The WHO chief has recommended several measures to check the emergence of new COVID-19 variants. These measures include: 1. Continuing COVID-19 testing: Ongoing testing is essential to detect any new virus variants in circulation. This allows for timely identification and monitoring of changes in the virus. 2. Sequencing and analysis: Genomic sequencing of the virus samples helps identify new variants and understand their characteristics. It enables researchers to study their potential impact on transmission, severity, and response to treatment or vaccines. 3. Collaboration and data sharing: International collaboration and sharing of data among countries are crucial in tracking and understanding the emergence and spread of new variants. This helps in implementing appropriate measures in a coordinated manner. 4. Surveillance: Strengthening disease surveillance systems helps in early detection and monitoring of new variants. Regular analysis of epidemiological data and patterns can identify emerging hotspots and potential sources of new variants. 5. Vaccine effectiveness monitoring: Continuous monitoring of vaccine effectiveness against emerging variants provides valuable information for adapting vaccination strategies and optimizing vaccine development. Implementing these measures will help in closely monitoring and responding to the emergence of new COVID-19 variants, thereby aiding in effective control and management of the pandemic.