Tracking SARS-CoV-2 variants

All viruses, including SARS-CoV-2, the virus that causes COVID-19, change over time. Most changes have little or no effect on the characteristics of the virus. However, some changes may affect the characteristics of the virus, such as how easily it spreads, the severity of concomitant illness, the performance of vaccines, therapeutic drugs, diagnostic tools, or other public and social health measures.

WHO, in collaboration with partners, expert networks, national authorities, institutions and researchers, has been monitoring and evaluating the evolution of SARS-CoV-2 since January 2020. During late 2020, the emergence of variables that posed an increased risk to global public health prompted the characterization of specific variables of interest. (VOIs) and Variables of Concern (VOCs), in order to prioritize global monitoring and research, and ultimately to guide the ongoing response to the COVID-19 pandemic.

The World Health Organization and its international networks of experts monitor changes in the virus so that if significant substitutions for amino acids are identified, we can inform countries and the public of any changes that may be necessary to respond to the variant and prevent its spread. Globally, systems have been established and are being strengthened to detect “signals” of potential VOIs or VOCs and to assess them on the basis of risks posed by global public health. National authorities may choose to assign other variables of local interest/concern.

Reducing transmission through well-established and proven disease control methods/measures, as well as avoiding entry into animal populations, are critical aspects of the global strategy to reduce the incidence of mutations with negative public health impacts.

Current WHO-recommended strategies and measures continue to work against the viral variants identified since the start of the pandemic. Evidence from multiple countries with widespread transmission of VOCs has indicated that public health and social measures (PHSM), including infection prevention and control (IPC) measures, have been effective in reducing COVID-19 cases, hospitalizations, and deaths. National and local authorities are encouraged to continue to strengthen existing PHSM and IPC measures. Authorities are also encouraged to enhance surveillance and sequencing capabilities and apply a structured approach to provide a representative indication of transmission of SARS-CoV-2 variants based on the local context, and to detect unusual epidemiological events.

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