB.1.5 monotherapy, as the COVID-19 vaccine antigen.

Along with the latest information on the antigenic composition of Covid-19 vaccines, the WHO also stated that vaccination programs can continue to use any Covid-19 vaccine on the WHO's emergency use list or that has been pre-qualified.

Regarding the role of antigens in vaccine production, a vaccine and immunization expert explained that vaccines typically contain weakened or inactive parts of a specific organism (antigens). Once in the body, the vaccine triggers an immune response (producing antibodies specific to the antigen), helping the body fight off disease when infected with that pathogen.

Viruses, including SARS-CoV-2, the virus that causes Covid-19, evolve over time. When a virus replicates or makes copies of itself, it sometimes changes slightly, which is normal for viruses. These changes are called "mutations".

A virus that has one or more new mutations is called a "variant" of the original virus.

Most viral mutations have little or no effect on their ability to cause infection and disease. However, depending on the location of the changes in the virus's genetic material, they can affect the virus's properties, such as its transmissibility (for example, it may spread more or less easily); or its severity (for example, it may cause more or less severe illness).

( World Health Organization)

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